Seeking information on SATA hard drive hot-swapping . . .

[Stan Shankman]

Greetings all,



I have been reading around the internet, and trying to learn a few things
regarding SATA and hot-swapping.



This is what I want to do:



I want to permanently mount one SATA drive in my computer (to be used as the
boot and system drive). And then also, I want to use one of those fancy
drive sleds to plug and unplug additional SATA drives (for data and backup
use).



I would like to simply reach over and yank out the removable drive any time
I wish, and replace it with another drive. (Now, if I have to go to the
system tray, and tap on dismount or something like that, so be it - I just
want to know what I must do.)



Now, in researching this, I come up will all manner of contradictory
information - some people saying it can't be done without special software
etc. etc. etc.



But I am pretty sure that it can be done. I think the use of a controller
that a supports SATA hot-swapping is mandatory. Yet I do not have a good
understanding of this controller issue. - I wonder, could any SATA
controller support hot-swapping if it had a proper driver? Or is there some
hardware issue involved? I don't know. One thing I have discovered is that
controllers are not well marketed insofar as hot-swapabilty is concerned. It
is not clear whether a SATA controller specification that claims "support
for hot-swapping" is referring to just a RAID or not. - By the way, I do not
wish to run a RAID. I do not yet know if a controller that supports
hot-swapped RAIDs is by implication also able to support single dive
hot-swapping. Is there a distinction? I don't know.



Oh, and you think that is bad? What about the motherboard based SATA
controllers. Just try to find out if yours supports SATA hot-swapping or
not. It's like pulling teeth trying to find out this information.



Do all SATA drive sleds work with SATA II? If not, why not? What, for that
matter, does a drive sled do? Why is it not just a convenient place to house
a couple of connectors? Or is, in fact, that all there is to it? I mean, is
it possible to not use a drive sled at all? Can one simply make the SATA
cable and power cable accessible and then manually plug and un-plug SATA
drives? I mean isn't that what the SATA hot-swap specification calls for? If
not, what is the true definition of hot-plugging?



Anyway, I want to hear from guys that are involved with the same thing. If
you are hot-swapping SATA drives, please reply and let us (me and the Usenet
community) know your story. What can you tell us about your experience? What
do we need to know?



Oh, and for the record, I am talking about Windows XP Pro.



Thanks all,



- Stan Shankman

 

[Peter]

So you want to be able to pull one SATA drive and push another one under
live Windows XP?
Without any RAID? Without going to "safely remove hardware" or similar
manual procedure?
Without risking of data corruption? You must be dreaming.

 

[Anna]

Greetings all,

I have been reading around the internet, and trying to learn a few things
regarding SATA and hot-swapping.

This is what I want to do:

I want to permanently mount one SATA drive in my computer (to be used as
the
boot and system drive). And then also, I want to use one of those fancy
drive sleds to plug and unplug additional SATA drives (for data and backup
use).

I would like to simply reach over and yank out the removable drive any
time
I wish, and replace it with another drive. (Now, if I have to go to the
system tray, and tap on dismount or something like that, so be it - I
just
want to know what I must do.)

Now, in researching this, I come up will all manner of contradictory
information - some people saying it can't be done without special software
etc. etc. etc.

But I am pretty sure that it can be done. I think the use of a controller
that a supports SATA hot-swapping is mandatory. Yet I do not have a good
understanding of this controller issue. - I wonder, could any SATA
controller support hot-swapping if it had a proper driver? Or is there
some
hardware issue involved? I don't know. One thing I have discovered is that
controllers are not well marketed insofar as hot-swapabilty is concerned.
It
is not clear whether a SATA controller specification that claims "support
for hot-swapping" is referring to just a RAID or not. - By the way, I do
not
wish to run a RAID. I do not yet know if a controller that supports
hot-swapped RAIDs is by implication also able to support single dive
hot-swapping. Is there a distinction? I don't know.

Oh, and you think that is bad? What about the motherboard based SATA
controllers. Just try to find out if yours supports SATA hot-swapping or
not. It's like pulling teeth trying to find out this information.

Do all SATA drive sleds work with SATA II? If not, why not? What, for that
matter, does a drive sled do? Why is it not just a convenient place to
house
a couple of connectors? Or is, in fact, that all there is to it? I mean,
is
it possible to not use a drive sled at all? Can one simply make the SATA
cable and power cable accessible and then manually plug and un-plug SATA
drives? I mean isn't that what the SATA hot-swap specification calls for?
If
not, what is the true definition of hot-plugging?

Anyway, I want to hear from guys that are involved with the same thing. If
you are hot-swapping SATA drives, please reply and let us (me and the
Usenet
community) know your story. What can you tell us about your experience?
What
do we need to know?

Oh, and for the record, I am talking about Windows XP Pro.
Thanks all,
- Stan Shankman

I assume your reference to "drive sleds" refers to mobile racks designed to
house removable hard drives.

Here's some general background information we've picked up over the past
year or so concerning "hot swapping" SATA hard drives...

Based on our contacts with the SATA-IO organization
(http://www.sata-io.org), the lead organization developing specifications
for the SATA-IO HDs, (the "IO" denoting "International Organization"),
formerly called SATA-II (and apparently still known by that latter
designation by most users), and a number of HD manufacturers, here's what
we've been able to glean re this "hot-plugging" issue as it applies to SATA
HDs...

There are two basic requirements for SATA hard drives to be "hot-pluggable"
(a/k/a "hot-swappable"), to wit...
1. The SATA HD must have this capability. The manufacturer must
*specifically* indicate that the particular drive is hot-pluggable capable.
BTW, both the earlier SATA HDs having a data transfer rate of 1.5 Gb/s and
the latest SATA-IO HDs having a data transfer rate of 3 Gb/s can be
hot-pluggable. According to the information we received from the SATA-IO
organization, the user cannot assume that merely because the drive is
designated SATA-IO (SATA-II) it is inherently hot-pluggable. It would seem
that in theory this *should* be so presuming the drive meets SATA-IO
specifications, but we were cautioned not to make this assumption and as
indicated, contact the drive's manufacturer for verification.

2. The motherboard must support hot-plugging capability, i.e., its SATA
controller must provide hot-plugging support.

One other consideration...
SATA native hot plug as defined by the specification requires the use of the
15-pin SATA power connector, *not* the 4-pin Molex power plug commonly used
to connect IDE devices and frequently found on SATA HDs alongside the SATA
power connector. Furthermore, the specification also calls for a requirement
that the power signal cables be connected/disconnected *simultaneously* in
order for native SATA hot plugging to be supported. (In our case, we
accomplish this by mounting the external SATA HDs in the removable
tray/caddy in mobile racks so a simple push or pull on the removable tray's
handle simultaneously connects/disconnects both the power/signal cables.)

I have to admit that every SATA-IO HD we've worked with for nearly a year
now (WD, Hitachi, Samsung, and Seagate, all SATA-IO drives) has proven to be
hot-pluggable. I would add that in many instances while experimenting with
the hot-plugging capability of the afore-mentioned SATA drives while they
were connected as external devices, we've connected/disconnected the drives
without regard to any simultaneous connection or disconnection of the data &
power connectors and we suffered no ill effects that we're aware of in terms
of data loss/corruption or damage to the drives. At least none to date. Even
in cases where the SATA HD received its power through the Molex plug we
didn't run into any problems, but we really did not do extensive testing
with that configuration. In nearly every case power was applied to the SATA
HD though its 15-pin power connector.
Anna

 

[Rod Speed]

I have been reading around the internet, and trying to learn a few
things regarding SATA and hot-swapping.

This is what I want to do:

I want to permanently mount one SATA drive in my computer
(to be used as the boot and system drive). And then also,
I want to use one of those fancy drive sleds to plug and
unplug additional SATA drives (for data and backup use).

I would like to simply reach over and yank out the removable
drive any time I wish, and replace it with another drive.

That isnt a great idea, most obviously if
the system is currently writing to the drive.

(Now, if I have to go to the system tray, and tap on dismount or
something like that, so be it - I just want to know what I must do.)

Presumably you would also be happy to check that the drive
isnt currently being used before you physically remove it, say
with some sort of activity light etc.

Now, in researching this, I come up will all manner
of contradictory information - some people saying it
can't be done without special software etc. etc. etc.

Yes, its quite a mess currently.

But I am pretty sure that it can be done.

Yes it can.

I think the use of a controller that a supports
SATA hot-swapping is mandatory.
Correct.

Yet I do not have a good understanding of this
controller issue. - I wonder, could any SATA
controller support hot-swapping if it had a proper
driver? Or is there some hardware issue involved?

That isnt completely clear currently.

I don't know. One thing I have discovered is that controllers
are not well marketed insofar as hot-swapabilty is concerned.

Yeah, but thats also true of the basic question
about whether it supports non RAID configs too.

It is not clear whether a SATA controller specification
that claims "support for hot-swapping" is referring to
just a RAID or not.
Yep.

By the way, I do not wish to run a RAID. I do not yet know if a
controller that supports hot-swapped RAIDs is by implication also
able to support single dive hot-swapping. Is there a distinction?
Yes.

I don't know.

Oh, and you think that is bad? What about the motherboard based SATA
controllers. Just try to find out if yours supports SATA hot-swapping
or not. It's like pulling teeth trying to find out this information.

True of whether its designed to support non RAID too,
although thats becoming less true than it used to be.

Do all SATA drive sleds work with SATA II?
Nope.

If not, why not?

Some of them are very poor designs which dont even
fully support SATA, essentially because they flout the
SATA standard in some areas, essentially because
they appear to be crude kludges of ATA drive 'sleds'

Then there's the separate question of the power connector.

Quite a few drives have a molex connector, the old ATA
power connector, and that cannot be used for hot swapping.

What, for that matter, does a drive sled do?

Its mostly about the mechanical stuff, providing a decent
solid way of sliding the drive in and out of the system.

Why is it not just a convenient place
to house a couple of connectors?

Because there is more involved than just the connectors.

The mechanical arrangement needs to be convenient,
and many have some form of fan etc because those
configs dont get much airflow over the drive.

Or is, in fact, that all there is to it?
Nope.

I mean, is it possible to not use a drive sled at all? Can one
simply make the SATA cable and power cable accessible
and then manually plug and un-plug SATA drives?

Nope, because the standard requires simultaneous
insertion of two connectors if you're hot plugging.

I mean isn't that what the SATA hot-swap specification calls for?
Nope.

If not, what is the true definition of hot-plugging?

At that mechanical level, the simultaneous
insertion and removal of two connectors.

The short story is that you do need hot swap support in the drive,
the controller. And in the OS if you want to be able to reef the
'sled' out regardless of what the OS is doing with the drive,
so the OS can complete what its currently doing on the drive.

Its probably viable to use a sled that has a clear indication
of drive activity, so you dont actually pull it out when the
OS is using the drive. Thats tricky tho because just because
XP isnt currently using the drive doesnt mean that it wont
try in the instant you have unplugged it. No big deal if its
just doing a read as it does for various reasons, but not
a good idea with a write.

Probably best to concentrate on the sleds themselves and
concentrate on the name brands like Kingwin and only use
a sled thats advertised as supporting hot swapping.

There are some systems that document that quite well with
RAID, but not many at all that do that that with non RAID.

What you are seeing is the classic downsides of operating on the
bleeding edge of computing technology. Quite a bit of bleeding.

 

[J. Clarke]

So you want to be able to pull one SATA drive and push another one under
live Windows XP?
Without any RAID? Without going to "safely remove hardware" or similar
manual procedure?
Without risking of data corruption? You must be dreaming.

You can't just pull and plug, but if you first go to device manager and
disable the drive you are removing and then enable the one you insert the
process goes fine.

 

[Peter]

So you want to be able to pull one SATA drive and push another one under

You can't just pull and plug, but if you first go to device manager and
disable the drive you are removing and then enable the one you insert the
process goes fine.

That's my point. Can't pull a drive without first telling OS about your
intentions.
Unless you do not care about data integrity or have an intelligent RAID
controller.

 

[Curious George]

That's my point. Can't pull a drive without first telling OS about your
intentions.
Unless you do not care about data integrity or have an intelligent RAID
controller.

On Sun, 23 Apr 2006 08:06:53 -0700, "Stan Shankman"

I would like to simply reach over and yank out the removable drive any
time I wish, and replace it with another drive. (Now, if I have to go
to the system tray, and tap on dismount or something like that, so be
it - I just want to know what I must do.)

 

[Stan Shankman]

More Information on SATA Hot-Plugging and Hot-Swapping
______________________________________________

Anna,

Thank you for the reply, and for the link to the SATA-IO organization. That
was particularly helpful.

I suspect that the SATA-IO standard offers a smorgasbord of features from
which the various drive manufactures may choose when designing a new drive.
And that being a flexible standard, not all features are required, and it is
up to the individual drive manufactures to implement whichever features they
desire. Of course I do suspect that there is a set of mandatory features
from which the manufacturer may not vary - if there new drive is to be
considered a true SATA drive. And so 'hot-plugabilty' may just be one of
those elective features. So insofar as the SATA-IO organization is
concerned, one must check with the drive manufacturer to be certain that the
drive in question does, in fact, support 'hot-plugging'. But I further
suspect that the implementation of 'hot-plugability' is so trivial from an
engineering standpoint, and so impelling for other reasons (not the least of
which would be warranty considerations), that no manufacturer has yet chosen
to produce a drive that does not conform to this important feature.

Also, insofar as the 4-pin Molex connector is concerned, I again suspect
that this connector is equally capable of performing the hot-plug function.
Hot-plugabiltiy is, after all, implemented at the *electrical circuit
level* - i.e. those circuits within a device that all external electrical
wiring eventually becomes interfaced to. And since the SATA organization is
laying-out specifications for a new type of drive, it is of little wonder
that they shun the use of non-SATA connectors. It may well be that
mechanical aspects of the newer SATA power-connector have been designed to
accommodate repeated connection-cycling, and that Molex connectors are
considered to simply be a plug-once-and-forget kind of connector.
Nonetheless, from a user standpoint, anyway one can break the connections to
a hot-pluggable device must be expected to be safe if that device is indeed
hot-pluggable.

I also have dreamt-up my own idea as to how SATA hot-swap software should
work:

If one removes a SATA drive at a disadvantageous time, i.e. either a *read*
or a *write* operation should be attempted (or is being attempted) on the
missing drive, then the following recovery path should be initiated.

A. -- WRITE FAILURE

An alert screen should be presented to the user, indicating that: "File
*such-and-such* could not be written to drive *such-and-such* due to the
fact that the drive is offline. - What would you like to do?" - Three
choices should be offered: 1: *CANCEL* the write operation.
2: Re-install the missing drive and hit *RETRY*.
3: *CACHE* the file on the system drive and await the arrive of the missing
drive before finalizing the write operation. (Once the missing drive becomes
available again, only then will the file [or files] be written onto the
re-appeared disk.) This selection should be accompanied with a check-box:
"In the future always do the same for files of size less than: (Here a
user-selectable dropdown menu)." (Personally, I would check the box, and
select a file size of around 10MB from this dropdown.)

B. -- READ FAILURE

"An alert screen should be presented to the user, indicating that: "File
*such-and-such* could not be read from drive *such-and-such* due to the fact
that the drive is offline. - What would you like to do?" - Two choices
should be offered:
1 *CANCEL* the read operation.
2: Re-install the missing drive and hit *RETRY*.

That's all there should be to it. Simple right? Now one can yank out a drive
at any time without worry.

And then there is one new idea I have to offer the standards committee; SATA
drives should have a switch physically located on the drive itself used to
mark the drive *READ ONLY*. If the operating system senses that a SATA drive
is *Read Only* then all appropriate measures should be taken within the
operating system to accommodate that fact. For instance, no attempt should
be made to write a *Drive Signature* or *Thumbnails* or anything like that.
Read-only drives are something from the past, and I think it's about time to
bring them back.

So anyway, enough of my "dreaming". And now, if you wouldn't mind, I would
like to ask you a few questions.


Would you please explain in more detail how you go about swapping out a
disk? Do you use the Disk Management Console? Or what? What specifically do
you do when you remove one drive and install another - and, for the record,
are you talking about a RAID or not? Oh, and please specify which operating
system you are using.


Now I would like to point-out; that of all the replies I have received so
far, no one has addressed the; "What makes a SATA controller hot-pluggable?"
question. Is it just software? Or not?

And then finally, would you please state how satisfied you are with
hot-plugging. - Is it something you would defiantly recommend to others?

Thank you a lot for taking the time to answer these questions. I appreciate
it very much. And I remind you that many more people will find your reply on
Usenet from the Google search engine. And I am sure that they too will thank
you for your wonderful information!

- Stan Shankman

 

[Peter]

USB drives are hot-pluggable. Did you use one before? External USB hard
drives, USB memory sticks, etc. You know what happens when you insert it to
live machine running hot-plug aware OS. You will get a series of
notifications and additional applet which would facilitate safe removal of
such a drive.
Obviously there are many ways to implement it, but you still need to notify
OS about your intention to remove drive. That could be applet dialog or a
custom made script which you can invoke with a single click of a mouse.
Hot-swap term I understand applies only to fault tolerant systems, where
system detects failure, passes control to other/good component, notifies
about failure. Then you swap failed component with a good one (without
shutting down anyting), system detects it and readjusts subsystem settings.
Hot-pluggability is a collaboration between hardware, firmware, drivers and
OS.

 

[Anna]

(In response to Stan Shankman's query re "hot-plugging" SATA HDs)...

to house removable hard drives.

More Information on SATA Hot-Plugging and Hot-Swapping
(SNIP)

So anyway, enough of my "dreaming". And now, if you wouldn't mind, I would
like to ask you a few questions.

Would you please explain in more detail how you go about swapping out a
disk? Do you use the Disk Management Console? Or what? What specifically
do
you do when you remove one drive and install another - and, for the
record,
are you talking about a RAID or not? Oh, and please specify which
operating
system you are using.

Now I would like to point-out; that of all the replies I have received so
far, no one has addressed the; "What makes a SATA controller
hot-pluggable?"
question. Is it just software? Or not?

And then finally, would you please state how satisfied you are with
hot-plugging. - Is it something you would defiantly recommend to others?

Thank you a lot for taking the time to answer these questions. I
appreciate
it very much. And I remind you that many more people will find your reply
on
Usenet from the Google search engine. And I am sure that they too will
thank
you for your wonderful information!

- Stan Shankman

Stan:
As I previously indicated, we usually work with removable HDs - what I
believe you were referring to as "drive sleds". This is still another
advantage of these "mobile racks" in that the user can simultaneously
connect & disconnect the power/signal cables from the SATA drives, thus
meeting the specification for "hot-plugging" capability of SATA hard drives.

The OS is XP in a non-RAID configuration. We haven't worked with SATA HDs to
any degree with prior operating systems.

There is no need to access Disk Management nor Device Manager (as I believe
one or more responders to your query indicated). Presumably when one is
invoking hot-plugging (hot-swapping), he or she is doing so with respect to
a secondary SATA HD. Obviously if the boot drive is disconnected the system
will go down and a reboot would be necessary. So, in the case of using
removable HDs in their mobile racks, it's a simple matter to disconnect the
secondary drive and substitute another in its place and the latter drive
will be recognized by the system. As simple as that.

While we're on this subject let me say a few words about a fairly recent
development which impacts on this hot-plugging (hot-swapping) issue...

A number of motherboards are now coming equipped with an eSATA ("e" for
external) port on the motherboard's backplane. By connecting an ordinary
SATA HD to this port (but note the eSATA port needs a special eSATA
connector on the signal/data cable that will be connected to it - see below)
you now have an *external* device that's treated as an *internal* device by
the system.

Think of the advantages of this. For the first time in an XP environment,
you will be able to directly install the XP OS onto an "external" SATA
drive, i.e., a drive that is physically located outside the computer's case,
and that drive will be bootable. So that the user could *directly* install
the XP OS onto that drive should he or she desire, or (possibly the more
common scenario) be able to clone the contents of one's internal day-to-day
working HD (PATA or SATA) - using a disk imaging program, e.g., Ghost, and
the drive will be bootable - a capability that has eluded us with
USB/Firewire external hard drives up to now. An enormous advantage, no?

Another advantage of using an "external" SATA HD is its speed. It will
operate substantially at the same speed as an internal SATA HD and thus be
considerably faster than a USB/Firewire EHD.

The eSATA port does allow for "hot-swapping" of connected devices assuming
the device itself has no problem with this capability.

Still another advantage of the eSATA port is that it supports the latest
SATA 3 Gb/sec specification.

Actually, you could connect a SATA HD to the eSATA port without the absolute
necessity of containing that drive in any special enclosure. Theoretically
you could plop it in a cigar box or even run the SATA data/signal cable
directly to a bare drive. Not the most desirable thing to do for the average
user, but it can be done. We generally set up our desktop computers with
mobile racks (2) to contain our removable hard drives. It's a hardware
arrangement that we strongly recommend for many desktop computer users. So
we usually contain the "external" SATA drive in one of the removable trays
that are also used in the mobile racks. And, as I previously indicated, this
hardware arrangement lends itself to simultaneous connects/disconnects of
the SATA HD to & from the system.

Now, what about the power to that SATA "external" drive? You simply use the
power from your computer's power supply. There's absolutely no need for an
external power supply. So that's another advantage of this eSATA device,
yes? It's a relatively simple matter for a user to run a power cable from
their PS to the external SATA drive, but it does mean that you have to snake
it out probably through one of the slots on the backplane of the computer's
case. On the other hand, enclosures are now coming onto the market with
direct SATA-to-SATA connection capability that have a built-in power supply.
A number of these now come equipped with eSATA connectors as well.

BTW, there's another device we came across that users may be interested in
to connect an external SATA HD. It's called the SATAPOWPLAT1, manufactured
or distributed by StarTech. Take a look at
$7.99 http://www.buy.com/retail/product.asp?sku=10360812&loc=101&sp=1 and

$5.45 http://www.provantage.com/scripts/cart.dll/x/0/rtspecs/STRT0HA


This device is simply attached to the I/O bracket on the computer case's
backplane. It comes with two external connectors - the SATA data connector
and the 15-pin SATA power connector. Internally (the other side of its slot
plate) is, of course, the SATA data connector and the normal 4-pin Molex
power plug. So it's a simple matter to connect the device to one of the
power leads of one's PS.

Given the significant advantages of an eSATA port connection I would guess
that more & more motherboards will be equipped with this feature since it
inherently has the substantial advantages of treating an "external" device
(the SATA HD) as a normal internal device together with providing superior
performance when compared with USB/Firewire external hard drives.

Our experience to date with "hot-plugging" has been very positive, both with
respect to using that feature with removable HDs and the eSATA feature as
noted above. As I previously stated, over the past year or so we've worked
with a fairly wide variety of SATA HDs and have experienced no problems
involving data corruption nor any physical problems affecting the drives
themselves.
Anna

 

[Rod Speed]

More Information on SATA Hot-Plugging and Hot-Swapping
______________________________________________

Anna,

Thank you for the reply, and for the link to the SATA-IO
organization. That was particularly helpful.

I suspect that the SATA-IO standard offers a smorgasbord of features
from which the various drive manufactures may choose when designing a
new drive. And that being a flexible standard, not all features are
required, and it is up to the individual drive manufactures to
implement whichever features they desire. Of course I do suspect that
there is a set of mandatory features from which the manufacturer may
not vary - if there new drive is to be considered a true SATA drive.
And so 'hot-plugabilty' may just be one of those elective features.
So insofar as the SATA-IO organization is concerned, one must check
with the drive manufacturer to be certain that the drive in question
does, in fact, support 'hot-plugging'. But I further suspect that the
implementation of 'hot-plugability' is so trivial from an engineering
standpoint, and so impelling for other reasons (not the least of
which would be warranty considerations), that no manufacturer has yet
chosen to produce a drive that does not conform to this important
feature.

Also, insofar as the 4-pin Molex connector is concerned, I again
suspect that this connector is equally capable of performing the
hot-plug function. Hot-plugabiltiy is, after all, implemented at the
*electrical circuit level* - i.e. those circuits within a device that
all external electrical wiring eventually becomes interfaced to.

Nope, the other factor with hot plugability is to connect
the ground first before connecting the powered pins.

And since the SATA organization is laying-out specifications
for a new type of drive, it is of little wonder that they shun the
use of non-SATA connectors. It may well be that mechanical
aspects of the newer SATA power-connector have been
designed to accommodate repeated connection-cycling,
and that Molex connectors are considered to simply be
a plug-once-and-forget kind of connector.

Well, plug a few times, anyway.

Nonetheless, from a user standpoint, anyway one can
break the connections to a hot-pluggable device must be
expected to be safe if that device is indeed hot-pluggable.

Its more complicated than that with connecting the ground first.

I also have dreamt-up my own idea as to
how SATA hot-swap software should work:

If one removes a SATA drive at a disadvantageous time,
i.e. either a *read* or a *write* operation should be
attempted (or is being attempted) on the missing
drive, then the following recovery path should be initiated.

Makes a lot more sense to do it the way the other removables
do, tell the OS that you want to unplug it and have it tell you
when thats acceptible at the drive activity level.

A. -- WRITE FAILURE

An alert screen should be presented to the user, indicating that:
"File *such-and-such* could not be written to drive *such-and-such*
due to the fact that the drive is offline. - What would you like to
do?" - Three choices should be offered: 1: *CANCEL* the write
operation. 2: Re-install the missing drive and hit *RETRY*.
3: *CACHE* the file on the system drive and await the arrive
of the missing drive before finalizing the write operation.

Too much of a risk of the system falling
over before the drive shows up again.

(Once the missing drive becomes available again, only then
will the file [or files] be written onto the re-appeared disk.)
This selection should be accompanied with a check-box:
"In the future always do the same for files of size less than:
(Here a user-selectable dropdown menu)." (Personally,
I would check the box, and select a file size of around
10MB from this dropdown.)

Too messy, and clearly they chose not to go
that route with the other removable drives.

Why change now with SATA ?

B. -- READ FAILURE

"An alert screen should be presented to the user, indicating that:
"File *such-and-such* could not be read from drive *such-and-such*
due to the fact that the drive is offline. - What would you like to
do?" - Two choices should be offered:
1 *CANCEL* the read operation.
2: Re-install the missing drive and hit *RETRY*.

That's all there should be to it. Simple right?

Nope, simpler to do it the way other removables do it now.

Now one can yank out a drive at any time without worry.

They chose not to go that route with the other removables.

And then there is one new idea I have to offer the standards
committee; SATA drives should have a switch physically located on the
drive itself used to mark the drive *READ ONLY*. If the operating
system senses that a SATA drive is *Read Only* then all appropriate
measures should be taken within the operating system to accommodate
that fact. For instance, no attempt should be made to write a *Drive
Signature* or *Thumbnails* or anything like that. Read-only drives
are something from the past, and I think it's about time to bring
them back.

That stuff should be an OS level function, not a drive physical level
function.

So anyway, enough of my "dreaming". And now, if you
wouldn't mind, I would like to ask you a few questions.

Would you please explain in more detail how you go about swapping out
a disk? Do you use the Disk Management Console? Or what? What
specifically do you do when you remove one drive and install another
- and, for the record, are you talking about a RAID or not? Oh, and
please specify which operating system you are using.

Now I would like to point-out; that of all the replies I have
received so far, no one has addressed the; "What makes a SATA
controller hot-pluggable?" question. Is it just software? Or not?

Not. The controller needs to be able to handle the situation
where the drive goes missing part way thru a write.

 

[Stan Shankman]

Anna,

Wow! You pretty much have quenched any hesitation I have had in setting up a
SATA hot-swap environment on my PC! Thanks!
I will be ordering my removable drive fixtures now.

But if you wouldn't mind, their is one last question I have for you:
What will happen in your systems if you inadvertently remove a hard drive
while a write or read operation is underway?


And I remind you that it is difficult to locate SATA specifications for the
built-in motherboard controllers.
For the record, can you share with us which motherboards you have had good
luck with? (or chipsets) And can you tell us if you have found any
motherboards with ill performing SATA controllers?

Otherwise, thanks to you, I'm almost out of questions and am ready to go
ahead and start setting-up my SATA farm!!

You have been very helpful.

- Stan Shankman

 

[Anna]

See my inline comments...

Anna,

Wow! You pretty much have quenched any hesitation I have had in setting up
a
SATA hot-swap environment on my PC! Thanks!
I will be ordering my removable drive fixtures now.

Good. I think you'll be happy with the results. Where portability is an
issue, we rarely use USB/Firewire external hard drives any more, much
preferring to use the SATA drive as an external device (with a SATA-to-SATA
connection, of course) because of its superior performance as compared with
the USBEHDs, as I described earlier. Otherwise we're strong proponents of
equipping one's desktop PC with two removable HDs as we previously
discussed, so that the SATA hot-swapping capability is easily achieved with
the secondary HD.

But if you wouldn't mind, their is one last question I have for you:
What will happen in your systems if you inadvertently remove a hard drive
while a write or read operation is underway?

I would think you would get some data corruption but then again, maybe not.
We've never run into this problem when "hot-swapping" but I must add that we
don't just willy-nilly disconnect the drive while it's apparently doing its
work.

And I remind you that it is difficult to locate SATA specifications for
the
built-in motherboard controllers.

If the motherboard supports the SATA 3 Gb/s data transfer interface
(so-called "SATA-II"), it's a virtual certainty the "hot-plugging"
capability will be supported. And in many instances the specifications
listed on the manufacturer's website (or in the online user manual) will
include this information. And, of course, you can directly check with the
manufacturer.

For the record, can you share with us which motherboards you have had good
luck with? (or chipsets) And can you tell us if you have found any
motherboards with ill performing SATA controllers?

We're particularly oriented towards ASUS motherboards but have used or had
experience with many other makes. I really can't single out any particular
motherboard make or model in any negative way re this issue.
Anna