various questions about Sata.

  • Thread starter Thread starter DEMAINE Benoit-Pierre
  • Start date Start date
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DEMAINE Benoit-Pierre

I thought SATA.1 was different from SATA.2, and only the latter one could perform
NCQ (queue querry reordering), when some people said me it is just a matter of speed.

Will SATA.3 be chainable/serialisable ?
(problems inherent to serialisable devices are offtopic)
when will that come out ?
will SATA.2 host controller be compatible with that ?

is SATA hotplug ?
hot swap ?
( I do make a difference)

Thx
 
Both NCQ at least with newer SATA 150 models.

Both Hot swappable.

Both fast. Though they would never get about 150MBS and SATA drive
can't do it.

SATA 3, well i have NO IDEA. Somone else will have to answer that.

Bye.
 
DEMAINE Benoit-Pierre said:
I thought SATA.1 was different from SATA.2, and only the latter one could perform
NCQ (queue querry reordering), when some people said me it is just a matter of speed.
Click to expand...

Several hard disk manufacturers sell drives that do NCQ but only
150MB/S (not 300MB/s) as SATA2 drives, because NCQ is a SATA2 feature.
Given that the drives can sustain at best 70MB/s or so, the faster
interface is not really useful for these drives anyway, whereas NCQ
may be (depending on your host adapter and OS).

- anton
 
Given that the drives can sustain at best 70MB/s or so, the faster
interface is not really useful for these drives anyway, whereas NCQ
may be (depending on your host adapter and OS).
Click to expand...

when serial chain will come out, chaining 4 drives capable of 70 each will require
280 ... if the concentrator or any midle disk is limitted to 150, the whole chain
will slow down.

300 can only stand 4 drives, when RAID.5 usually want 5 or 9 drives ... or it will
saturate.
 
DEMAINE Benoit-Pierre said:
when serial chain will come out, chaining 4 drives capable of 70 each will require
280 ... if the concentrator or any midle disk is limitted to 150, the whole chain
will slow down.
Click to expand...

But I guess you won't be able to use the drives I was referring to in
a chain anyway (except maybe at the end), but will need new,
chain-capable drives, so even present-day 300MB/s will not be chained,
right?

- anton
 
DEMAINE said:
when serial chain will come out,
Click to expand...

What leads you to believe that that is _ever_ going to happen?
chaining 4 drives capable of 70 each will
require 280 ... if the concentrator or any midle disk is limitted to 150,
the whole chain will slow down.
Click to expand...

Since there is no way to make a 150 MB/sec disk the "middle disk" this is a
non-issue. No _current_ SATA disk will would work in such a chain.
300 can only stand 4 drives, when RAID.5 usually want 5 or 9 drives ... or
it will saturate.
Click to expand...

What leads you to believe that RAID 5 "usually want 5 or 9 drives"? RAID 5
needs at least 3 drives and beyond that there are no magic numbers. In any
case, SATA RAID controllers have one drive per channel and I see no reason
why that would change even if some new variant of SATA that supports
chaining became available. The cost savings would be negligible by that
time.
 
when serial chain will come out,
What leads you to believe that that is _ever_ going to happen?
Click to expand...

Yes, that was said to be planed for SATA.3 even before any SATA was available in
shop ... I do hope that for end 2006 or begin 2007.
What leads you to believe that RAID 5 "usually want 5 or 9 drives"? RAID 5
needs at least 3 drives and beyond that there are no magic numbers. In any
case, SATA RAID controllers have one drive per channel and I see no reason
why that would change even if some new variant of SATA that supports
chaining became available. The cost savings would be negligible by that
time.
Click to expand...

It shall change because from memory it is planed to change. I dont really love the
idea of pluging 5 9 or more than 13 disks to my host ... because even when the SATA
plug is very small, 12 16 or 20 plugs on a board will take very much room ...

serialisable SATA would then look to me a bit more like SCSI ... and I really hope
they wont put stupid limits like for P-IDE (2) or USB (5 layers, when in fact no
single device is sold te be serialisable [except Apple keyboards of course]). I
shall check for personnal interest what are the limits of FireWire.
 
DEMAINE Benoit-Pierre said:
Yes, that was said to be planed for SATA.3 even before any SATA was available in
shop ... I do hope that for end 2006 or begin 2007.
Click to expand...
There is no need for this stupidity. Chained SATA will NOT handle failures gracefully.

SATA2 port multipliers (4/5 way) are available today.
Unfortunately they only work with SiI SATA2 and better RAID controller.
 
DEMAINE said:
Yes, that was said to be planed for SATA.3 even before any SATA was
available in shop ... I do hope that for end 2006 or begin 2007.
Click to expand...

Said by who? The only mention I can find of such a thing is this thread and
one assertion that SATA2 has that feature, which it does not.
It shall change because from memory it is planed to change.
Click to expand...

Do you have a link for that?
I dont really
love the idea of pluging 5 9 or more than 13 disks to my host ... because
even when the SATA plug is very small, 12 16 or 20 plugs on a board will
take very much room ...
Click to expand...

If the board is going to support 16 drives it will likely have a multilane
connector anyway.
serialisable SATA would then look to me a bit more like SCSI ... and I
really hope they wont put stupid limits like for P-IDE (2) or USB (5
layers, when in fact no single device is sold te be serialisable [except
Apple keyboards of course]). I shall check for personnal interest what are
the limits of FireWire.
Click to expand...

How do you hot-swap a daisy-chained drive? I'm sorry, but this looks like a
non-starter to me.
 
Eric Gisin said:
There is no need for this stupidity. Chained SATA will NOT handle failures gracefully.

SATA2 port multipliers (4/5 way) are available today.
Unfortunately they only work with SiI SATA2 and better RAID controller.
Click to expand...

And are more expensive than the controller that they are supposed to spare.
 
J. Clarke said:
Said by who? The only mention I can find of such a thing is this thread and
one assertion that SATA2 has that feature, which it does not.


Do you have a link for that?


If the board is going to support 16 drives it will likely have a multilane
connector anyway.
Click to expand...

It already has: the Infiniband connector.
serialisable SATA would then look to me a bit more like SCSI ... and I
really hope they wont put stupid limits like for P-IDE (2) or USB (5
layers, when in fact no single device is sold te be serialisable [except
Apple keyboards of course]). I shall check for personnal interest what are
the limits of FireWire.
Click to expand...

How do you hot-swap a daisy-chained drive?
Huh?

I'm sorry, but this looks like a non-starter to me.
Click to expand...
 
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