Is it possible to make removeable hard drives hot swap?

[Folkert Rienstra]

Some racks claim that theirs are hot swappable, though...
for IDE hard disks.

Like I said, depends on what you consider hotswap.
When you mention removable racks you obviously mean something
else than removal/insertion without switching the system off.
Half or more of those racks allow (more or less save) removal/insertion
(hotplug?) when system is still powered by using a seperate power switch.

There are racks from Promise that provide hotswap.
They probably will make hotswap save (not affect the bus going
dead or unreliable) by using some circuitry that seperates drives
from the IDE bus. They probably come with extra software or
extension drivers that makeup for the lack of hotswap support
in the drive firmware and the OS.

 

[J.Clarke]

Comparing the amount of time it would take to
copy the files rather than use them on the original
disk. I see what you mean though, and I did not
know that 1G was faster than the hard drives
ability to write the files. Is that true of the faster
SATA drives also?

Most SATA drives are not faster than their PATA equivalents. The WD
Raptor, which is available only as an SATA drive, which is the only
10,000 RPM ATA drive on the market, and which is the fastest
available ATA drive, has a maximum transfer rate of 816 Mb/sec--that's
for single-track transfers on the outermost track and does not consider
seek times. The SATA interface can handle more, it can go as high as
1.2 gigabits/sec, but no drive on the market can come close to achieving
that transfer rate for more than the fraction of a second it takes to
empty the buffer. Even if it did, the standard PCI bus would still be
the bottleneck--it can transfer at most 1.2 billion bits/sec--in the
real world it can generally move about 400 million bits/sec from one
device to another--it uses 400 Mb/sec of its 1.2 billion to read,
another 400 to write, and the remaining 400 for overhead.

 

[J.Clarke]

Thanks : -). I'm not sure what a crossover switch is. I guess
I can put the IDEs in a firewire case.

It's a clumsy solution--if you want to physically swap SATA drives then
the best solution is a hot-swap cage in each machine--there are several
on the market--google "SATA hot-swap cage" and you'll find them.

 

[Not so quick]

SATA.

You need more than just SATA connectors for SATA hotswap.
You basically need the drive mounting hardware and rails etc
as well. They're not currently very common at all.


The problem is finding the hardware that allows SATA hotswap currently.

It is a better approach if you can tho.

Wouldn't the adaptor from SATA to IDE make it
possible to use an IDE mobile thing?

 

[Not so quick]

Why would gigabit NICs be "way to slow"? With gigabit the bottlenecks
are the disk interface and the PCI bus, not the NIC.



--

Comparing the amount of time it would take to
copy the files rather than use them on the original
disk. I see what you mean though, and I did not
know that 1G was faster than the hard drives
ability to write the files. Is that true of the faster
SATA drives also?

 

[Not so quick]

Not a bad idea.


It would be noticeably slower but mechanically
much more convenient because you wouldnt
have to do anything mechanically.

Only you can really say how much the pause
between video capture sessions matters.

You could also do the hotswap using an external firewire
drive. That would be much more viable than with an IDE drive.
And mechanically more convenient than with an SATA drive,
you'd just plug the external drive between the two PCs.
And thats got rather more convenient OS level support too.

You could probably have a pair of external firewire drives
and a crossover switch which swaps the drives between
the PC for an instant switch of the drives between PCs
too. That would certainly be much faster than 1Gb lan.

Thanks : -). I'm not sure what a crossover switch is. I guess
I can put the IDEs in a firewire case.

 

[Arno Wagner]

Maybe I should explain my problem and
see if there is a better solution than hot
swapping. I capture video in about 10G
files. The are converted from avi to mpeg
on a different computer than they are
captured on. I guess 1Gig NICs would be
way to slow.
Thanks : -)

Given that the PCI-Bus only does a theoretical maximum of 135MB/s
(that is 1.08Gb/s), Gigabit NICs should be fine. You cannot
read/write your disks that fast anyway, unless you have
Ultra 160/320 SCSI in a RAID-0 configuration.

Arno

 

[Rod Speed]

Wouldn't the adaptor from SATA to IDE make it
possible to use an IDE mobile thing?

Nope, the connectors on the drive are completely different.

 

[Rod Speed]

Thanks : -). I'm not sure what a crossover switch is.

You have two external drives and two PCs.
In one switch position, Drive A is connected to PC A and Drive B to PC B.
In the other, Drive A is connected to PC B and Drive B to PC A

I guess I can put the IDEs in a firewire case.

Yep, and thats a proper formal standard, unlike the
kludge seen with removable drive bays for IDE drives.

hotswap is part of the standard with firewire
and is more simply implemented in XP etc.

 

[Folkert Rienstra]

Given that the PCI-Bus only does a theoretical maximum of 135MB/s
(that is 1.08Gb/s), Gigabit NICs should be fine.

Completely mangled. Not only is that 1Gb/133MB/s not available for data only,
the PCI bus is the bottleneck as it has to be shared by the storage subsystem
and the network. That leaves 60MB/s, tops.

You cannot read/write your disks that fast anyway, unless you have
Ultra 160/320 SCSI in a RAID-0 configuration.

Obviously you don't need RAID to fill that 60MB/s.

 

[Peter Martin]

It's a clumsy solution--

Bullshit. Much easier than physically swapping drives.

if you want to physically swap SATA drives then the
best solution is a hot-swap cage in each machine--

Bullshit. Much simpler to flick a switch than to physically
remove and replace two drives and risk dropping them.

 

[Folkert Rienstra]

Most SATA drives are not faster than their PATA equivalents.
The WD Raptor, which is available only as an SATA drive,

which is the only 10,000 RPM ATA drive on the market,

and which is the fastest available ATA drive,

Nope, not that one. The new 72 GB Raptor is. The old 36 GB
Raptor is equally fast as a Seagate 7200.7 or a Maxtor Plus 9.

has a maximum transfer rate of 816 Mb/sec--that's for single-track

Measured internally, like Mb/s suggest.

transfers on the outermost track and does not consider seek times.

And it is just that, a number without further user significance.

The SATA interface can handle more, it can go as high as 1.2 gigabits/sec,

But not user data, that's just clock (10->8-bit adjusted, but still clock).

but no drive on the market can come close to achieving that transfer rate
for more than the fraction of a second it takes to empty the buffer.

Which is why we call that burst rate.

 

[Not so quick]

They are IDE.

Thanks : -)

Thanks for the help in several forums. I bought an external
case that uses USB2 and firewire. Expensive but I can put
a CD burner or DVD later.