3.5" SATA->USB drive enclosure with good cooling?

[Paul Rubin]

I have a cheap 3.5" ATA drive enclosure with a small fan (40mm or so)
and it gets noticably warm when the drive stays active for a while
(Seagate 160gb drive, I think 7200.9 but am not sure). I figure the
even cheaper fanless enclosures may be even worse.

I have an application that will pound the heck out of the drive 24/7
for quite a long while so I'm thinking of getting one of those WD
Raptor SATA drives intended for server deployment. Are they ok? And
what kind of case should I put it in? I figure it will need much more
serious cooling than the enclosure I'm using now. The host computer
is a laptop so a USB case is really easier to deal with than other
possible methods of connecting up the drive. (I guess Firewire is ok
too--I can use a Cardbus adapter to connect it)

 

[Rod Speed]

I have a cheap 3.5" ATA drive enclosure with a small fan (40mm
or so) and it gets noticably warm when the drive stays active for
a while (Seagate 160gb drive, I think 7200.9 but am not sure).
I figure the even cheaper fanless enclosures may be even worse.

Not always, its certainly possible to conduct the heat away
from a drive that doesnt generate as much heat, to a decent
heavy metal enclosure that itself gets rid of the heat to the air.

I have an application that will pound the heck out of the drive 24/7
for quite a long while so I'm thinking of getting one of those WD
Raptor SATA drives intended for server deployment. Are they ok?

That would only make much sense if its an eSATA enclosure.

And what kind of case should I put it in? I figure it will need
much more serious cooling than the enclosure I'm using now.

You can get multiple drive cases which are quite
compact and which have a decent fan in them.

The host computer is a laptop so a USB case is really easier to
deal with than other possible methods of connecting up the drive.

No point in paying extra for a Raptor with USB
because that will cripple the thruput severely.

(I guess Firewire is ok too--I can use a Cardbus adapter to connect it)

Ditto. You can get eSATA cardbus adapters now.

 

[Paul Rubin]

Not always, its certainly possible to conduct the heat away
from a drive that doesnt generate as much heat, to a decent
heavy metal enclosure that itself gets rid of the heat to the air.

Hmm, ok, though the ones I've seen are pretty flimsy.

No point in paying extra for a Raptor with USB
because that will cripple the thruput severely.

I guess I'm not too worried about throughput. The application is seek
intensive but doesn't have to transfer all that much data. The point
of the Raptor is mostly that it's (hopefully) made to put up with long
periods of nonstop seeking, unlike desktop drives. The higher
rotational speed also helps with latency.>

You can get multiple drive cases which are quite compact and which
have a decent fan in them.

I guess that might be ok though besides being bigger and noisier, I
bet they cost more. I'll check.

Ditto. You can get eSATA cardbus adapters now.

Good point, I should check into those and whether there's reasonable
Linux support for them.

Thanks.

 

[Rod Speed]

Hmm, ok, though the ones I've seen are pretty flimsy.

Sure, but there are a few that do have heavy guage extruded aluminium bodys.

I guess I'm not too worried about throughput.

Then there isnt any point in paying extra for a Raptor with its
higher price and higher power use which just makes cooling harder.

The application is seek intensive but doesn't have to transfer all that much
data. The point of the Raptor is mostly that it's (hopefully) made to put up
with long periods of nonstop seeking, unlike desktop drives.

Desktop drives handle that fine.

The higher rotational speed also helps with latency.

That will get swamped by the USB latency.

I guess that might be ok though besides being bigger
and noisier, I bet they cost more. I'll check.

Yeah, they arent the mass market product.

Good point, I should check into those and whether
there's reasonable Linux support for them.

Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

 

[Paul Rubin]

Desktop drives handle that fine.

Hmm, I've always heard the opposite, e.g.

http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf


HTML version:
http://www.usenix.org/events/fast/tech/full_papers/anderson/anderson_html/index.html

talks about the physical differences between desktop and so-called
enterprise drives. My impression is desktop drives are built for
continuous powerup (spinning) but not continuous seeking/transfer, and
they fail quickly in server applications. Are the manufacturers
scamming us? Server drives are at least as expensive per GB as
desktop drives.

That will get swamped by the USB latency.

Interesting, I didn't realize USB added much latency. Hmm. How about
firewire?

Good point, I should check into those [eSata] and whether
there's reasonable Linux support for them.

Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

Firewire may be my best bet. The built-in USB is sure convenient though.

 

[Paul Rubin]

Server drives are at least as expensive per GB as desktop drives.

Heh, editing error, it's still a true statement as is, but I meant to
say "at least 3x as expensive per GB as desktop drives".

 

[Arno Wagner]

Hmm, I've always heard the opposite, e.g.

http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf

That is historic. Cooled well, you can seek al you like on a modern
desktop drive. In fact the Raptor may be more problematic,
since it gets warmer. And the only speed advantage you get
is basically the latency. Are you sure you want to pay
a lot for 25% better latency?

Arno

HTML version:
http://www.usenix.org/events/fast/tech/full_papers/anderson/anderson_html/index.html

talks about the physical differences between desktop and so-called
enterprise drives. My impression is desktop drives are built for
continuous powerup (spinning) but not continuous seeking/transfer, and
they fail quickly in server applications. Are the manufacturers
scamming us? Server drives are at least as expensive per GB as
desktop drives.

Interesting, I didn't realize USB added much latency. Hmm. How about
firewire?

Not better either.

Good point, I should check into those [eSata] and whether
there's reasonable Linux support for them.

Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

Firewire may be my best bet. The built-in USB is sure convenient though.

No. USB and dfirewire add their own layers and have negothiation
and encapsulation overheads.

Arno

 

[Arno Wagner]

Heh, editing error, it's still a true statement as is, but I meant to
say "at least 3x as expensive per GB as desktop drives".

Actually they are not. The Seagate ES drives are certeinly
server drives, but cost about 5% more. They are not _faster_,
but many servers do not need to be that fast. I think your
knowledge about drives is a bit outdated. What you say would
have been correct 5 years ago, but not so anymore.

As to the Raport, I believe it is basically an expensive toy
for speed freaks, but mostly a waste of money.

Arno

 

[Rod Speed]

Hmm, I've always heard the opposite, e.g.

http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf

Doesnt say anything like that.

HTML version:
http://www.usenix.org/events/fast/tech/full_papers/anderson/anderson_html/index.html

talks about the physical differences between desktop and so-called
enterprise drives. My impression is desktop drives are built for
continuous powerup (spinning) but not continuous seeking/transfer,

You're just plain wrong.

and they fail quickly in server applications.

There in spades.

Are the manufacturers scamming us?

Nope, the 'enterprise' drives are different in other respects.

Server drives are at least as expensive per GB as desktop drives.

It would be a hell of a lot more surprising if they
werent given the much lower volume of them sold.

Interesting, I didn't realize USB added much latency. Hmm. How about firewire?

Its better but it would still swamp any advantage that a raptor would have.

Good point, I should check into those [eSata] and
whether there's reasonable Linux support for them.

Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

Firewire may be my best bet. The built-in USB is sure convenient though.

Yeah, really depends on how much you care about the overheads involved.

The difference stands out like dogs balls.

 

[Rod Speed]

Heh, editing error, it's still a true statement as is, but I meant
to say "at least 3x as expensive per GB as desktop drives".

Again, it would be a hell of a lot more surprising if
they werent given the difference in volumes shipped.

 

[Paul Rubin]

Actually they are not. The Seagate ES drives are certeinly
server drives, but cost about 5% more. They are not _faster_,

Are you serious? That's very interesting. Just a year or so ago I
remember looking at a desktop drive and a server drive in the store,
with the server drive having quite a bit lower capacity. Both had the
same 3.5" form factor but the server drive weighed about 1.5x as much.

but many servers do not need to be that fast. I think your
knowledge about drives is a bit outdated. What you say would
have been correct 5 years ago, but not so anymore.

I guess that "more than an interface" paper might be 5yo by now but
this is still pretty counterintuitive. The cost differential between
the ES drives and speed freak server drives is so large that you can
get the speed back by striping your data across 2x or 3x as many ES
drives. Anyway the ES drive is something to consider. Thanks.

 

[Paul Rubin]

That is historic. Cooled well, you can seek al you like on a modern
desktop drive. In fact the Raptor may be more problematic,

I'm behind the times. Thanks.

is basically the latency. Are you sure you want to pay
a lot for 25% better latency?

No I don't, I can see paying something for it but not a lot.

 

[Arno Wagner]

Are you serious? That's very interesting.

They are basically selected for low vibration. ES for Enterprise
Storage...

Just a year or so ago I
remember looking at a desktop drive and a server drive in the store,
with the server drive having quite a bit lower capacity. Both had the
same 3.5" form factor but the server drive weighed about 1.5x as much.

Well, maybe some shop was selling it sold drives at a high price
with some fancy label?

I guess that "more than an interface" paper might be 5yo by now but
this is still pretty counterintuitive. The cost differential between
the ES drives and speed freak server drives is so large that you can
get the speed back by striping your data across 2x or 3x as many ES
drives. Anyway the ES drive is something to consider. Thanks.

Speed freaks are not rational. People that need fast disks go
for U320 or U160 SCSI drives. Speed freaks are similar to
people that buy cheap high-powerd cars.

Arno

 

[Folkert Rienstra]

That is historic.

Cooled well,

As in refrigurated.

you can seek al you like on a modern desktop drive.

If a drive wasn't build to transfer the heat away from
where it does the most damage you can cool it all you like.

In fact the Raptor may be more problematic, since it gets warmer.

The Raptor also has it's own inbuilt dissipation fins.

And the only speed advantage you get is basically the latency.

And the better seek performance.

Are you sure you want to pay a lot for 25% better latency?

How about the almost 100% better seek performance, babblebot?

Raptor avg seek 4.6 ms avg latency 3 ms 7.6 ms total avg acccess
WD RE avg seek 8.9 ms avg latency 4.2 ms 13.1 ms total avg acccess
Seag.ES avg seek 8.5 ms avg latency 4.2 ms 12.7 ms total avg acccess


Lets assume they can all do ~80MB/s.
Lets assume USB can do 30MB/s (50% overhead).
Let's assume random access.

Raptor:
8kB transfers in .1 ms, the file transfers in 7.6 + .1 ms = 7.7 ms,
avg transfer rate is 8,000/(7.7/1000) = 1.04 MB/s
ES:
8kB transfers in .1 ms, the file transfers in 12.7 + .1 ms = 12.8 ms,
avg transfer rate is 8,000/(12.8/1000) = .63 MB/s

Raptor about 66% faster.


Raptor:
80kB transfers in 1 ms, the file transfers in 7.6 + 1 ms = 8.6 ms,
avg transfer rate is 80,000/(8.6/1000) = 9.3 MB/s
ES:
80kB transfers in 1 ms, the file transfers in 12.7 + 1 ms = 13.7 ms,
avg transfer rate is 80,000/(13.7/1000) = 5.8 MB/s

Raptor about 50% faster


Raptor:
800kB transfers in 10 ms, the file transfers in 7.6 + 10 ms, = 17.6 ms
avg transfer rate is 800,000/(17.6/1000) = 45 MB/s
ES:
800kB transfers in 10 ms, the file transfers in 12.7 + 10 ms, =22.7 ms
avg transfer rate is 800,000/(22.7/1000) = 35 MB/s

Both equally fast while limited by USB bandwidth.


Raptor:
400kB transfers in 5 ms, the file transfers in 7.6 + 5 ms, = 12.6 ms
avg transfer rate is 400,000/(12.6/1000) = 31 MB/s
ES:
400kB transfers in 5 ms, the file transfers in 12.7 + 5 ms, = 17.7 ms
avg transfer rate is 400,000/(17.7/1000) = 23 MB/s

Raptor still about 35% faster than ES and using full available USB
bandwidth.
Presumably the switch point where both become equally fast on USB
is somewhere around 600kB and bigger sized files.

Arno



Nope.

It doesn't any more than SATA does. And it's not latency, it's overhead.
What matters is the usable bandwidth that remains after you deduct the
overhead.

Hmm. How about firewire?

Not better either.

Good point, I should check into those [eSata] and whether
there's reasonable Linux support for them.

Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

Firewire may be my best bet. The built-in USB is sure convenient though.

No. USB and dfirewire add their own layers and have negothiation
and encapsulation overheads.

Right, so best stay away from SATA too.

Babblebot, clueless as always.

 

[Folkert Rienstra]

They are basically selected for low vibration.

Fat lot that will do you then.

ES for Enterprise Storage...

Well, maybe some shop was selling it sold drives at a high price
with some fancy label?

Proofreading, who needs it.

Speed freaks are not rational.

Presumably they are modelled after you then.

People that need fast disks go for U320 or U160 SCSI drives.

Because they are 10 and 15k rpm and fast seekers, not because they are
SCSI.

Speed freaks are similar to people that buy cheap high-powerd cars.

Presumably because they can't afford Ferraris and Lambos.

 

[Folkert Rienstra]

Are you serious? That's very interesting. Just a year or so ago I
remember looking at a desktop drive and a server drive in the store,
with the server drive having quite a bit lower capacity. Both had the
same 3.5" form factor but the server drive weighed about 1.5x as much.

You're talking about SCSI, he's not.

I guess that "more than an interface" paper might be 5yo by now but
this is still pretty counterintuitive.

So he's babblebot.

The cost differential between the ES drives and speed freak server
drives is so large that you can get the speed back by striping your
data across 2x or 3x as many ES drives.

But doesn't do anything for your random access speed.

 

[Folkert Rienstra]

Doesnt say anything like that.



You're just plain wrong.


There in spades.


Nope, the 'enterprise' drives are different in other respects.


It would be a hell of a lot more surprising if they
werent given the much lower volume of them sold.

It doesn't. It has protocol overhead, as does every bus.
That's discounted in a higher clockrate.
One reason why you can't directly compare clockrates (Mb/s) of buses.

Hmm. How about firewire?

Its better but it would still swamp any advantage that a raptor would have.

Not on random access it won't.

Good point, I should check into those [eSata] and
whether there's reasonable Linux support for them.
Dunno on that last. That would certainly allow you to
drive the Raptor like its an internal drive performance wise.

Firewire may be my best bet.

Why, if you still have to buy a converter?

The built-in USB is sure convenient though.

Yeah, really depends on how much you care about the overheads involved.

The difference stands out like dogs balls.

Whatever that's supposed to mean.

 

[Paul Rubin]

Well, maybe some shop was selling it sold drives at a high price
with some fancy label?

No I really meant it WEIGHED 1.5x as much. I.e. the mechanical parts
and casing were heavier.

 

[Paul Rubin]

But doesn't do anything for your random access speed.

It doesn't help the latency for a completely serial workload, but it
lets you do seeks in parallel when the workload allows it.

 

[Folkert Rienstra]

It doesn't help the latency for a completely serial workload,
but it lets you do seeks in parallel when the workload allows it.

That assumes files smaller than your stripe (so out goes the multi-
plication of transfer speed for that file) AND not on the same
drive as well (so you depend on chance).
It probably also means that you need a quite expensive RAID
controller to even support that and to rearrange the queues in
order to maximize parallel execution. It also assumes busy server workload to keep the queues filled.

Suddenly that Raptor doesn't look so expensive anymore.