[plug] Re: drive issues

[Craig Ringer]

> JLM>  Some of the servers I've had to build when I worked for an large IT firm had as many as 12 or more hot swap drives and 2-4 DLT units in the one box.  On another system it was a SANS unit with 1.3TB of 18GB drives in it with 4-6 PSU and this was hooked up to a server with 12 drives in it. Again it comes down to what the needs are.  This unit was running multiple RAIDS (stripe and redundancy) and it was hooked to the server via a fibre channel card.  even with huge capacity drives the server has to be able to deliver the data in a timely manner.  If it's just huge amount of online storage capacity then a SANS would be the answer with Gbit data transfer rate.  Price is always the issue, but bottom line is you get what you pay for.

There we have it. "large IT Firm". You can't say "if you can't afford a 
big beasty server with 10 times the grunt you'll ever need, you can't 
have a reliable server either." /I've/ never worked on a machine with 
more than 8 drives, because I don't work with /big/ hardware for /big/ 
companies.

> JLM> So I've heard, but give me a server with Hot Swap and several Hot Swap PSU and Hot Swap NIC and we can rock and roll.  Once you've worked on one it pretty hard to accept anything less that this (IMO).  But like the man said "champagne taset on beer pocket money".

Sure. Just give me the money to buy one ;-/
Therein being the problem. Its hard to justiy SCSI for this box, and 
other hot-swappable components would silly. We can deal with the 10 mins 
of downtime it takes to swap a failed PSU. If a company can't, then sure 
get one - but it comes back to cost/benefit again.


JLM>  But there is no advantage to using SATA currently since the bus is 
PCI and the drives are still ATA100 campatible, why pay more for the 
same?  I'll wait for the subsystem to change.

For the drives:
http://google.com/search?q=serial+ata+seagate+barracuda
http://google.com/search?q=western+digital+raptor

Very much SATA native, esp. the Raptor series. Not that it matters - not 
even high performance 15k RPM drives could flood an ATA133 bus's 
available bandwidth. One Seagate Cheeta 15k can manage about 42mb/s - 
and that's seagate marketing talking.

Bus:
I presume you're talking about a PCI bus as opposed to PCI-X. The 
bandwidth of  66Mhz/64bit PCI is more than adequte to handle the 
thoughput from quite a few (S)ATA drives - and SCSI drives for that 
matter. If you need a PCI-X SCSI adapter, your needs are in the area 
where money for hardware is getting irrelevent. You can't hope to flood 
a 66/64 with 4 SCSI drives, or even 8 under real world performance levels.

It doesn't really matter, anyway. You get what you think is worth the 
money, and will provide appropriate returns in performance, reliability, 
and capacity. For my needs at home, SCSI would be silly. SCSI raid 
doesn't satisfy the "price per capacity" requirement at work so its ATA 
for me. However, if you or your employer find that for your needs and 
applications its worth paying 4x as much for the same capacity (with 
better performance and MTBF) that's fair enough too.

Lets stop boring the list.