[plug] SATA & Debian

[Craig Ringer]

Tim Bowden wrote:
>> 3ware RAID will cost around $1100 depending. The one i bought can handle
>> up to 8 HDD. We put 4x120 GB SATA HDDs RAID 5 and hotswapable.  The 
>> motherboard is an intel entry server board, with PATA and SATA. so
>> i guess i can have around 16 HDDs if i wanted. We have found the entry
>> server boards to be quite reliable so far. NICs e100 and e1000 onboard.
>>
> There goes the budget...  Perhaps I should have said "very small file 
> server"  2 x 80 gig mirrored disks will provide us with more storage 
> than we can possibly use.  Looks like that one is well out of reach...

I suggest, then, rethinking your choice of SATA. You can very cheaply 
use basic PATA software RAID, or if you like you can use "hardware 
assisted" (*ick*) software RAID like the HighPoint and Promise 
controllers built-in to many motherboards.

If you're working to that kind of a budget, I question the utility of 
SATA. Unless you need hot-swap support, you probably won't gain much 
from it. SATA TCQ is only supported in some of the newest drives like 
Western Digital's 73GB Raptor (*drool*), and moving from a 133MB/s to 
150MB/s interface makes essentially no difference to performance. SATA 
is nice to work with, but you won't be working on the innards of your 
server much. Perhaps you can afford a little downtime if a drive fails, 
or can arrange to have a hot-spare disk? Unless you're using a real RAID 
controller, you'll probably need downtime after a disk failure anyway.

I needed SATA because I needed SCSI-style hot-swap drives (for 
replacement RAID drives, and for backups), yet needed an ATA-like 
price-per-megabyte (I have to store 3GB/week and rising, keeping it 
readily accessable at all times). PATA raid involved cabling from hell 
(5 drives initially, 8 soon, and probably 16 eventually) and ugly hacks 
for hot-swap, so ATA was the only choice. Unless you share these 
somewhat unusual requirements, perhaps a more basic solution might be in 
order.

A quality RAID controller is worth it's weight in gold - but you pay 
almost it's weight in gold, too. I doubt you'll be able to get one - be 
it for SATA, PATA, or SCSI - unless your budget is larger than it sounds.

One final tip: Maxtor are making yawning gulfs of storage now, otherwise 
known as 300GB 5400RPM disks. Very nice if you need hot archival 
storage, but don't need lots of speed. If I can find them with an SATA 
interface, I plan to pop 3 into our core server and move the archives 
onto them - 600GB of RAID5 storage should keep even us going for a 
little while.

Craig Ringer