[Gllug] Fileserver hardware advice

[Mike Brodbelt]

Thomi Richards wrote:

> I plan to have roughly 400GB of free space to start with, but add disks as I 
> need them. I was thinking of using EVMS for that. I want to 'export' this 
> space using both NFS and SMB network protocols to an internal network (only).

Ideally, you should buy a RAID controller that allows you to add disks 
into an array - 3ware or Areca make nice SATA controllers that have 
excellent Linux support, and don't cost an arm and a leg. You can always 
use MD instead if cost is a huge issue - you don't mention whether this 
is a personal project, or for a business. I'd also use LVM, rather than 
EVMS, but that's your call.

> I have a few specific questions:
> 
> 1) I have a few old 200GB PATA disks lieing around that I want to use. What 
> kind of performance can I expect from a PATA disk compared to a SATA one? 

Personally I'd just chuck 'em. Old PATA disks spell data death to me, 
but YMMV.

> Assuming both disks have similar cache sizes, does it hold true that SATA 
> disks are always faster / better than PATA ones?

Not always, but it's not a bad assumption on the whole.

> 1a) Will using a mix of PATA and SATA in an EVMS 'cluster' (or whatever the 
> right EVMS terminology is) degrade performance?

Yes - any kind of array will be limited by the slowest performing 
member. How you arrange the disk layout and topology will be the 
deciding factor.

> 2) Assuming I use NFS to access the files on the share, how much difference 
> will using a 1Gbps network between client and server make, compared to a 
> 100Mbps network? I'm trying to work out if I'll need to buy a 1Gbps network 
> card for my laptop (sounds expensive). I assume that accessing large files 
> over NFS will max out any connection.. is that correct?

Depends on CPU availability, memory, etc, etc. I have a Linksys NSLU2 - 
it'll do about 80Mbps throughput with netcat, as that's where the CPU 
tops out. Of course it's pretty slow, but you get the idea. Do you need 
1Gbps? How many users will you have, what kind of files, etc?

> 3) As I understand it, neither NFS nor SMB do any kind of computationally 
> heavy encryption, so I guess the machine specs realy don't need to be that 
> beefy - can anyone recommend values int he right ballpark for CPU / RAM 
> allocations?

NFS differs heavily between protocol versions, but it's not heavy on the 
CPU. Any moderately fast x86 machine should be able to saturate 100Mbps 
- 1Gbps is a little faster. My NSLU2 will do about 65Mbps over NFS, nad 
that's with a 266Mhz ARM CPU and 32Mb RAM, so it's not exactly taxing.

> 4) Finally, how much difference will having a 64 bit CPU make when it comes to 
> performance?

It'll likely make things marginally slower for the same clock. Pushing 
64-bit pointers around takes a bit more work.

> Can anyone offer me some advice on this topic? It's been a while since I've 
> had cause to build a PC from parts, and I'd like to do it correctly the first 
> time...

Buy decent hardware. Resist the temptation to chuck any old crap in the 
case just because you have it lying around. Avoid like the *plague* 
anything that requires proprietary drivers - I suggest using "make 
menuconfig" to put together your shopping list. If it's not in the 
vanilla kernel tree, don't even bother.

Mike

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