Re: New RAID-5 800GB array, wich fs ? wich stripe block size ?

[Mike Hardy <mhardy@h3c.com>]

That was a tepid review at best! No offense :-)

FWIW - I've got a 1.7TB RAID5 array that handles exactly the files you 
describe (we're probably doing the same thing - networked media server, 
right? With some other stuff on the side). In addition, it also handles 
rsync backups for all the other machines using the --link-dest argument 
and a rotations so it has an unbelievable amount of symlinks in the 
filesystem.

I also have a 1.0TB RAID5 array in a separate machine that I use as a 
backup for the main server, where all the media stuff gets backed up, 
but I don't backup the backups since that would be silly, or overkill at 
least.

I just chose plain vanilla ext3 ('mke2fs -j -m1 /dev/md2') on top of 
plain ol' raid 5. The only option that's different there is the "m1" 
since with an enormous filesystem, reserving 5% of it for root use is a 
bit silly.

With regard to performance, the first thing you'll notice is that unless 
you have gigabit to everywhere, you're limited by network I/O. I am 
anyway. I could saturate a 100Mbit network connection with the read 
speed, and after that, who cares?

Different filesystems will clearly be better for different situations, 
but if you're just looking to serve files over the network you're really 
not going to need to work hard to get it set up "good enough".

I will say though, I've had hardware failures and machine failures take 
the array out before - remember that MTBF is divided by the number of 
parts and arrays usually have lots of parts. Don't forget to backup 
early and often...

-Mike

Bernhard Dobbels wrote:
> 800 GB in one filesystem is possible, but I think it'll make life easier 
> if you have multiple partitions which you can mount wherever you want.
> 
> Technically speaking, I prefer the LVM2 solution on which you can make 
> and resize partitions on the fly.
> 
> I must admit I lost my raid5 with LVM2. The cause will probably have 
> been my fault, although I don't know what I did wrong, so I suggest if 
> you have critical data, a backup on another medium is still advised.
> 
> Good luck.
> 
> Bernhard
> Aurélien Gouny wrote:
> 
>> Hi all,
>>
>> I have a Promise SX6000 card and i juste have bought 6x160 GB HDs that 
>> make a 800 GB RAID-5 array.
>> I was wondering wich filesytem I should use 
>> (ext3/reiserfs/xfs/jfs/...), if I should make one or more partitions 
>> and wich stripe block size to use knowing that:
>>
>> - it will be mainly a file-server with mp3s, divx, pictures (1 to 4MB 
>> each) and some files (openoffice, ...) all shared with Samba.
>> - it will have a small postgresql database
>>
>> If someone need more information in order to determine the stripe 
>> block size or else, just ask ;)
>>
>> Thanks a lot, (sorry for bad english)
>> Aurélien
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