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Re: What stripe size for mail server?

On Wed, Nov 10, 2004 at 05:29:37PM -0500, Chris Wagner wrote:
> I would say that RAID 5 is probably overkill for a mail queue.

It's not the mail queue. Its the mail store (maildirs). We have no
problems with mail queue performance so far.

> Unless ur
> mail queue is running hundreds of gigabytes and overloading a single disk,

The store is over 60 GB now, and still growing. Will probably reach over
100 GB in a few months.

> a
> normal single hard drive is sufficient.

Definitely not sufficient for us :)

> Based on ur graph it looks like ur
> queue is under half a gig.

What makes you think so? I did mention that those data were just from a
random sample.

> If you want redundancy for the mail queue then a
> RAID 1 (mirroring) will give u everything u need.

Mirroring seems a little bit to expensive for us. But we will certainly
consider that if someone points me to a comparison that strongly favors
mirroring over RAID5 for a similar setup.

Simply saying that

> RAID 5 is for extremely
> high usage like large file servers and stuff.

is not enough to make the decision, unfortunately.

> Adding RAM to beef up the
> file cache can give u a significant speedup (Ur entire queue can be RAM
> cache).

Unfortunately adding more system RAM to that machine is not an option
(at least for now). We are going to add more RAM to the controller,

> If u still need RAID 5 then I would make the stripe size equal to
> average file size / number of data disks up to no more than 32KB stripe.  

Since avg file size would be something around 2500 bytes, and we have 5
disks, that would give us a 500 byte stripe. I don't think that is even

Marcin Owsiany <porridge@debian.org>             http://marcin.owsiany.pl/
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