Re: [exim] SSD Drives

On 2012-07-13 at 16:50 -0500, Matt wrote:
> Anyone using SSD drives to run there entire email server with a
> thousands of accounts? Any issues with cells on the SSD going bad?

No; but I can speak to the issues.

Loosely speaking, a mail-server which is an MTA relay is going to be
heavily I/O bound, with as much writing as reading, while an IMAP server
might be skewed more towards reading.

All but the most recent SSDs are very fast for reading, but slow for
writing. They're not really much better (if at all) suited for
mail-server work than a spinning disk. Some of the dedicated memory
devices would have been better fits.

But now the latest generation of SSDs match read and write speeds and
the reliability is way up. I'd be inclined to look more closely at
them, if you have queues which can grow large and need many
queue-runners to process.

You're looking for *both* read and write speed to be at least 500MB/s,
in the 80k-90k IOPS range, for this to hold.

For the laptop I'm writing this via, I bought one of these from NewEgg:
OCZ Vertex 4 VTX4-25SAT3-256G 2.5" 256GB SATA III MLC Internal Solid
State Drive (SSD)
$300, purchased while it was on offer at $240.

This was based upon discussion and advice from a friend who knows
significantly more than me about memory technologies (he used to work
for a memory manufacturer).

Given the lack of seek time, and the raw speed of these, they're worth
looking at *if* you're hitting an I/O bottleneck; but be aware that
doing so is increasing the size of the failure domain when one machine
goes down, so it's also worth considering if spreading your workload
over more machines is a better solution, just based on what happens when
you lose one or more of them.

-Phil