Re: [gentoo-user] Best filesystem for virtualized gentoo mail server - WAS: vmWare HowTo / best practices

[Jarry]

On 20-Apr-13 17:00, Tanstaafl wrote:

> Another question - are there any caveats as to which filesystem to use
> for a mail server, for virtualized systems? Ir do the same
> issues/questions apply (ie, does the fact that it is virtualized not
> change anything)?

Problem of virtualized filesystem is not that it is virtualized,
but that it is located on datastore with more virtual systems,
all of them competing for the same i/o. *That* is the bottleneck.
If you switch reiser for xfs or btrfs, you might win (or loose)
a few %. If you optimize your esxi-datastore design, you might
win much more than what you have ever dreamed of.

I have 8 VMs (out of them 6 are Gentoo) hosted on ESXi, intended
for various tasks (mail, dns, mysql, web, etc), moderately loaded.
I used hw-raid controller with 2x sata-hdd in raid1 but performance
was quite dissapointing and I experienced all sorts of i/o jams.
Then I switched hdd for ssd (yes I use 2 of them in raid1, even
if this is not generally recommended) and performance rocks now!
I can start now kernel compilation on all 6 VMs at the same time,
with near-zero performance penalty (depending on cpu/vcpu ratio
and number of threads used). Unthinkable with hdd-based datastore.

I would definitely recommend using SSD. Either directly as
datastore for VMs, or at least as EXSi host-cache. There is
also possibility of "hybrid-raid" (1xSSD and 1xHDD in raid1)
on some raid-controllers. Or if your pocket is really deep,
you could grab one of those FusionIO-cards to avoid being
limited by rather slow sata-interface (SSD for PCIe)...

Jarry

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