Re: Postgres performance on Veritas VxVM

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Greg Smith:
> Flexibility is often expensive from a performance point of view. We
> regularly tell people here that they have to avoid using Linux's LVM for
> similar reasons--while it shouldn't be so slow, it is. Nothing you can
> do about it but use direct disk partitions instead if you need the
> performance to be good.

Okay, that makes sense. What about using plain slices for the WAL, but
using the VM for the data?

For example, we have 14 disks, so I could allocate 2 for the log in
RAID1 (146GB, which is more than enough), then use the remaining 12
under VxVM for the data.

If I understand right, the critical factor is the WAL write speed; the
VM is easily able to keep up with writes to the data files, since those
are mostly asynchronous. Does this seems like a reasonable solution?

(I'll benchmark this configuration anyway, but I'd be interested in any
comments.)

Thanks,
River.
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