Michael Stone <[EMAIL PROTECTED]> writes:
> it is possible to have a mirror of more than two disks (which would have the
> same read advantage as the striped configuration with the same number of
> disks) but this is rarely seen because it is expensive.
Actually three-way mirrors are quite commo
Hi All,
I have an app that updates a PostgreSQL db in a batch fashion. After
each batch (or several batches), it issues VACUUM and ANALYZE calls on
the updated tables. Now I want to cluster some tables for better
performance. I understand that doing a VACUUM and a CLUSTER on a table
is wasteful
Of course these numbers are not true as soon as you exceed the stripe
size for a read operation, which is often only 128k. Typically a
stripe of mirrors will not read from seperate halves of the mirrors
either, so RAID 10 is only N/2 best case in my experience, Raid 0+1 is
a mirror of stripes and
On 06/01/2005-07:19PM, Mark Stosberg wrote:
>
> - I saw the hardware tip to "Separate the Transaction Log from the
>Database". We have about 60% SELECT statements and 14% UPDATE
>statements. Focusing more on SELECT performance seems more important
>for us.
>
I would think that would
On Sat, Jun 18, 2005 at 06:42:27PM +0200, Yves Vindevogel wrote:
With striping, each file is distributed over several disks, making
the physical write faster because several disks can do the work.
Same for reading, multiple disks return a part of the file.
A mirror behaves almost exactly the
cc ...
Begin forwarded message:
From: Yves Vindevogel <[EMAIL PROTECTED]>
Date: Sat 18 Jun 2005 18:18:53 CEST
To: PFC <[EMAIL PROTECTED]>
Subject: Re: [PERFORM] Multiple disks: RAID 5 or PG Cluster
There's a basic difference between striping (raid 0) and mirroring (raid 1)
With striping, each f
Hi,
At 18:00 18/06/2005, PFC wrote:
I don't know what I'm talking about, but wouldn't mirorring be
faster
than striping for random reads like you often get on a database ? (ie. the
reads can be dispatched to any disk) ? (or course, not for writes, but if
you won't use fsync, random writ
I do not know what clustering would do for you. But striping will
provide a
high level of assurance that each of your hard drives will process
equivalent
amounts of IO operations.
I don't know what I'm talking about, but wouldn't mirorring be faster
than striping for random reads like
