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
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 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)
Wi
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
BTW, tnx for the opinion ...
I forgot to cc list ...
Begin forwarded message:
From: Yves Vindevogel <[EMAIL PROTECTED]>
Date: Fri 17 Jun 2005 23:29:32 CEST
To: [EMAIL PROTECTED]
Subject: Re: [PERFORM] Multiple disks: RAID 5 or PG Cluster
Ok, striping is a good option ...
I'll tel
Ok, I will hate that day, but it's only 6 months
Begin forwarded message:
From: Vivek Khera <[EMAIL PROTECTED]>
Date: Fri 17 Jun 2005 23:26:43 CEST
To: Yves Vindevogel <[EMAIL PROTECTED]>
Subject: Re: [PERFORM] Multiple disks: RAID 5 or PG Cluster
On Jun 17, 2005, at 5:24 PM
If you truly do not care about data protection -- either from drive loss or from
sudden power failure, or anything else -- and just want to get the fastest
possible performance, then do RAID 0 (striping). It may be faster to do that
with software RAID on the host than with a special RAID controlle
On Jun 17, 2005, at 3:34 PM, Yves Vindevogel wrote:We are looking to build a new machine for a big PG database. We were wondering if a machine with 5 scsi-disks would perform better if we use a hardware raid 5 controller or if we would go for the clustering in PG. If we cluster in PG, do we have re
Hi,
We are looking to build a new machine for a big PG database.
We were wondering if a machine with 5 scsi-disks would perform better if we use a hardware raid 5 controller or if we would go for the clustering in PG.
If we cluster in PG, do we have redundancy on the data like in a RAID 5 ?
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