Hi,
PostgreSQL 8.1 (and, back then, 7.4) have the tendency to underestimate
the costs of sort operations, compared to index scans.
The Backend allocates gigs of memory (we've set sort_mem to 1 gig), and
then starts spilling out more Gigs of temporary data to the disk. So the
execution gets - in t
On Wed, Nov 22, 2006 at 11:17:23AM +0100, Markus Schaber wrote:
> The Backend allocates gigs of memory (we've set sort_mem to 1 gig), and
> then starts spilling out more Gigs of temporary data to the disk.
How much RAM is in the server? Remember that sort_mem is _per sort_, so if
you have multiple
Dells (at least the 1950 and 2950) come with the Perc5, which is
basically just the LSI MegaRAID. The units I have come with a 256MB BBU,
I'm not sure if it's upgradeable, but it looks like a standard DIMM in
there...
I posted some dd and bonnie++ benchmarks of a 6-disk setup a while back
on a 29
Hi, Steinar,
Steinar H. Gunderson wrote:
> On Wed, Nov 22, 2006 at 11:17:23AM +0100, Markus Schaber wrote:
>> The Backend allocates gigs of memory (we've set sort_mem to 1 gig), and
>> then starts spilling out more Gigs of temporary data to the disk.
>
> How much RAM is in the server? Remember th
On Wed, 22 Nov 2006, Bucky Jordan wrote:
Dells (at least the 1950 and 2950) come with the Perc5, which is
basically just the LSI MegaRAID. The units I have come with a 256MB BBU,
I'm not sure if it's upgradeable, but it looks like a standard DIMM in
there...
I posted some dd and bonnie++ benchm
Hi, Frank,
Frank Wiles wrote:
>> The temporary data is not swapping, it's the Postgres on-disk sort
>> algorithm.
>
>Are you actually running a query where you have a GB of data
>you need to sort? If not I fear you may be causing the system
>to swap by setting it this high.
Yes,
On Wed, 2006-11-22 at 08:36 -0800, Jeff Frost wrote:
> On Wed, 22 Nov 2006, Bucky Jordan wrote:
>
> > Dells (at least the 1950 and 2950) come with the Perc5, which is
> > basically just the LSI MegaRAID. The units I have come with a 256MB BBU,
> > I'm not sure if it's upgradeable, but it looks lik
On Wed, 22 Nov 2006, Joshua D. Drake wrote:
I could only find the 6 disk RAID5 numbers in the archives that were run with
bonnie++1.03. Have you run the RAID10 tests since? Did you settle on 6 disk
RAID5 or 2xRAID1 + 4XRAID10?
Why not 6 drive raid 10? IIRC you need 4 to start RAID 10 but onl
Jeff,
You can find some (Dutch) results here on our website:
http://tweakers.net/reviews/647/5
You'll find the AMCC/3ware 9550SX-12 with up to 12 disks, Areca 1280 and
1160 with up to 14 disks and a Promise and LSI sata-raid controller with
each up to 8 disks. Btw, that Dell Perc5 (sas) is afa
On Wed, 2006-11-22 at 09:02 -0800, Jeff Frost wrote:
> On Wed, 22 Nov 2006, Joshua D. Drake wrote:
>
> >> I could only find the 6 disk RAID5 numbers in the archives that were run
> >> with
> >> bonnie++1.03. Have you run the RAID10 tests since? Did you settle on 6
> >> disk
> >> RAID5 or 2xRAI
On Wed, 22 Nov 2006 15:28:12 +0100
Markus Schaber <[EMAIL PROTECTED]> wrote:
> Hi, Steinar,
>
> Steinar H. Gunderson wrote:
> > On Wed, Nov 22, 2006 at 11:17:23AM +0100, Markus Schaber wrote:
> >> The Backend allocates gigs of memory (we've set sort_mem to 1
> >> gig), and then starts spilling ou
On Wed, 2006-11-22 at 11:02, Jeff Frost wrote:
> On Wed, 22 Nov 2006, Joshua D. Drake wrote:
>
> >> I could only find the 6 disk RAID5 numbers in the archives that were run
> >> with
> >> bonnie++1.03. Have you run the RAID10 tests since? Did you settle on 6
> >> disk
> >> RAID5 or 2xRAID1 + 4
>
> I could only find the 6 disk RAID5 numbers in the archives that were
run
> with
> bonnie++1.03. Have you run the RAID10 tests since? Did you settle on
6
> disk
> RAID5 or 2xRAID1 + 4XRAID10?
>
Unfortunately most of the tests were run with bonnie 1.9 since they were
before I realized that p
Arjen,
As usual, your articles are excellent!
Your results show again that the 3Ware 9550SX is really poor at random I/O
with RAID5 and all of the Arecas are really good. 3Ware/AMCC have designed
the 96xx to do much better for RAID5, but I've not seen results - can you
get a card and test it?
W
I've been trying to optimize a Linux system where benchmarking suggests
large performance differences between the various wal_sync_method options
(with o_sync being the big winner). I started that by using
src/tools/fsync/test_fsync to get an idea what I was dealing with (and to
spot which dri
On Mon, 13 Nov 2006, Guy Thornley wrote:
I've yet to find a drive that lies about write completion. The problem
is that the drives boot-up default is write-caching enabled (or perhaps
the system BIOS sets it that way). If you turn an IDE disks write cache
off explicity, using hdparm or similar
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