I always assumed SCSI disks had a write-through cache and therefore
didn't need a drive cache flush comment.
Maximum performance can only be reached with a writeback cache so the
drive can reorder and cluster writes, according to the realtime position
of the heads and platter rotation.
Robert Haas robertmh...@gmail.com writes:
On Thu, Feb 25, 2010 at 7:03 PM, Tom Lane t...@sss.pgh.pa.us wrote:
Partially. There are stats now but autovacuum is not bright about
when to update them.
Is that something you're planning to fix for 9.0? If not, we at least
need to document what
On Thu, Feb 25, 2010 at 6:44 PM, Bruce Momjian br...@momjian.us wrote:
Was this corrected? I don't see any commits to seg.c.
I don't think this was ever reviewed.
It seems like a good patch but I'd be skeptical of committing it now
unless someone has the time to review it carefully. If not,
On Tue, Mar 2, 2010 at 4:23 PM, Tom Lane t...@sss.pgh.pa.us wrote:
Robert Haas robertmh...@gmail.com writes:
On Thu, Feb 25, 2010 at 7:03 PM, Tom Lane t...@sss.pgh.pa.us wrote:
Partially. There are stats now but autovacuum is not bright about
when to update them.
Is that something
Anyone has any experience doing analytics with postgres. In particular if
10K rpm drives are good enough vs using 15K rpm, over 24 drives. Price
difference is $3,000.
Rarely ever have more than 2 or 3 connections to the machine.
So far from what I have seen throughput is more important than
Francisco Reyes wrote:
Anyone has any experience doing analytics with postgres. In particular
if 10K rpm drives are good enough vs using 15K rpm, over 24 drives.
Price difference is $3,000.
Rarely ever have more than 2 or 3 connections to the machine.
So far from what I have seen throughput
Yeb Havinga wrote:
With 24 drives it'll probably be the controller that is the limiting
factor of bandwidth. Our HP SAN controller with 28 15K drives delivers
170MB/s at maximum with raid 0 and about 155MB/s with raid 1+0.
You should be able to clear 1GB/s on sequential reads with 28 15K
Seconded these days even a single 5400rpm SATA drive can muster almost
100MB/sec on a sequential read.
The benefit of 15K rpm drives is seen when you have a lot of small, random
accesses from a working set that is too big to cache the extra
rotational speed translates to an average
On Tue, Mar 2, 2010 at 2:14 PM, da...@lang.hm wrote:
On Tue, 2 Mar 2010, Francisco Reyes wrote:
Anyone has any experience doing analytics with postgres. In particular if
10K rpm drives are good enough vs using 15K rpm, over 24 drives. Price
difference is $3,000.
Rarely ever have more than
Yeb Havinga writes:
With 24 drives it'll probably be the controller that is the limiting
factor of bandwidth.
Going with a 3Ware SAS controller.
Our HP SAN controller with 28 15K drives delivers
170MB/s at maximum with raid 0 and about 155MB/s with raid 1+0.
Already have simmilar
Scott Marlowe writes:
Then the real thing to compare is the speed of the drives for
throughput not rpm.
In a machine, simmilar to what I plan to buy, already in house 24 x 10K rpm
gives me about 400MB/sec while 16 x 15K rpm (2 to 3 year old drives) gives
me about 500MB/sec
--
Sent via
On Tue, Mar 2, 2010 at 1:51 PM, Yeb Havinga yebhavi...@gmail.com wrote:
With 24 drives it'll probably be the controller that is the limiting factor
of bandwidth. Our HP SAN controller with 28 15K drives delivers 170MB/s at
maximum with raid 0 and about 155MB/s with raid 1+0. So I'd go for the
da...@lang.hm writes:
With sequential scans you may be better off with the large SATA drives as
they fit more data per track and so give great sequential read rates.
I lean more towards SAS because of writes.
One common thing we do is create temp tables.. so a typical pass may be:
*
Greg Smith writes:
in a RAID10, given proper read-ahead adjustment. I get over 200MB/s out
of the 3-disk RAID0
Any links/suggested reads on read-ahead adjustment? It will probably be OS
dependant, but any info would be usefull.
--
Sent via pgsql-performance mailing list
On Tue, Mar 2, 2010 at 2:30 PM, Francisco Reyes li...@stringsutils.com wrote:
Scott Marlowe writes:
Then the real thing to compare is the speed of the drives for
throughput not rpm.
In a machine, simmilar to what I plan to buy, already in house 24 x 10K rpm
gives me about 400MB/sec while 16
Greg Smith writes:
in a RAID10, given proper read-ahead adjustment. I get over 200MB/s out
of the 3-disk RAID0 on my home server without even trying hard. Can you
Any links/suggested reading on read-ahead adjustment. I understand this
may be OS specific, but any info would be helpfull.
Scott Marlowe writes:
Have you tried short stroking the drives to see how they compare then?
Or is the reduced primary storage not a valid path here?
No, have not tried it. By the time I got the machine we needed it in
production so could not test anything.
When the 2 new machines come I
On Tue, 2 Mar 2010, Scott Marlowe wrote:
On Tue, Mar 2, 2010 at 2:30 PM, Francisco Reyes li...@stringsutils.com wrote:
Scott Marlowe writes:
Then the real thing to compare is the speed of the drives for
throughput not rpm.
In a machine, simmilar to what I plan to buy, already in house 24 x
da...@lang.hm writes:
what filesystem is being used. There is a thread on the linux-kernel
mailing list right now showing that ext4 seems to top out at ~360MB/sec
while XFS is able to go to 500MB/sec+
EXT3 on Centos 5.4
Plan to try and see if I have time with the new machines to try
On Mon, 1 Mar 2010, Rainer Pruy wrote:
It is a Java app, using jdbc, but through a proprietary persistence
framework. I'm just busy evaluating the effects on the app of
prohibiting prepared statements via jdbc. If this is not worthwhile, I'm
bound to some expensive reorganizations, sigh.
Scott Marlowe writes:
While 16x15k older drives doing 500Meg seems only a little slow, the
24x10k drives getting only 400MB/s seems way slow. I'd expect a
RAID-10 of those to read at somewhere in or just past the gig per
Talked to the vendor. The likely issue is the card. They used a single
Francisco Reyes wrote:
Going with a 3Ware SAS controller.
Already have simmilar machine in house.
With RAID 1+0 Bonne++ reports around 400MB/sec sequential read.
Increase read-ahead and I'd bet you can add 50% to that easy--one area
the 3Ware controllers need serious help, as they admit:
Francisco Reyes wrote:
Anyone has any experience doing analytics with postgres. In particular
if 10K rpm drives are good enough vs using 15K rpm, over 24 drives.
Price difference is $3,000.
Rarely ever have more than 2 or 3 connections to the machine.
So far from what I have seen throughput is
On Tue, Mar 2, 2010 at 4:50 PM, Greg Smith g...@2ndquadrant.com wrote:
If you only have 2 or 3 connections, I can't imagine that the improved seek
times of the 15K drives will be a major driving factor. As already
suggested, 10K drives tend to be larger and can be extremely fast on
sequential
Scott Marlowe wrote:
True, I just looked at the Hitachi 7200 RPM 2TB Ultrastar and it lists
and average throughput of 134 Megabytes/second which is quite good.
Yeah, but have you tracked the reliability of any of the 2TB drives out
there right now? They're terrible. I wouldn't deploy
On Tue, Mar 2, 2010 at 4:57 PM, Greg Smith g...@2ndquadrant.com wrote:
Scott Marlowe wrote:
True, I just looked at the Hitachi 7200 RPM 2TB Ultrastar and it lists
and average throughput of 134 Megabytes/second which is quite good.
Yeah, but have you tracked the reliability of any of the 2TB
Scott Marlowe wrote:
We've had REAL good luck with the WD green and black drives. Out of
about 35 or so drives we've had two failures in the last year, one of
each black and green.
I've been happy with almost all the WD Blue drives around here (have
about a dozen in service for around two
Robert Haas wrote:
On Thu, Feb 25, 2010 at 6:44 PM, Bruce Momjian br...@momjian.us wrote:
Was this corrected? ?I don't see any commits to seg.c.
I don't think this was ever reviewed.
It seems like a good patch but I'd be skeptical of committing it now
unless someone has the time to
On Tue, Mar 2, 2010 at 6:03 PM, Greg Smith g...@2ndquadrant.com wrote:
Scott Marlowe wrote:
We've had REAL good luck with the WD green and black drives. Out of
about 35 or so drives we've had two failures in the last year, one of
each black and green.
I've been happy with almost all the WD
Scott Marlowe wrote:
Time to do the ESD shuffle I think.
Nah, I keep the crazy drive around as an interesting test case. Fun to
see what happens when I connect to a RAID card; very informative about
how thorough the card's investigation of the drive is.
Our 15k5
seagates have been
Greg Smith writes:
http://www.3ware.com/KB/Article.aspx?id=15383 I consider them still a
useful vendor for SATA controllers, but would never buy a SAS solution
from them again until this is resolved.
Who are you using for SAS?
One thing I like about 3ware is their management utility works
On Tue, Mar 2, 2010 at 7:44 PM, Francisco Reyes li...@stringsutils.com wrote:
Greg Smith writes:
http://www.3ware.com/KB/Article.aspx?id=15383 I consider them still a
useful vendor for SATA controllers, but would never buy a SAS solution from
them again until this is resolved.
Who are you
32 matches
Mail list logo
