PostgreSQL Performance - Re: Best OS & Configuration for Dual Xeon w/4GB &

Author

Re: Best OS & Configuration for Dual Xeon w/4GB &

Luke Lonergan

2006-03-21, 3:34 am

Miguel,

On 3/20/06 1:12 PM, "Miguel" <mmiranda@123.com.sv> wrote:

> i dont know, how can i check?

No matter - it's the benchmark that would tell you, it's probably "access
time" that's being measured even though the text says "seek time". The
difference is that seek time represents only the head motion, where access
time is the whole access including seek. Access times of 4.5ms are typical
of a single 10K RPM SCSI disk drive like the Seagate barracuda.

> I have 6 ultra a320 72G 10k discs

Yah - ouch. With 6 drives in a RAID10, you should expect 3 drives worth of
sequential scan performance, or anywhere from 100MB/s to 180MB/s. You're
getting from half to 1/3 of the performance you'd get with a decent raid
controller.

If you add a simple SCSI adapter like the common LSI U320 adapter to your
DL380G3 and then run software RAID, you will get more than 150MB/s with less
CPU consumption. I'd also expect you'd get down to about 2ms access times.

This might not be easy for you to do, and you might prefer hardware RAID
adapters, but I don't have a recommendation for you there. I'd stay away
from the HP line.

- Luke

---------------------------(end of broadcast)---------------------------
TIP 1: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to majordomo@postgresql
.org so that your
message can get through to the mailing list cleanly

Jim C. Nasby

2006-03-21, 7:28 am

On Mon, Mar 20, 2006 at 01:27:56PM -0800, Luke Lonergan wrote:
>
> Yah - ouch. With 6 drives in a RAID10, you should expect 3 drives worth of
> sequential scan performance, or anywhere from 100MB/s to 180MB/s. You're
> getting from half to 1/3 of the performance you'd get with a decent raid
> controller.
>
> If you add a simple SCSI adapter like the common LSI U320 adapter to your
> DL380G3 and then run software RAID, you will get more than 150MB/s with less
> CPU consumption. I'd also expect you'd get down to about 2ms access times.

FWIW, here's my dirt-simple workstation, with 2 segate SATA drives setup
as a mirror using software (first the mirror, then one of the raw
drives):

decibel@noel.2[5:43]~:15>sudo diskinfo -vt /dev/mirror/gm0
Password:
/dev/mirror/gm0
512 # sectorsize
300069051904 # mediasize in bytes (279G)
586072367 # mediasize in sectors

Seek times:
Full stroke: 250 iter in 1.416409 sec = 5.666 msec
Half stroke: 250 iter in 1.404503 sec = 5.618 msec
Quarter stroke: 500 iter in 2.887344 sec = 5.775 msec
Short forward: 400 iter in 2.101949 sec = 5.255 msec
Short backward: 400 iter in 2.373578 sec = 5.934 msec
Seq outer: 2048 iter in 0.209539 sec = 0.102 msec
Seq inner: 2048 iter in 0.347499 sec = 0.170 msec
Transfer rates:
outside: 102400 kbytes in 3.183924 sec = 32162 kbytes/sec
middle: 102400 kbytes in 3.216232 sec = 31838 kbytes/sec
inside: 102400 kbytes in 4.242779 sec = 24135 kbytes/sec

decibel@noel.2[5:43]~:16>sudo diskinfo -vt /dev/ad4
/dev/ad4
512 # sectorsize
300069052416 # mediasize in bytes (279G)
586072368 # mediasize in sectors
581421 # Cylinders according to firmware.
16 # Heads according to firmware.
63 # Sectors according to firmware.

Seek times:
Full stroke: 250 iter in 5.835744 sec = 23.343 msec
Half stroke: 250 iter in 4.364424 sec = 17.458 msec
Quarter stroke: 500 iter in 6.981597 sec = 13.963 msec
Short forward: 400 iter in 2.157210 sec = 5.393 msec
Short backward: 400 iter in 2.330445 sec = 5.826 msec
Seq outer: 2048 iter in 0.181176 sec = 0.088 msec
Seq inner: 2048 iter in 0.198974 sec = 0.097 msec
Transfer rates:
outside: 102400 kbytes in 1.715810 sec = 59680 kbytes/sec
middle: 102400 kbytes in 1.937027 sec = 52865 kbytes/sec
inside: 102400 kbytes in 3.260515 sec = 31406 kbytes/sec

No, I don't know why the transfer rates for the mirror are 1/2 that as the raw
device. :(
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

Luke Lonergan

2006-03-21, 11:33 am

Jim,

On 3/21/06 3:49 AM, "Jim C. Nasby" <jnasby@pervasive.com> wrote:

> No, I don't know why the transfer rates for the mirror are 1/2 that as the raw
> device. :(

Well - lessee. Would those drives be attached to a Silicon Image (SII) SATA
controller? A Highpoint?

I found in testing about 2 years ago that under Linux (looks like you're
BSD), most SATA controllers other than the Intel PIIX are horribly broken
from a performance standpoint, probably due to bad drivers but I'm not sure.

Now I think whatever is commonly used by Nforce 4 implementations seems to
work ok, but we don't count on them for RAID configurations yet.

- Luke

---------------------------(end of broadcast)---------------------------
TIP 1: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to majordomo@postgresql
.org so that your
message can get through to the mailing list cleanly

Adam Witney

2006-03-21, 11:33 am

> decibel@noel.2[5:43]~:15>sudo diskinfo -vt /dev/mirror/gm0

Can anyone point me to where I can find diskinfo or an equivalent to run on
my debian system, I have been googling for the last hour but can't find it!
I would like to analyse my own disk setup for comparison

Thanks for any help

Adam

--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

Jim C. Nasby

2006-03-21, 1:32 pm

On Tue, Mar 21, 2006 at 07:25:07AM -0800, Luke Lonergan wrote:
> Jim,
>
> On 3/21/06 3:49 AM, "Jim C. Nasby" <jnasby@pervasive.com> wrote:
>
>
> Well - lessee. Would those drives be attached to a Silicon Image (SII) SATA
> controller? A Highpoint?
>
> I found in testing about 2 years ago that under Linux (looks like you're
> BSD), most SATA controllers other than the Intel PIIX are horribly broken
> from a performance standpoint, probably due to bad drivers but I'm not sure.
>
> Now I think whatever is commonly used by Nforce 4 implementations seems to
> work ok, but we don't count on them for RAID configurations yet.

atapci1: <nVidia nForce4 SATA150 controller>

And note that this is using FreeBSD gmirror, not the built-in raid
controller.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461

---------------------------(end of broadcast)---------------------------
TIP 5: don't forget to increase your free space map settings

Mark Kirkwood

2006-03-21, 8:33 pm

Adam Witney wrote:
>
>
>
>
> Can anyone point me to where I can find diskinfo or an equivalent to run on
> my debian system, I have been googling for the last hour but can't find it!
> I would like to analyse my own disk setup for comparison
>

I guess you could use hdparm (-t or -T flags do a simple benchmark).

Though iozone or bonnie++ are probably better.

Cheers

Mark

---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?

http://archives.postgresql.org

Jeff Frost

2006-03-21, 8:33 pm

On Wed, 22 Mar 2006, Mark Kirkwood wrote:

> Adam Witney wrote:
>
> I guess you could use hdparm (-t or -T flags do a simple benchmark).
>
> Though iozone or bonnie++ are probably better.

You might also have a look at lmdd for sequential read/write performance from
the lmbench suite: http://sourceforge.net/projects/lmbench

As numbers from lmdd are seen on this frequently.

--
Jeff Frost, Owner < jeff@frostconsulting
llc.com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

Vivek Khera

2006-03-22, 3:29 am

On Mar 21, 2006, at 12:59 PM, Jim C. Nasby wrote:

> atapci1: <nVidia nForce4 SATA150 controller>
>
> And note that this is using FreeBSD gmirror, not the built-in raid
> controller.

I get similar counter-intuitive slowdown with gmirror SATA disks on
an IBM e326m I'm evaluating. If/when I buy one I'll get the onboard
SCSI RAID instead.

The IBM uses ServerWorks chipset, which shows up to freebsd 6.0 as
"generic ATA" and only does UDMA33 transfers.

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

Sponsored Links