Thread: Re: Easy read-heavy benchmark kicking around?

Select count(*) from table-twice-size-of-ram

Divide the query time by the number of pages in the table times the pagesize (normally 8KB) and you have your net disk
rate.

- Luke

Msg is shrt cuz m on ma treo

 -----Original Message-----
From:     Brian Hurt [mailto:bhurt@janestcapital.com]
Sent:    Monday, November 06, 2006 03:49 PM Eastern Standard Time
To:    pgsql-performance@postgresql.org
Subject:    [PERFORM] Easy read-heavy benchmark kicking around?

I'm having a spot of problem with out storage device vendor.  Read
performance (as measured by both bonnie++ and hdparm -t) is abysmal
(~14Mbyte/sec), and we're trying to get them to fix it.  Unfortunately,
they're using the fact that bonnie++ is an open source benchmark to
weasle out of doing anything- they can't fix it unless I can show an
impact in Postgresql.

So the question is: is there an easy to install and run, read-heavy
benchmark out there that I can wave at them to get them to fix the
problem?  I have a second database running on a single SATA drive, so I
can use that as a comparison point- "look, we're getting 1/3rd the read
speed of a single SATA drive- this sucks!"

Any advice?

Brian


---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster

On 11/8/06, Spiegelberg, Greg <gspiegelberg@cranel.com> wrote:
> Merlin,
>
> I'm kinda shocked you had such a bad exp. with the AMS200.  We have a
> unit here hooked up to a 4-node Linux cluster with 4 databases banging
> on it and we get good, consistent perfomance out of it.  All 4 nodes can
> throw 25 to 75 MB/s simultaneously without a hiccup.
>
> I'm curious, what was your AMS, server and SAN config?

we had quad opteron 870 in a sun v40z.   two trays of 400g sata drives
and the 4 15k fc drives they make you buy.  o/s was originally gentoo
and emulex but we switched to redhat as4/qlogic to get support from
them.

the highest performance we ever got was around 120mb/sec writing to
the 4 fc drives in raid 10.  however, the sata's could not even do 100
and for some reason when we added a second raid group the performance
dropped 40% for a reason that their performance group could not
explain. compounding the problem was that our assigned tech did not
know linux and there was a one week turnaround to get support emails
answered.  Their sales and support staff were snotty and completely
unhelpful.  Also we had to do a complex migration process which
involved physically moving the unit to multiple racks for data
transfer which we were going to have to coordinate with hitachi
support because they do not allow you to rack/unrack your own unit.

ultimately, we returned the unit and bought a adtx san. for less than
half the price of the hitachi, we got a dual 4gb controller mixed
sata/sas that supports 750g sata drives.  It also has sas ports in the
back for direct attachment to sas hba.  in an active/active
configuration, the unit can sustain 500mb/sec, and has 50% more
storage in 1/3 the rack space.

melrin