Thread: hardware raid suggestions

hardware raid suggestions

From
Brian Hirt
Date:
I've  been using the adaptec ZCR raid cards in our servers for a while
now, mostly small systems with 3 or 6 disks, and we've been very happy
with them.   However, we're building a new DB machine with 14 U320 15K
SCA drives, and we've run into a performance bottlenkeck with the ZCR
card where it just won't scale well.  Without going into too many
details, we've tested RAID5, RAID10 and RAID50 on pretty much every
array size from 4-14 disks (raid 50 tests used more drives), using JFS,
reiserfs and EXT3.  With every different configuration,  performance
didn't improve after array size became greater than 6 disks..   We used
various benchmarks, including pgbench with scale factors of 10, 100,
1000, 5000 and clients of 10, 15, 30 and 45.  We've done many other
tests and monitoring tools, and we've come to the conclusion that the
ZCR is the problem.

We're looking into getting an Adaptec 2200S or the Megaraid 320 2x
which have better processors, and hopefully better performance.  We
feel that the use of the AIC7930 as the CPU on the ZCR  just doesn't
cut it and a faster raid controller would work better. Does anyone out
there have any experience with these cards with postgresql and linux?
If so, would you be willing to share your experiences and possibly give
a recommendation?

--brian


Re: hardware raid suggestions

From
Josh Berkus
Date:
Brian,

> We're looking into getting an Adaptec 2200S or the Megaraid 320 2x
> which have better processors, and hopefully better performance.  We
> feel that the use of the AIC7930 as the CPU on the ZCR  just doesn't
> cut it and a faster raid controller would work better. Does anyone out
> there have any experience with these cards with postgresql and linux?
> If so, would you be willing to share your experiences and possibly give
> a recommendation?

Yes, my experience with adaptecs has been universally bad.   I just really
don't think that "the SCSI-2 card company" is up to making high-end raid
cards.

MegaRaid is generally positively reviewed in a lot of places.  Be careful to
order the battery back-up at the same time as the Raid card; the batteries
have the annoying habit of going off the market for months at a time.

You should also consider looking into driver issues.   In general, the RAID
card drivers distributed for Linux simply aren't as good as those the same
companies write for Windows or Unix.  That may be your issue with the ZCR, as
well as CPU.

Oh, and don't bother with the upgrade if you're not getting battery backup.
You need it.

--
Josh Berkus
Aglio Database Solutions
San Francisco

Re: hardware raid suggestions

From
Mark Aufflick
Date:
Not sure what your hw platform is, but I always used to get fantastic
performance from Compaq Smart Array battery backed cards. Note that I
haven't bought any recently so HP may have "hp invent"-ed them...

But whatever the brand - if you get a swag of battery backed cache you
won't know yourself. It's fun to install an OS on them as well - watch
the drive format and verify take 10 seconds ;)

Another option to look at is outboard raid boxes that present a single
drive "interface" to the server - I know people  who swear by them.
--
Mark Aufflick
   e  mark@pumptheory.com
   w  www.pumptheory.com (work)
   w  mark.aufflick.com (personal)
   p  +61 438 700 647
On 16/07/2004, at 4:07 AM, Brian Hirt wrote:

> I've  been using the adaptec ZCR raid cards in our servers for a while
> now, mostly small systems with 3 or 6 disks, and we've been very happy
> with them.   However, we're building a new DB machine with 14 U320 15K
> SCA drives, and we've run into a performance bottlenkeck with the ZCR
> card where it just won't scale well.  Without going into too many
> details, we've tested RAID5, RAID10 and RAID50 on pretty much every
> array size from 4-14 disks (raid 50 tests used more drives), using
> JFS, reiserfs and EXT3.  With every different configuration,
> performance didn't improve after array size became greater than 6
> disks..   We used various benchmarks, including pgbench with scale
> factors of 10, 100, 1000, 5000 and clients of 10, 15, 30 and 45.
> We've done many other tests and monitoring tools, and we've come to
> the conclusion that the ZCR is the problem.
>
> We're looking into getting an Adaptec 2200S or the Megaraid 320 2x
> which have better processors, and hopefully better performance.  We
> feel that the use of the AIC7930 as the CPU on the ZCR  just doesn't
> cut it and a faster raid controller would work better. Does anyone out
> there have any experience with these cards with postgresql and linux?
> If so, would you be willing to share your experiences and possibly
> give a recommendation?
>
> --brian
>
>
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Re: hardware raid suggestions

From
"Fred Moyer"
Date:
> We're looking into getting an Adaptec 2200S or the Megaraid 320 2x
> which have better processors, and hopefully better performance.  We
> feel that the use of the AIC7930 as the CPU on the ZCR  just doesn't
> cut it and a faster raid controller would work better. Does anyone out
> there have any experience with these cards with postgresql and linux?
> If so, would you be willing to share your experiences and possibly give
> a recommendation?

I have worked with at least four major name brands of scsi and ide raid
controllers and so far the one I have found to be generally the most
featured and fastest is the ICP Vortex controllers
(http://www.icp-vortex.com/).  It is also more expensive than the others
but has been worth the cost IMHO.  It has a command line utility to
measure disk performance and I believe the source code for it is
available.  I have measured over 200 MB/s reads off these controllers on
3u disk array units.  I'm sure I could have gotten more with additional
tuning.

Fred

Re: hardware raid suggestions

From
Gaetano Mendola
Date:
Brian Hirt wrote:

> I've  been using the adaptec ZCR raid cards in our servers for a while
> now, mostly small systems with 3 or 6 disks, and we've been very happy
> with them.   However, we're building a new DB machine with 14 U320 15K
> SCA drives, and we've run into a performance bottlenkeck with the ZCR
> card where it just won't scale well.  Without going into too many
> details, we've tested RAID5, RAID10 and RAID50 on pretty much every
> array size from 4-14 disks (raid 50 tests used more drives), using JFS,
> reiserfs and EXT3.  With every different configuration,  performance
> didn't improve after array size became greater than 6 disks..   We used
> various benchmarks, including pgbench with scale factors of 10, 100,
> 1000, 5000 and clients of 10, 15, 30 and 45.  We've done many other
> tests and monitoring tools, and we've come to the conclusion that the
> ZCR is the problem.
>
> We're looking into getting an Adaptec 2200S or the Megaraid 320 2x which
> have better processors, and hopefully better performance.  We feel that
> the use of the AIC7930 as the CPU on the ZCR  just doesn't cut it and a
> faster raid controller would work better. Does anyone out there have any
> experience with these cards with postgresql and linux?  If so, would you
> be willing to share your experiences and possibly give a recommendation?
>

Did you consider the option of use an external storage array ?
We are using the dell emc CX600

http://www.dell.com/downloads/emea/products/pvaul/en/Dell_EMC_cx600_specs.pdf

and I'm forgotting to have a disk behind...



Regards
Gaetano Mendola