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Re: advice on raid controller

From: Will LaShell <will(at)lashell(dot)net>
To: pgsql-performance(at)postgresql(dot)org
Cc: rj(at)last(dot)fm
Subject: Re: advice on raid controller
Date: 2003-09-29 17:20:14
Message-ID: 1064856034.10565.15.camel@lyric.ofsloans.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Mon, 2003-09-29 at 06:48, scott.marlowe wrote:
> I've used the megaraid / LSI cards in the past and they were pretty good 
> in terms of reliability, but the last one I used was the 328 model, from 4 
> years ago or so.  that one had a battery backup option for the cache, and 
> could go to 128 Meg.  We tested it with 4/16 and 128 meg ram, and it was 
> about the same with each, but we didn't do heavy parallel testing either.
> 
> Here's the page on the megaraid cards at lsilogic.com:
> 
> http://www.lsilogic.com/products/stor_prod/raid/ultra320products.html
> 
> On Sun, 28 Sep 2003, Matt Clark wrote:
> 
> > As others have mentioned, you really ought to get battery-backed cache if
> > you're doing any volume of writes.  The ability to do safe write-back
> > caching makes an *insane* difference to write performance.
> > 
> > The site you link to also has that for only 15% more money:
> > http://uk.azzurri.com/product/product.cgi?productId=80
> > 
> > No experience with the card(s) I'm afraid.
> > 
> > In general though, U320 will only be faster than U160 for large sequential
> > reads, or when you have silly numbers of disks on a channel (i.e. more than
> > 4/channel).  If you have silly numbers of disks, then RAID5 will probably be
> > better, if you have 4 disks total then RAID1+0 will probably be better.  In
> > between it depends on all sorts of other factors.  Bear in mind though that
> > if you *do* have silly numbers of disks then more channels and more cache
> > will count for more than anything else, so spend the money on that rather
> > than latest-and-greatest performance for a single channel.

Just to add my thoughts,  we use the MegaRaid Elite 1650 in 3 servers
here that drive our core databases.  We paired up the controllers with
the Seagate Cheetah 10k drives,  we could have purchased the X15's which
are Seagate's 15k version, but due to budget constraints and lack of
true performance increase from the 10k to the 15k rpm drives we didn't
opt for them.

I have to say that I've been 100% pleased with the performance and
reliability of the Megaraid controllers. They do everything a good
controller should and they are very easy to manage. The driver is
actively maintained by the guys at LSI and their tech support personnel
are very good as well.

If you want any specific information or have any questions about our
experience or configuration please feel free to contact me.

Sincerely,

Will LaShell



> > HTH
> > 
> > Matt
> > 
> > > -----Original Message-----
> > > From: pgsql-performance-owner(at)postgresql(dot)org
> > > [mailto:pgsql-performance-owner(at)postgresql(dot)org]On Behalf Of Richard
> > > Jones
> > > Sent: 27 September 2003 18:25
> > > To: pgsql-performance(at)postgresql(dot)org
> > > Subject: [PERFORM] advice on raid controller
> > >
> > >
> > > Hi, i'm on the verge of buying a "MegaRAID SCSI 320-2" raid controller.
> > > I need it to build a db server using 4x ultra320 scsi disks
> > > i'm thinking raid 1+0 but will try with raid5 too and compare
> > >
> > > Does anyone have any experience with this model, good or bad i'd like to
> > > know.. thanks :)
> > >
> > > as seen:
> > > http://uk.azzurri.com/product/product.cgi?productId=188
> > >
> > > Regards,
> > > Richard.
> > >
> > > PS: whoever mentioned starting a site with raid controller
> > > reviews, excellent
> > > idea - its hard to find decent info on which card to buy.

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