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List:       mysql
Subject:    Re: Best RAID for a DB + LVM?
From:       Aaron Blew <aaronblew () gmail ! com>
Date:       2009-02-24 16:45:45
Message-ID: cdcb615e0902240845g7b0f2446p4f1d84b5a2bfc19e () mail ! gmail ! com
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SCSI/FC/SAS drives are absolutely faster, especially at 15kRPM.  Your
requirement of IOPS vs Usable space may actually make it less expensive to
use FC drives (ex. if you don't have to retain much data but need it to be
really fast _all_ the time).  This can be especially true if you take
datacenter costs into consideration.

There's also a difference between "Enterprise" SATA drives and regular
"Desktop" SATA drives.  The Enterprise class drives tend to be optimized for
workloads that a database may throw at them.

One thing to keep in mind if your dataset isn't terribly large would be to
cram as much RAM in the host as you can.  If you've only got a portion of
your data that's heavily accessed, keeping it in RAM would be ideal.

-Aaron


On Mon, Feb 23, 2009 at 9:17 AM, Brent Baisley <brenttech@gmail.com> wrote:

> SCSI isn't necessarily faster now. The big difference used to be
> SCSI's support for command queueing, which is why it was faster in
> multi-user environments. Command queueing is now fairly common in SATA
> drives.
> The highest end SCSI is probably still faster than the highest end
> SATA, but you will have less disk space and it will cost much more.
> I would recommend using one of the "RAID in a box" solution. They have
> big caches for the whole RAID and they are optimized to the
> controllers. If money isn't really an issue, you may look into
> something like NetApp. That would have everything you need.
>
> Brent Baisley
>
> On Mon, Feb 23, 2009 at 6:58 AM, Andy Smith <a.smith@ukgrid.net> wrote:
> > What RAID level to use, whether to use SCSI or SATA etc are all pretty
> much
> > "how long is a piece of string?" questions. If you have a really high end
> > hardware array RAID 5 may be faster than RAID1+0 is on a cheaper system.
> >
> > Basically
> >
> > RAID 5 = slower
> > SATA = slower
> > RAID 1+0 = faster
> > SCSI = faster
> > more physical disks = faster
> > more expensive controller = faster
> >
> > ;)
> >
> > If you want to compare specific hardware you'll need to get your hands on
> it
> > or find someone else who has already done a comparison. But it will make
> a
> > huge difference to performance what disk array you have hooked up, just
> > depends how much you want to spend....
> >
> > Quoting Waynn Lue <waynnlue@gmail.com>:
> >
> >> I currently have a RAID 5 setup for our database server.  Our space is
> >> running out, so I'm looking to increase the disk space.  Since I'm doing
> >> that anyway, I decided to re-evaluate our current disk array.  I was
> told
> >> that RAID 5 isn't a good choice for databases since it's slower to
> write.
> >> In addition, I've also been considering setting up LVM to take quick db
> >> snapshots, after reading various links on the web (and posts to this
> >> list).
> >>
> >> So on to the questions!  First, if that's what I eventually want to do
> >> (get
> >> a new RAID server with LVM), do I need to do anything special to set up
> >> LVM
> >> on the new system?  Second, what is a good RAID setup for databases?
>  RAID
> >> 10?  0+1?  Third, I have the choice of using SATA or SCSI in conjuction
> >> with
> >> the RAID drives I choose.  How much of a difference is there in using
> SATA
> >> instead of SCSI, especially in light of whatever RAID I end up going
> with?
> >>
> >> Thanks for any insights,
> >> Waynn
> >>
> >
> >
> >
> > --
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> >
> >
>
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>


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