Re: SQL Server 2000 STD vs RAID performance
From: Paul Cahill (XYZpaul.cahillXYZ_at_blueyonder.co.uk)
Date: 04/02/04
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Date: Fri, 2 Apr 2004 12:14:40 +0100
You should consider that Raid-5 offers relatively poor performance on
writes. I wouldn't recommend it for the log file.
Also consider what the performance will be like if a raid-5 disk fails. The
controller will have to construct the data on the fly from the parity
information.
Will you be able to run in degraded mode?
I always implement Raid 10 where the cost can be justified. The best of both
worlds.
Take care that your controller implements Raid 10 as a stripe of mirrors.
Some Dell Perc controllers implement as a concatenation of mirrors.
Paul Cahill
""Yuan Shao"" <v-yshao@online.microsoft.com> wrote in message
news:y7otNIFGEHA.2224@cpmsftngxa06.phx.gbl...
> Hi Guillaume,
>
> It depends on your requirements. RAID levels 0, 1, and 5 are typically
used
> with SQL Server.
>
> A hardware disk array improves I/O performance because I/O functions, such
> as striping and mirroring, are handled efficiently in firmware.
Conversely,
> an operating system-based RAID offers lower cost but consumes processor
> cycles. When cost is a consideration and redundancy and high performance
> are required, Microsoft Windows? NT? stripe sets with parity or Windows
> 2000 RAID-5 volumes are a good solution.
>
> Data striping (RAID 0) is the RAID configuration with the highest
> performance, but if one disk fails, all the data on the stripe set becomes
> inaccessible. A common installation technique for relational database
> management systems is to configure the database on a RAID 0 drive and then
> place the transaction log on a mirrored drive (RAID 1). You can get the
> best disk I/O performance for the database and maintain data
recoverability
> (assuming you perform regular database backups) through a mirrored
> transaction log.
>
> If data must be quickly recoverable, consider mirroring the transaction
log
> and placing the database on a RAID 5 disk. RAID 5 provides redundancy of
> all data on the array, allowing a single disk to fail and be replaced in
> most cases without system downtime. RAID 5 offers lower performance than
> RAID 0 or RAID 1 but higher reliability and faster recovery.
>
> For more information, please refer to the following article:
> Comparing Different Implementations of RAID Levels
> http://doc.ddart.net/mssql/sql2000/html/optimsql/odp_tun_1_79pv.htm
>
> I am looking forward to hearing from you soon.
>
> Regards,
>
> Michael Shao
> Microsoft Online Partner Support
> Get Secure! - www.microsoft.com/security
> This posting is provided "as is" with no warranties and confers no rights.
>
- Next message: Mat: "how do I determine what tables/views are being accesed"
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- In reply to: Yuan Shao: "RE: SQL Server 2000 STD vs RAID performance"
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