RAID

I am trying to understand file or filegroup placement and RAID.
We have RAID 5 with 5 disks and one primary file group, no secondary.
Trying to keep this thread as simple as possible, just trying to focus on an
understanding of RAID, I sometimes read in publications that it can be
beneficial to place "each file on its own separate physical disk or disk
array".
I want to make sure I understand this statement in light of RAID 5. Does this
mean within RAID 5 I can use one of those 5 disks to place my Transaction Log,
and another one of those 5 disks to place my Primary Data file?
--
Message posted via http://www.sqlmonster.comNo. RAID does not give you access to the individual disks. You access them
as a group. If you can rebuild your RAID array, consider breaking it into a
3-disk RAID5 and a 2-disk RAID1. On the RAID5, put your data. On the
RAID1, put your logs.
If you can get one more disk, then instead of a 3-disk RAID5, go with a
4-disk RAID0+1.
--
Tom
----
Thomas A. Moreau, BSc, PhD, MCSE, MCDBA
SQL Server MVP
Columnist, SQL Server Professional
Toronto, ON Canada
www.pinpub.com
.
"Robert R via SQLMonster.com" <u3288@.uwe> wrote in message
news:5d979be2bd3d1@.uwe...
I am trying to understand file or filegroup placement and RAID.
We have RAID 5 with 5 disks and one primary file group, no secondary.
Trying to keep this thread as simple as possible, just trying to focus on an
understanding of RAID, I sometimes read in publications that it can be
beneficial to place "each file on its own separate physical disk or disk
array".
I want to make sure I understand this statement in light of RAID 5. Does
this
mean within RAID 5 I can use one of those 5 disks to place my Transaction
Log,
and another one of those 5 disks to place my Primary Data file?
--
Message posted via http://www.sqlmonster.com|||So, to confirm my understanding, with my current setup of a 5 disk RAID 5,
even if it is logically partitioned, and the log and data files are on
different partitions on the RAID 5, they [the log and data files] are still
competing against each other. Is that correct?
Tom Moreau wrote:
>No. RAID does not give you access to the individual disks. You access them
>as a group. If you can rebuild your RAID array, consider breaking it into a
>3-disk RAID5 and a 2-disk RAID1. On the RAID5, put your data. On the
>RAID1, put your logs.
>If you can get one more disk, then instead of a 3-disk RAID5, go with a
>4-disk RAID0+1.
>I am trying to understand file or filegroup placement and RAID.
>We have RAID 5 with 5 disks and one primary file group, no secondary.
>Trying to keep this thread as simple as possible, just trying to focus on an
>understanding of RAID, I sometimes read in publications that it can be
>beneficial to place "each file on its own separate physical disk or disk
>array".
>I want to make sure I understand this statement in light of RAID 5. Does
>this
>mean within RAID 5 I can use one of those 5 disks to place my Transaction
>Log,
>and another one of those 5 disks to place my Primary Data file?
>
--
Message posted via http://www.sqlmonster.com|||Correct.
--
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
http://www.solidqualitylearning.com/
Blog: http://solidqualitylearning.com/blogs/tibor/
"cbrichards via SQLMonster.com" <u3288@.uwe> wrote in message news:5d97d9ff865a5@.uwe...
> So, to confirm my understanding, with my current setup of a 5 disk RAID 5,
> even if it is logically partitioned, and the log and data files are on
> different partitions on the RAID 5, they [the log and data files] are still
> competing against each other. Is that correct?
>|||cbrichards via SQLMonster.com wrote:
> So, to confirm my understanding, with my current setup of a 5 disk RAID 5,
> even if it is logically partitioned, and the log and data files are on
> different partitions on the RAID 5, they [the log and data files] are still
> competing against each other. Is that correct?
>
You'll have to see a RAID array just like a single disk - it's just
"build" from a number of physical disks, but act as one. Like already
mentioned, an option would be to reconfigure your RAID into different
arrays using each their own disks. If available it's also advised to
split the RAID arrarys on different controllers - that can also give
some better performance on a busy storage.
Regards
Steen