Raid Rebuilding

Hi,
We have a Dell 2650 with raid 5 on it one of the disk had disk Failure and
was replaced with new one and the New disk
was rebuilding its raid on it , my question is when we had a disk failure in
it the server was running very slow disk I/O
was very bad ad after replacing the disk even then for abot 8 hrs the server
was runnin the same, is this bcoz of the raid rebuilding on the disk does the
raid rebuilding does hurt the performance of the server
thanksIt looks like you answered your own question. Yes, RAID rebuilding slows
IO. That is one reason the RAID container is marked 'DEGRADED'. You can
adjust how much of its resources the PERC card devotes to rebuilding, but be
aware that lowering the impact will make the rabuild take longer. Read the
PERC card instructions or the Dell OpenManage instructions for exactly how
to adjust the RAID rebuild rate
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"dines" <dines@.discussions.microsoft.com> wrote in message
news:26610ED8-AC00-4AC3-975B-EC44272148DA@.microsoft.com...
> Hi,
> We have a Dell 2650 with raid 5 on it one of the disk had disk Failure and
> was replaced with new one and the New disk
> was rebuilding its raid on it , my question is when we had a disk failure
in
> it the server was running very slow disk I/O
> was very bad ad after replacing the disk even then for abot 8 hrs the
server
> was runnin the same, is this bcoz of the raid rebuilding on the disk does
the
> raid rebuilding does hurt the performance of the server
> thanks|||Thanks For the info on how to adjust perc card but i have another doubt
the rebuilding started at around 12:30 pm and till 8 :30 pm the server was
very slow though the same amount of load was on the server as it usually has
on it but at 8:30 pm the server was breathing free even though the rebuilding
was not yet competed 30% was completed then my question--is there a limit
until which the rebuilding raid hurts ur server performance only for an
intial period or it goes in the same manner until it rebuilds completely.
thanks
"Geoff N. Hiten" wrote:
> It looks like you answered your own question. Yes, RAID rebuilding slows
> IO. That is one reason the RAID container is marked 'DEGRADED'. You can
> adjust how much of its resources the PERC card devotes to rebuilding, but be
> aware that lowering the impact will make the rabuild take longer. Read the
> PERC card instructions or the Dell OpenManage instructions for exactly how
> to adjust the RAID rebuild rate
> --
> Geoff N. Hiten
> Microsoft SQL Server MVP
> Senior Database Administrator
> Careerbuilder.com
> I support the Professional Association for SQL Server
> www.sqlpass.org
> "dines" <dines@.discussions.microsoft.com> wrote in message
> news:26610ED8-AC00-4AC3-975B-EC44272148DA@.microsoft.com...
> > Hi,
> >
> > We have a Dell 2650 with raid 5 on it one of the disk had disk Failure and
> > was replaced with new one and the New disk
> > was rebuilding its raid on it , my question is when we had a disk failure
> in
> > it the server was running very slow disk I/O
> > was very bad ad after replacing the disk even then for abot 8 hrs the
> server
> > was runnin the same, is this bcoz of the raid rebuilding on the disk does
> the
> > raid rebuilding does hurt the performance of the server
> >
> > thanks
>
>|||It depends. Are you sure you were not running a backup or maintenance task
during the overnight hours? Those are very IO intense and will slow a
server down if the IO system is not running as expected. The impact can
also depend on what part of the disks are being rebuilt. Hotspot contention
could have been part of the problem. This is one of many reasons I don't
use RAID-5 on a production system.
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"dines" <dines@.discussions.microsoft.com> wrote in message
news:96F4C225-5BE3-4FE7-8364-76EE8ED3072C@.microsoft.com...
> Thanks For the info on how to adjust perc card but i have another doubt
> the rebuilding started at around 12:30 pm and till 8 :30 pm the server was
> very slow though the same amount of load was on the server as it usually
has
> on it but at 8:30 pm the server was breathing free even though the
rebuilding
> was not yet competed 30% was completed then my question--is there a limit
> until which the rebuilding raid hurts ur server performance only for an
> intial period or it goes in the same manner until it rebuilds completely.
> thanks
>
> "Geoff N. Hiten" wrote:
> > It looks like you answered your own question. Yes, RAID rebuilding
slows
> > IO. That is one reason the RAID container is marked 'DEGRADED'. You
can
> > adjust how much of its resources the PERC card devotes to rebuilding,
but be
> > aware that lowering the impact will make the rabuild take longer. Read
the
> > PERC card instructions or the Dell OpenManage instructions for exactly
how
> > to adjust the RAID rebuild rate
> >
> > --
> > Geoff N. Hiten
> > Microsoft SQL Server MVP
> > Senior Database Administrator
> > Careerbuilder.com
> >
> > I support the Professional Association for SQL Server
> > www.sqlpass.org
> >
> > "dines" <dines@.discussions.microsoft.com> wrote in message
> > news:26610ED8-AC00-4AC3-975B-EC44272148DA@.microsoft.com...
> > > Hi,
> > >
> > > We have a Dell 2650 with raid 5 on it one of the disk had disk Failure
and
> > > was replaced with new one and the New disk
> > > was rebuilding its raid on it , my question is when we had a disk
failure
> > in
> > > it the server was running very slow disk I/O
> > > was very bad ad after replacing the disk even then for abot 8 hrs the
> > server
> > > was runnin the same, is this bcoz of the raid rebuilding on the disk
does
> > the
> > > raid rebuilding does hurt the performance of the server
> > >
> > > thanks
> >
> >
> >