I have separate drives each SQL Server database:
database file (E:)
database transaction log (K:)
tempdb (M:)
database system files (F:)
My database % Disk Time: (Average = 2541, STDEV = 4316,
Maximum = 86770)
How is the % Disk Time measured?
The % Disk Time high at 55%?
Thanks,
___________________________________________________________
Brian
First of all i have said 'probably'
Secondly if you have this counter higher than 55% for
continuous periods
(let me say 15 min)then your SQL Server
may be experiencing an I/O bottleneck.
"Brian Moran" <brian@.solidqualitylearning.com> wrote in
message
news:%23r7TWIieEHA.2848@.TK2MSFTNGP10.phx.gbl...
> I don't tend to agree with that advice.
>
> On it's own
> <<
> '%Disk Time
> >>
>
> Is not a very reliable indicator of an IO bottleneck.
You could easily
have
> a bottleneck if this counter is much lower than 55%. You
might NOT have a
> bottleneck if this counter is 55% or higher.
>
> There are many, many more counters which you should take
a look. You need
to
> take a look at queue lenght, wait times for disk
transfers, time it takes
> per read and write. In addition, there are a host of
other counters
> specific to your SAN that you should take a look at.
>
>
> Unfortunately, I'm running a bit late right now and I
don't have time to
> write a long message. Tom Davidson from MS has a nice
article in SQL
Server
> Magazine that dicusses some of these counters. I believe
it might also be
on
> MSDN. It shouldn't be too hard to track down if you
search by his name on
> each site.
> --
>
> Brian Moran
>
> "Uri Dimant" <urid@.iscar.co.il> wrote in message
> news:u1rJ0yheEHA.3520@.TK2MSFTNGP10.phx.gbl...
> > Mike
> > This counter measured how busy a physical array is. In
general it should
> be
> > less 55% otherwise you probably jave IO bottleneck.
> >
> >
> >
I have a Windows 2000 Advanced Server with SQL Server 2000
Enterprise Edition on a SAN. What units are the %Disk
Time measured in from Perfmon?
Is the (% Disk Time E) = (Disk Time E) / (Total % Disk
Time) ?
Please help me with these questions.
Thanks,
Mike%Disk time is a bogus number and is useless for performance measurement. It
does not take into account asychronous I/O requests and cannot tell what the
real performance capability of an underlying RAID set may be. I prefer
using Transfers/sec, Read Bytes/sec and Write Bytes/sec, and Disk Queue
length to measure the performance of my disk subsystems. It is important
to take a few hours and benchmark your system with an I/O stress tool before
going live so you will know what your maximum capacities really are.
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"Mike" <anonymous@.discussions.microsoft.com> wrote in message
news:192c01c47bea$40735340$a601280a@.phx.gbl...
> I have separate drives each SQL Server database:
> database file (E:)
> database transaction log (K:)
> tempdb (M:)
> database system files (F:)
> My database % Disk Time: (Average = 2541, STDEV = 4316,
> Maximum = 86770)
> How is the % Disk Time measured?
> The % Disk Time high at 55%?
> Thanks,
> ___________________________________________________________
> Brian
> First of all i have said 'probably'
> Secondly if you have this counter higher than 55% for
> continuous periods
> (let me say 15 min)then your SQL Server
>
> may be experiencing an I/O bottleneck.
> "Brian Moran" <brian@.solidqualitylearning.com> wrote in
> message
> news:%23r7TWIieEHA.2848@.TK2MSFTNGP10.phx.gbl...
> > I don't tend to agree with that advice.
> >
> > On it's own
> > <<
> > '%Disk Time
> > >>
> >
> > Is not a very reliable indicator of an IO bottleneck.
> You could easily
> have
> > a bottleneck if this counter is much lower than 55%. You
> might NOT have a
> > bottleneck if this counter is 55% or higher.
> >
> > There are many, many more counters which you should take
> a look. You need
> to
> > take a look at queue lenght, wait times for disk
> transfers, time it takes
> > per read and write. In addition, there are a host of
> other counters
> > specific to your SAN that you should take a look at.
> >
> >
> > Unfortunately, I'm running a bit late right now and I
> don't have time to
> > write a long message. Tom Davidson from MS has a nice
> article in SQL
> Server
> > Magazine that dicusses some of these counters. I believe
> it might also be
> on
> > MSDN. It shouldn't be too hard to track down if you
> search by his name on
> > each site.
> > --
> >
> > Brian Moran
> >
> > "Uri Dimant" <urid@.iscar.co.il> wrote in message
> > news:u1rJ0yheEHA.3520@.TK2MSFTNGP10.phx.gbl...
> > > Mike
> > > This counter measured how busy a physical array is. In
> general it should
> > be
> > > less 55% otherwise you probably jave IO bottleneck.
> > >
> > >
> > >
> I have a Windows 2000 Advanced Server with SQL Server 2000
> Enterprise Edition on a SAN. What units are the %Disk
> Time measured in from Perfmon?
> Is the (% Disk Time E) = (Disk Time E) / (Total % Disk
> Time) ?
> Please help me with these questions.
> Thanks,
> Mike
>|||That counter is pretty much useless in my opinion. I have seen this vary
greatly with the different types of hardware used. It's better to use the
Avg and current Disk queues instead. They give a much better view of how
your drives are able to handle the load. By the way are these drives
Logical or Physical?
--
Andrew J. Kelly SQL MVP
"Mike" <anonymous@.discussions.microsoft.com> wrote in message
news:192c01c47bea$40735340$a601280a@.phx.gbl...
> I have separate drives each SQL Server database:
> database file (E:)
> database transaction log (K:)
> tempdb (M:)
> database system files (F:)
> My database % Disk Time: (Average = 2541, STDEV = 4316,
> Maximum = 86770)
> How is the % Disk Time measured?
> The % Disk Time high at 55%?
> Thanks,
> ___________________________________________________________
> Brian
> First of all i have said 'probably'
> Secondly if you have this counter higher than 55% for
> continuous periods
> (let me say 15 min)then your SQL Server
>
> may be experiencing an I/O bottleneck.
> "Brian Moran" <brian@.solidqualitylearning.com> wrote in
> message
> news:%23r7TWIieEHA.2848@.TK2MSFTNGP10.phx.gbl...
> > I don't tend to agree with that advice.
> >
> > On it's own
> > <<
> > '%Disk Time
> > >>
> >
> > Is not a very reliable indicator of an IO bottleneck.
> You could easily
> have
> > a bottleneck if this counter is much lower than 55%. You
> might NOT have a
> > bottleneck if this counter is 55% or higher.
> >
> > There are many, many more counters which you should take
> a look. You need
> to
> > take a look at queue lenght, wait times for disk
> transfers, time it takes
> > per read and write. In addition, there are a host of
> other counters
> > specific to your SAN that you should take a look at.
> >
> >
> > Unfortunately, I'm running a bit late right now and I
> don't have time to
> > write a long message. Tom Davidson from MS has a nice
> article in SQL
> Server
> > Magazine that dicusses some of these counters. I believe
> it might also be
> on
> > MSDN. It shouldn't be too hard to track down if you
> search by his name on
> > each site.
> > --
> >
> > Brian Moran
> >
> > "Uri Dimant" <urid@.iscar.co.il> wrote in message
> > news:u1rJ0yheEHA.3520@.TK2MSFTNGP10.phx.gbl...
> > > Mike
> > > This counter measured how busy a physical array is. In
> general it should
> > be
> > > less 55% otherwise you probably jave IO bottleneck.
> > >
> > >
> > >
> I have a Windows 2000 Advanced Server with SQL Server 2000
> Enterprise Edition on a SAN. What units are the %Disk
> Time measured in from Perfmon?
> Is the (% Disk Time E) = (Disk Time E) / (Total % Disk
> Time) ?
> Please help me with these questions.
> Thanks,
> Mike
>|||I mostly use Average disk queue length... Any average disk queue length > 2
on a single spindle = bad.
--
Wayne Snyder, MCDBA, SQL Server MVP
Mariner, Charlotte, NC
www.mariner-usa.com
(Please respond only to the newsgroups.)
I support the Professional Association of SQL Server (PASS) and it's
community of SQL Server professionals.
www.sqlpass.org
"Mike" <anonymous@.discussions.microsoft.com> wrote in message
news:192c01c47bea$40735340$a601280a@.phx.gbl...
> I have separate drives each SQL Server database:
> database file (E:)
> database transaction log (K:)
> tempdb (M:)
> database system files (F:)
> My database % Disk Time: (Average = 2541, STDEV = 4316,
> Maximum = 86770)
> How is the % Disk Time measured?
> The % Disk Time high at 55%?
> Thanks,
> ___________________________________________________________
> Brian
> First of all i have said 'probably'
> Secondly if you have this counter higher than 55% for
> continuous periods
> (let me say 15 min)then your SQL Server
>
> may be experiencing an I/O bottleneck.
> "Brian Moran" <brian@.solidqualitylearning.com> wrote in
> message
> news:%23r7TWIieEHA.2848@.TK2MSFTNGP10.phx.gbl...
> > I don't tend to agree with that advice.
> >
> > On it's own
> > <<
> > '%Disk Time
> > >>
> >
> > Is not a very reliable indicator of an IO bottleneck.
> You could easily
> have
> > a bottleneck if this counter is much lower than 55%. You
> might NOT have a
> > bottleneck if this counter is 55% or higher.
> >
> > There are many, many more counters which you should take
> a look. You need
> to
> > take a look at queue lenght, wait times for disk
> transfers, time it takes
> > per read and write. In addition, there are a host of
> other counters
> > specific to your SAN that you should take a look at.
> >
> >
> > Unfortunately, I'm running a bit late right now and I
> don't have time to
> > write a long message. Tom Davidson from MS has a nice
> article in SQL
> Server
> > Magazine that dicusses some of these counters. I believe
> it might also be
> on
> > MSDN. It shouldn't be too hard to track down if you
> search by his name on
> > each site.
> > --
> >
> > Brian Moran
> >
> > "Uri Dimant" <urid@.iscar.co.il> wrote in message
> > news:u1rJ0yheEHA.3520@.TK2MSFTNGP10.phx.gbl...
> > > Mike
> > > This counter measured how busy a physical array is. In
> general it should
> > be
> > > less 55% otherwise you probably jave IO bottleneck.
> > >
> > >
> > >
> I have a Windows 2000 Advanced Server with SQL Server 2000
> Enterprise Edition on a SAN. What units are the %Disk
> Time measured in from Perfmon?
> Is the (% Disk Time E) = (Disk Time E) / (Total % Disk
> Time) ?
> Please help me with these questions.
> Thanks,
> Mike
>
