High Log flush Wait Time

Hello,
We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
to an HP EVA 3000.
4 CPU with HyperTh enabled. 8 GB of RAM
Sqlserver 2000 (SP3a) with 180 Gb of DB.
Since 2 weeks, we have slow performance but CPU are not stressed.
We have High Log flush Wait time (>2000 ms) and high latch wait time (800
ms)
Anyone as an idea ?
THX
Message posted via http://www.sqlmonster.com
You probably also have a high disk queue length on the disk(s) where yout
LOG device lives. Make sure yout LOG files are on a RAID 1 or 1+0 device
with no other data files on those disks. This must be a physical disk set,
not just a logical partition of an underlying shared RAID set.
What is happening is that your SQL server cannot write log files to the disk
in a timely manner. SQL will not process a transaction unless the
write-ahead transaction log has the start transaction marker committed to
disk. Thus, your CPUs are stuck waiting on this particular disk function.
Therefore, you make log writes function as fast as possible. Since logs are
written sequentially in relatively small chunks, RAID 1 or1+ 0 is ideal.
RAID 5 will cause performance bottlenecks on log devices.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"John via SQLMonster.com" <forum@.SQLMonster.com> wrote in message
news:61f18ba8c87443539797e121a8dd7f14@.SQLMonster.c om...
> Hello,
> We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
> to an HP EVA 3000.
> 4 CPU with HyperTh enabled. 8 GB of RAM
> Sqlserver 2000 (SP3a) with 180 Gb of DB.
> Since 2 weeks, we have slow performance but CPU are not stressed.
> We have High Log flush Wait time (>2000 ms) and high latch wait time (800
> ms)
> Anyone as an idea ?
> THX
> --
> Message posted via http://www.sqlmonster.com

High Log flush Wait Time

Hello,
We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
to an HP EVA 3000.
4 CPU with HyperTh enabled. 8 GB of RAM
Sqlserver 2000 (SP3a) with 180 Gb of DB.
Since 2 weeks, we have slow performance but CPU are not stressed.
We have High Log flush Wait time (>2000 ms) and high latch wait time (800
ms)
Anyone as an idea ?
THX
--
Message posted via http://www.sqlmonster.comYou probably also have a high disk queue length on the disk(s) where yout
LOG device lives. Make sure yout LOG files are on a RAID 1 or 1+0 device
with no other data files on those disks. This must be a physical disk set,
not just a logical partition of an underlying shared RAID set.
What is happening is that your SQL server cannot write log files to the disk
in a timely manner. SQL will not process a transaction unless the
write-ahead transaction log has the start transaction marker committed to
disk. Thus, your CPUs are stuck waiting on this particular disk function.
Therefore, you make log writes function as fast as possible. Since logs are
written sequentially in relatively small chunks, RAID 1 or1+ 0 is ideal.
RAID 5 will cause performance bottlenecks on log devices.
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"John via SQLMonster.com" <forum@.SQLMonster.com> wrote in message
news:61f18ba8c87443539797e121a8dd7f14@.SQLMonster.com...
> Hello,
> We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
> to an HP EVA 3000.
> 4 CPU with HyperTh enabled. 8 GB of RAM
> Sqlserver 2000 (SP3a) with 180 Gb of DB.
> Since 2 weeks, we have slow performance but CPU are not stressed.
> We have High Log flush Wait time (>2000 ms) and high latch wait time (800
> ms)
> Anyone as an idea ?
> THX
> --
> Message posted via http://www.sqlmonster.com

High Log flush Wait Time

Hello,
We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
to an HP EVA 3000.
4 CPU with HyperTh enabled. 8 GB of RAM
Sqlserver 2000 (SP3a) with 180 Gb of DB.
Since 2 weeks, we have slow performance but CPU are not stressed.
We have High Log flush Wait time (>2000 ms) and high latch wait time (800
ms)
Anyone as an idea ?
THX
Message posted via http://www.droptable.comYou probably also have a high disk queue length on the disk(s) where yout
LOG device lives. Make sure yout LOG files are on a RAID 1 or 1+0 device
with no other data files on those disks. This must be a physical disk set,
not just a logical partition of an underlying shared RAID set.
What is happening is that your SQL server cannot write log files to the disk
in a timely manner. SQL will not process a transaction unless the
write-ahead transaction log has the start transaction marker committed to
disk. Thus, your CPUs are stuck waiting on this particular disk function.
Therefore, you make log writes function as fast as possible. Since logs are
written sequentially in relatively small chunks, RAID 1 or1+ 0 is ideal.
RAID 5 will cause performance bottlenecks on log devices.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"John via droptable.com" <forum@.droptable.com> wrote in message
news:61f18ba8c87443539797e121a8dd7f14@.SQ
droptable.com...
> Hello,
> We have a Cluster in Windows 2000 AS, with HP Proliant DL580 G2 connected
> to an HP EVA 3000.
> 4 CPU with HyperTh enabled. 8 GB of RAM
> Sqlserver 2000 (SP3a) with 180 Gb of DB.
> Since 2 weeks, we have slow performance but CPU are not stressed.
> We have High Log flush Wait time (>2000 ms) and high latch wait time (800
> ms)
> Anyone as an idea ?
> THX
> --
> Message posted via http://www.droptable.comsql

high log flush wait

I am seeing what appears to be file contention in the
form of log flush waits (consistently longer than 1/sec).
Other than separating the .ldf and .mdf on different
physical devices, is there anything that can be done to
minimize this?
TIA,
AJSeparating the devices is precisely what you should do. Your problem
clearly demonstrates why the recommendation exists in the first place.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:423501c49030$78833070$a601280a@.phx.gbl...
> I am seeing what appears to be file contention in the
> form of log flush waits (consistently longer than 1/sec).
> Other than separating the .ldf and .mdf on different
> physical devices, is there anything that can be done to
> minimize this?
> TIA,
> AJ|||Is there really nothing else that can be done?
I have PLANS to separate them, but I have to wait for new
hardware to arrive. In the meantime, performance is
seriously suffering. Any additional suggestions would be
MOST appreciated.
AJ
>--Original Message--
>Separating the devices is precisely what you should do.
Your problem
>clearly demonstrates why the recommendation exists in
the first place.
>--
>Geoff N. Hiten
>Microsoft SQL Server MVP
>Senior Database Administrator
>Careerbuilder.com
>I support the Professional Association for SQL Server
>www.sqlpass.org
>"AJ" <anonymous@.discussions.microsoft.com> wrote in
message
>news:423501c49030$78833070$a601280a@.phx.gbl...
1/sec).[vbcol=seagreen]
>
>.
>|||You can try and see if there are other performance limitations on your
system, but high log flush wait times won't get better without faster
hardware.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:0aa401c4903b$c7b032a0$a401280a@.phx.gbl...[vbcol=seagreen]
> Is there really nothing else that can be done?
> I have PLANS to separate them, but I have to wait for new
> hardware to arrive. In the meantime, performance is
> seriously suffering. Any additional suggestions would be
> MOST appreciated.
> AJ
> Your problem
> the first place.
> message
> 1/sec).

high log flush wait

I am seeing what appears to be file contention in the
form of log flush waits (consistently longer than 1/sec).
Other than separating the .ldf and .mdf on different
physical devices, is there anything that can be done to
minimize this?
TIA,
AJSeparating the devices is precisely what you should do. Your problem
clearly demonstrates why the recommendation exists in the first place.
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:423501c49030$78833070$a601280a@.phx.gbl...
> I am seeing what appears to be file contention in the
> form of log flush waits (consistently longer than 1/sec).
> Other than separating the .ldf and .mdf on different
> physical devices, is there anything that can be done to
> minimize this?
> TIA,
> AJ|||Is there really nothing else that can be done?
I have PLANS to separate them, but I have to wait for new
hardware to arrive. In the meantime, performance is
seriously suffering. Any additional suggestions would be
MOST appreciated.
AJ
>--Original Message--
>Separating the devices is precisely what you should do.
Your problem
>clearly demonstrates why the recommendation exists in
the first place.
>--
>Geoff N. Hiten
>Microsoft SQL Server MVP
>Senior Database Administrator
>Careerbuilder.com
>I support the Professional Association for SQL Server
>www.sqlpass.org
>"AJ" <anonymous@.discussions.microsoft.com> wrote in
message
>news:423501c49030$78833070$a601280a@.phx.gbl...
>> I am seeing what appears to be file contention in the
>> form of log flush waits (consistently longer than
1/sec).
>> Other than separating the .ldf and .mdf on different
>> physical devices, is there anything that can be done to
>> minimize this?
>> TIA,
>> AJ
>
>.
>|||You can try and see if there are other performance limitations on your
system, but high log flush wait times won't get better without faster
hardware.
--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:0aa401c4903b$c7b032a0$a401280a@.phx.gbl...
> Is there really nothing else that can be done?
> I have PLANS to separate them, but I have to wait for new
> hardware to arrive. In the meantime, performance is
> seriously suffering. Any additional suggestions would be
> MOST appreciated.
> AJ
> >--Original Message--
> >Separating the devices is precisely what you should do.
> Your problem
> >clearly demonstrates why the recommendation exists in
> the first place.
> >
> >--
> >Geoff N. Hiten
> >Microsoft SQL Server MVP
> >Senior Database Administrator
> >Careerbuilder.com
> >
> >I support the Professional Association for SQL Server
> >www.sqlpass.org
> >
> >"AJ" <anonymous@.discussions.microsoft.com> wrote in
> message
> >news:423501c49030$78833070$a601280a@.phx.gbl...
> >> I am seeing what appears to be file contention in the
> >> form of log flush waits (consistently longer than
> 1/sec).
> >>
> >> Other than separating the .ldf and .mdf on different
> >> physical devices, is there anything that can be done to
> >> minimize this?
> >>
> >> TIA,
> >> AJ
> >
> >
> >.
> >

high log flush wait

I am seeing what appears to be file contention in the
form of log flush waits (consistently longer than 1/sec).
Other than separating the .ldf and .mdf on different
physical devices, is there anything that can be done to
minimize this?
TIA,
AJ
Separating the devices is precisely what you should do. Your problem
clearly demonstrates why the recommendation exists in the first place.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:423501c49030$78833070$a601280a@.phx.gbl...
> I am seeing what appears to be file contention in the
> form of log flush waits (consistently longer than 1/sec).
> Other than separating the .ldf and .mdf on different
> physical devices, is there anything that can be done to
> minimize this?
> TIA,
> AJ
|||Is there really nothing else that can be done?
I have PLANS to separate them, but I have to wait for new
hardware to arrive. In the meantime, performance is
seriously suffering. Any additional suggestions would be
MOST appreciated.
AJ
>--Original Message--
>Separating the devices is precisely what you should do.
Your problem
>clearly demonstrates why the recommendation exists in
the first place.
>--
>Geoff N. Hiten
>Microsoft SQL Server MVP
>Senior Database Administrator
>Careerbuilder.com
>I support the Professional Association for SQL Server
>www.sqlpass.org
>"AJ" <anonymous@.discussions.microsoft.com> wrote in
message[vbcol=seagreen]
>news:423501c49030$78833070$a601280a@.phx.gbl...
1/sec).
>
>.
>
|||You can try and see if there are other performance limitations on your
system, but high log flush wait times won't get better without faster
hardware.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"AJ" <anonymous@.discussions.microsoft.com> wrote in message
news:0aa401c4903b$c7b032a0$a401280a@.phx.gbl...[vbcol=seagreen]
> Is there really nothing else that can be done?
> I have PLANS to separate them, but I have to wait for new
> hardware to arrive. In the meantime, performance is
> seriously suffering. Any additional suggestions would be
> MOST appreciated.
> AJ
> Your problem
> the first place.
> message
> 1/sec).