| Author |
Message |
Mr. Babco
Guest
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 Posted:
Wed Aug 03, 2005 12:59 am Post subject:
Exchange 2003 Database I/O latency |
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Hi all,
I'm currently running a 2 node cluster with shared disks on a SAN. I have
been analyzing the performance of the database disk and think its maxed out.
The MS documentation states that a 20 ms latency between I/O read and write
is poor performance, but I'm having a bit of trouble measuring with perfmon.
It gives me one second increments and the Physical disk I/O read and I/O
write counters don't give me latency. I think its giving me actual I/O's
per second. What is the best way for me to tell if I/O's a maxed out? Help!
thanks,
babco
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Al Mulnick
Guest
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| Posted:
Wed Aug 03, 2005 4:59 pm Post subject:
Re: Exchange 2003 Database I/O latency |
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20ms dely is the max that you strive for. To calculate the performance of
the database drive you really need more to look at several components.
Check out the Troublshooting Exchange Performance document on
http://www.microsoft.com/exchange/library which has a lot of really useful
information about troubleshooting performance in it (oddly enough :)
Drop a note if that still doesn't make sense.
Al
"Mr. Babco" <news@babconet.com> wrote in message
news:r_KdnUsU47QXkm3fRVn-sw@adelphia.com...
| Quote: | Hi all,
I'm currently running a 2 node cluster with shared disks on a SAN. I
have been analyzing the performance of the database disk and think its
maxed out. The MS documentation states that a 20 ms latency between I/O
read and write is poor performance, but I'm having a bit of trouble
measuring with perfmon. It gives me one second increments and the Physical
disk I/O read and I/O write counters don't give me latency. I think its
giving me actual I/O's per second. What is the best way for me to tell if
I/O's a maxed out? Help!
thanks,
babco
|
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| Back to top |
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Rui J.M. Silva [MVP]
Guest
|
| Posted:
Wed Aug 03, 2005 10:58 pm Post subject:
Re: Exchange 2003 Database I/O latency |
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|
The perf. counters you need are:
- Avg. Disk sec/Read
- Avg. Disk sec/Write
Those 2 will give you the latency.
--
Rui JM Silva
MVP Windows Server System - Exchange Server
Blog "subject: exchange", http://msmvps.com/ehlo
"Mr. Babco" <news@babconet.com> wrote in message
news:r_KdnUsU47QXkm3fRVn-sw@adelphia.com...
| Quote: | Hi all,
I'm currently running a 2 node cluster with shared disks on a SAN. I
have been analyzing the performance of the database disk and think its
maxed out. The MS documentation states that a 20 ms latency between I/O
read and write is poor performance, but I'm having a bit of trouble
measuring with perfmon. It gives me one second increments and the Physical
disk I/O read and I/O write counters don't give me latency. I think its
giving me actual I/O's per second. What is the best way for me to tell if
I/O's a maxed out? Help!
thanks,
babco
|
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| Back to top |
|
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Mr. Babco
Guest
|
| Posted:
Fri Aug 05, 2005 6:14 am Post subject:
Re: Exchange 2003 Database I/O latency |
|
|
Thanks, but is it the differnce between these two or the acutal number
loggeed on each equals the delay. I guess I need the computation for this
spelled out for me.
babco
"Rui J.M. Silva [MVP]" <rjms(nospam4me)@oninet.pt> wrote in message
news:eAPu2TFmFHA.1204@TK2MSFTNGP12.phx.gbl...
| Quote: | The perf. counters you need are:
- Avg. Disk sec/Read
- Avg. Disk sec/Write
Those 2 will give you the latency.
--
Rui JM Silva
MVP Windows Server System - Exchange Server
Blog "subject: exchange", http://msmvps.com/ehlo
"Mr. Babco" <news@babconet.com> wrote in message
news:r_KdnUsU47QXkm3fRVn-sw@adelphia.com...
Hi all,
I'm currently running a 2 node cluster with shared disks on a SAN. I
have been analyzing the performance of the database disk and think its
maxed out. The MS documentation states that a 20 ms latency between I/O
read and write is poor performance, but I'm having a bit of trouble
measuring with perfmon. It gives me one second increments and the
Physical disk I/O read and I/O write counters don't give me latency. I
think its giving me actual I/O's per second. What is the best way for me
to tell if I/O's a maxed out? Help!
thanks,
babco
|
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| Back to top |
|
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Rui J.M. Silva [MVP]
Guest
|
| Posted:
Fri Aug 05, 2005 4:59 pm Post subject:
Re: Exchange 2003 Database I/O latency |
|
|
The one you really must monitor is Avg. Disk sec/Write, because the penalty
is in the write operations. Just make sure this counter stays below 40ms.
And make sure you select the counter for the disk where you have your
Exchange database (90% of disk operation are on this disk, assuming the
server is a back-end).
--
Rui JM Silva
MVP Windows Server System - Exchange Server
Blog "subject: exchange", http://msmvps.com/ehlo
"Mr. Babco" <news@babconet.com> wrote in message
news:NOOdnTwOYvMNI2_fRVn-oA@adelphia.com...
| Quote: | Thanks, but is it the differnce between these two or the acutal number
loggeed on each equals the delay. I guess I need the computation for this
spelled out for me.
babco
"Rui J.M. Silva [MVP]" <rjms(nospam4me)@oninet.pt> wrote in message
news:eAPu2TFmFHA.1204@TK2MSFTNGP12.phx.gbl...
The perf. counters you need are:
- Avg. Disk sec/Read
- Avg. Disk sec/Write
Those 2 will give you the latency.
--
Rui JM Silva
MVP Windows Server System - Exchange Server
Blog "subject: exchange", http://msmvps.com/ehlo
"Mr. Babco" <news@babconet.com> wrote in message
news:r_KdnUsU47QXkm3fRVn-sw@adelphia.com...
Hi all,
I'm currently running a 2 node cluster with shared disks on a SAN. I
have been analyzing the performance of the database disk and think its
maxed out. The MS documentation states that a 20 ms latency between I/O
read and write is poor performance, but I'm having a bit of trouble
measuring with perfmon. It gives me one second increments and the
Physical disk I/O read and I/O write counters don't give me latency. I
think its giving me actual I/O's per second. What is the best way for me
to tell if I/O's a maxed out? Help!
thanks,
babco
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