Our SAP BASIS team is battling performance issues with our new SAP 46 Production system. Part of the on-going analysis involves looking at disk performance.
Short Synopsis: Using information in the Microsoft SQL Server 2000 Performance Tuning Technical Reference there are some values in performance monitor that appear high indicating a performance bottleneck with disk I/O. Specifically, the Average Disk Sec/read and Average disk sec/write are high which indicates disk latency.
The hardware is as follows:
Server: Compaq DL760 8xP3 700 Xeon, 8GB RAM
OS: Windows 2000 AS with SP2 with the /3GB and /pae switches
SQL: SQL 2000 EE
SAN attached via Connectrix Directors, EMC Symmetrix 8730, using 73Gb physicals sliced into 11.6Gb logicals. This server is using six 7-logical member Meta volumes, down three PowerPath connections.
This is similar to a problem we looked at last year. At the time, the conclusion was that Logical Volume Manager mis-reports counters when lots of disks are involved.
The main problem I have is that I think the numbers are whacked. When I see device busies greater than 100% (in this case, you can find devices that are 20,000% busy), I think the numbers are suspect. Write I/O time is high, too, being well over one second in some cases (as I understand it, this is service time which does not include queue).
Is this a counter problem? A reporting problem?
Any insights would be appreciated.
Short Synopsis: Using information in the Microsoft SQL Server 2000 Performance Tuning Technical Reference there are some values in performance monitor that appear high indicating a performance bottleneck with disk I/O. Specifically, the Average Disk Sec/read and Average disk sec/write are high which indicates disk latency.
The hardware is as follows:
Server: Compaq DL760 8xP3 700 Xeon, 8GB RAM
OS: Windows 2000 AS with SP2 with the /3GB and /pae switches
SQL: SQL 2000 EE
SAN attached via Connectrix Directors, EMC Symmetrix 8730, using 73Gb physicals sliced into 11.6Gb logicals. This server is using six 7-logical member Meta volumes, down three PowerPath connections.
This is similar to a problem we looked at last year. At the time, the conclusion was that Logical Volume Manager mis-reports counters when lots of disks are involved.
The main problem I have is that I think the numbers are whacked. When I see device busies greater than 100% (in this case, you can find devices that are 20,000% busy), I think the numbers are suspect. Write I/O time is high, too, being well over one second in some cases (as I understand it, this is service time which does not include queue).
Is this a counter problem? A reporting problem?
Any insights would be appreciated.