Validation much slower on virtual platform

[justin_willey]

• SQLA v10.0.1.4051
  
• Win Server 2008 64bit
• DB size 116GB
  
• 32 GB RAM (max cache allocated 29GB)
• 4 x quad core
• Approx 130 users

The resources are all dedicated to the virtual machine.

The previous physical system which had similar RAM (but slower processors). The old system had the data files on a 0+1 RAID array, the new system has (for the moment RAID 5, it will be changed) but significantly faster disks.

Backup of the database takes about 30 mins on both systems.

On the old physical validation took around 4.5 hours, now its taking about 12 hours. The business is seasonal, and user load is low at the moment and general speed of use is fine. While longer validation could be accommodated, the concern is that the much slower performance here may indicate other issues that will become apparent when user load increases again.

I'm not sure where the most likely potential bottlenecks for validation really are - or indeed what statistics to look at the confirm / eliminate them. Any suggestions as to where to start would be much appreciated!

[johnsmirnios]

How many drives are used in the old & new configuration? Validation in v10 can require lots of random IO and the number of spindles would be a limiting factor. FWIW, validation in v12 should be much, much faster.

[justin_willey]

Thanks John - I don't know the answer but I'll find out!

[jeff_albion · Accepted solution]

Is it the actual backup that is taking longer or just the validation? If it's the backup itself, you may be encountering issue CR #676340, fixed in 10.0.1.4258.

If it's just the validation, notably Sybase cannot guarantee the performance of the database server on a virtual machine: http://www.sybase.com/detail?id=1032794#q6

Please note that the extent of support does not cover performance. Sybase does not gurantee the performance for any Sybase products running on virtual machines.

The validation is a combination of CPU and disk activity - I would look at general OS performance counters between the two systems to evaluate how much overhead the virtualization layer is adding.

[Former Member · Accepted solution]

In virtual environments disk IO is often a problem, and validation does a lot of disk IO...

[justin_willey · Accepted solution]

More experimentation suggests that the problem is the speed of connection to the disk array