RDBMS performance characteristics:
- Traditionally CPU and Disk I/O intensive.
- Require adequate amounts of CPU power to prevent SQL scheduler thread queuing.
- Require fast I/O throughput to write logs without affecting query performance.
From a performance perspective, these issues arise:
- CPU contention with other processes and virtual machines.
- Disk I/O contention when writing logs or dealing with write-intensive database activity.
Use uni-processor virtual machines to begin with, upgrading to VSMP virtual machines only if necessary.
- It is easy to move from a UP HAL to a SMP HAL, but not vice-versa.
- Upgrading from UP to SMP mode requires a compulsive HAL change which can result in HLT related issues after the upgrade when using Win2k virtual machines.
- Re-installation is required only when moving between ACPI and non-ACPI configurations. Virtual machines with two VCPUs require two PCPUs to be available to service a request. Systems with few PCPUs or many VSMP.
- Virtual machines may see poor performance.
Adjusting CPU resources from uni-processor to SNP when needed:
- Database performance suffers if CPU resources are constrained.
- Consider increasing minimum and maximum CPU resource allocations to reduce this queue length.
Separate data and logs on different physical disks:
Consider RAID 10 for write intensive databases:
- RAID 10 is more efficient than RAID 5 for writes, but requires more disks.
- Calculate your read/write ratio to determine if your database is write intensive.
- After your database has been running for a few days, run Windows Task Manager and view the total number of I/O Read Bytes and I/O Write Bytes for the sqlservr.exe process.
This shows you the ratio of SQL Server reads to writes since the SQL Server service was last restarted.
Disk provisioning and alignment:
- Configure the vmdks as eagerzeroedthick to avoid overhead I/O for space provisioning.
- Systems prior to Server 2008 may need the partitions aligned for additional performance. See manufacturer for details on this process.
Disable screen savers and unused devices:
- Screen savers and devices like floppy drives, CD-ROM drives, serial ports, etc. consume resources, even when they are not in use.
Summary:
Additional Information
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