Databases Reference
In-Depth Information
SANs and DAS both have their place as storage solutions for SQL Server, and which one you choose will
depend on your budget and the scope of the solution you're designing.
HBA
Fabric
Disk
Array
Figure 6-5
HBA Queue Depth
The queue depth on a HBA is a limit on the number of requests that can be ''in-flight'' on your storage
network and by default will be between 8 and 32. You've already established that SQL Server is I/O
intensive so the default queue depth is usually sub-optimal. A setting of 64 or greater will provide better
results in I/O intensive periods but will make the SAN work harder, which could in turn affect the
performance of other systems that use the SAN.
Best Practice
If no other servers use the SAN, then set the queue depth to 64 or 128 using windows
device manager. If you're concerned about the performance impact on other systems,
then increase the queue depth gradually until you reach an acceptable balance.
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