Disk queue length for lVM

Solution Verified - Updated -

Environment

RHEL5

Issue

  • Is there a disk queue length for lVM filesystems?

  • How do I find out what value is set for a disk queue length for lVM filesystems?

Resolution

In RHEL5, the dm-/lvm stack is pre-scheduled which is simply a pass-thru to the underlying block layer (which is post scheduler), so essentially there are no elevator optimizations (rrqm/s & wrqm/s) performed at LVM layer.

In RHEL5 this would be done at the block layer for the PV. The outbound storage queue_depth is typically set by the driver being used and the value is view-able from sysfs via /sys/block/$DEV/device/queue_depth.

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