Are blocks that are read from LVM kept in Linux's block cache?

Question

Does Linux keep blocks that are read from an LVM logical volume in the block cache as it does with blocks read from a "regular" block device or is the IO direct?

Also, do the usual buffering semantics apply for writing to a logical volume?

score 3 · Accepted Answer · answered Mar 22 '13 at 18:25

3

LV -> dm or md device -> sdX -> block layer

This is how an IO goes in case of LVM. If you run blktrace or systemtap, it should be clearer.

answered Mar 22 '13 at 18:25

Soham Chakraborty

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Are blocks that are read from LVM kept in Linux's block cache?

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