[linux-lvm] LVM + Multipath

Ritesh Raj Sarraf rrs at researchut.com
Mon Feb 19 13:03:50 UTC 2007


I have a question regarding the combination of LVM + Multipathing in a SAN

I have a LUN mapped to a host using iSCSI. I have two two paths to the LUN. This
setup, using multipathing, provides me failover functionality.

My question is how does LVM react to path failures ?
In a failover environment, multipathing can take upto 120 seconds to detect that
the active path to the LUN is no more available and then switch to the
secondary path. During this 120 seconds, how does LVM react ? Does it really
sense that the device is offlined ? Or that information is never passed to LVM
and it just allows I/O to happen leaving that responsibility to the
multipathing layer ?

Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."
"Stealing logic from one person is plagiarism, stealing from many is research."
"The great are those who achieve the impossible, the petty are those who
cannot - rrs"

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