New branch 'renewal-history' available with the following commits:
Author: David Teigland <teigland(a)redhat.com>
Date: Wed Mar 9 11:58:21 2016 -0600
sanlock: renewal history
Keep a history of read and write latencies for a lockspace.
The times are measured for io in delta lease renewal
(each delta lease renewal includes one read and one write).
For each successful renewal, a record is saved that includes:
- the timestamp written in the delta lease by the renewal
- the time in milliseconds taken by the delta lease read
- the time in milliseconds taken by the delta lease write
Also counted and recorded are the number io timeouts and
other io errors that occur between successful renewals.
Two consecutive successful renewals would be recorded as:
timestamp=5332 read_ms=482 write_ms=5525 next_timeouts=0 next_errors=0
timestamp=5353 read_ms=99 write_ms=3161 next_timeouts=0 next_errors=0
timestamp is the value written into the delta lease during
read_ms/write_ms are the milliseconds taken for the renewal
next_timeouts are the number of io timeouts that occured
after the renewal recorded on that line and before the next
successful renewal on the following line.
next_errors are the number of io errors (not timeouts) that
occured after renewal recorded on that line and before the
next successful renewal on the following line.
The command 'sanlock client renewal -s lockspace_name' reports
the full history of renewals saved by sanlock, which by default
is 180 records, about 1 hour of history when using a 20 second
renewal interval for a 10 second io timeout.
(A --summary option could be added to calculate and report
averages over a selected period of the history.)
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