RELENG_5, snapshots and disk lock time
Dmitry Morozovsky
marck at rinet.ru
Mon Mar 7 07:07:06 PST 2005
Following up to myself
DM> XL> > dumping the snapshot of 140G ufs2 fyle system under contemporary RELENG_5 I
DM> XL> > found that during mksnap_ffs file system is unresponsible even for reading for
DM> XL> > more than 3 minutes (it's on modern SATA disk with 50+ MBps linear transfer).
DM> XL> > Is it normal?
DM> XL>
DM> XL> mksnap_ffs is expected to suspend your write access, but I think 3
DM> XL> minutes is too long for a 140G file system. Would you please send the
DM> XL> dumpfs output of the said file system?
DM>
DM> Well, as I said, it was even for read access. I checked this with the simple
DM> shell script
DM>
DM> #!/bin/sh
DM>
DM> while true; do
DM> sleep 5
DM> date
DM> ls /lh/.snap
DM> done
It seems accessing snapshot directory is blocked for much more time than to
other fs parts. Changing ls line to ``ls /lh'' leads to
Mon Mar 7 18:02:58 MSK 2005
backup home local pgsql ports src
Mon Mar 7 18:03:41 MSK 2005
so file system has been locked for approx 45 seconds. This seems more
reasonable, but still seems a bit too long for me.
Sincerely,
D.Marck [DM5020, MCK-RIPE, DM3-RIPN]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck at rinet.ru ***
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