On Mon, Apr 16, 2012 at 4:16 PM, <bug556...@arcor.de> wrote: > According to the proposed patch I had a thought and 4 proposals to also cover > the case of systems that are not powered on for 24 hours 7 days a week. > (i.e. power saving policy in place)
Looks good, let's see. > 0) Because checking an array is such a long operation, it may be desirable for > checkarray to distinguish --reset and --interrupt options instead of an > amobiguous --cancel, and be able to --resume any previously started check. Added to the new patchset (coming soon). --resume option looks redundant, for now: default action (check) will resume previously started check or start the new one. > Overall, the kernel should correctly stop an attempt for an automatic check > while a > manual check is running. If a manual check is interrupted manually or by > shutting > down, it may be continued manually or by the next automatic check, if > enabled. However, interrupting a an automatic check should not interrupt > manual > checks. The easiest would be to just skip automatic checks if checks > are already running. Let's see. Right now, this (start/stop/interrupt) can be done via kernel interfaces in /sys/block/mdX/md/ by sysadmin... Thus, there is no chance to easy distinguish "manual" and "automatic" checks. It's a good reason to implement things as simple, as possible. > 1) If writing the sync_completed value to sync_min upon --interrupt does > not survive a reboot, checkarray would definitely have to save the value > separately. Otherwise, all it would ever check is always the same small part > at the beginning of the array. ... Just as it do now. And this save/restore can (optionally!) do /etc/init.d/mdadm. Why checkarray? > (Thus, yes, Sergey I'd say it may be a good idea to let --interrupt "dump" > e.g. > "mdX-next_checkarray_block" state files under /var/lib/mdadm/ for all checks > that are still running, and delete any others files to ensure they start > fresh next time. > The --reset option may just delete all state files.) For now, we can save this dump as an option (default: off). But this ugly "database" (and "autocheck-running" file too) shouldn't be introduced "at all cost" in checkarray. It looks as a job for /etc/init.d/mdadm, see above. > 2) Cronjobs defined in /etc/cron.d are never run if the machine is off during > the scheduled times (i.e. currently checkarray is never run). However, this > should be an easy thing to fix, because anacron is in installed by default: Why local admin can't just change cronjobs shedule? > Simply, drop /etc/cron.d/mdadm from the package, and modify the > /etc/cron.daily/mdadm script to run checkarray --cron --idle --all --quiet. Just start array check is NOT enough (with incremental checks). You should also stop it. > If the machine is running 24h, by default cron will run anacron at 07:30 > in the morning (a time the admin may ensure is before office hours). Anacron > then > takes care of cron.daily. If the machine starts up earlier, it cron.daily > runs earlier. > Just letting the machine boot early enough ensures cron.daily tasks are done > in time. > If anacron is uninstalled cron will run cron.daily at 06:25. > > Limiting the time for performing array checks, in addition to using > the --idle switch may be realized by adapting the following: > > 3) Instead of defining a separate cron job that calls checkarray --cancel > later > (which may never happen if machine is shutdown and is not possible using > cron.daily), let checkarray --cron touch say /var/lib/mdadm/autocheck-running > file > and start the checks, if there are currently no (manual) checks running. > Then sleep say for an AUTOCHECK_TIMESLICE duration defined in > /etc/default/mdadm. After the sleep, if the autocheck-running file is still > there, > remove the file and proceed with the --interrupt action for, otherwise exit. 1) Array check will be stopped anyway on shutdown. We just should figure out if we would like to save/restore sync_min/sync_max on shutdown/reboot. 2) It's not a good idea to reinvent cron, IMHO. But we can instead restrict by sync_max the interval of daily checks (my new patch). So, /etc/cron.daily/mdadm will just cancel the previous check and then run the new one. 3) anyway, a real patch from you can tell us much more then a long specification, right? ;) > 4) /etc/init.d/mdadm should call checkarray --interrupt to trigger proper > saving of all states in case the machine is shut down before an > AUTOCHECK_TIMESLICE has ended. Thus, /etc/init.d/mdadm can handle almost all "black magics" stuff for save and restore (default: not do so!) of sync_min/sync_max. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
