Re: background fsck service - any tools?

9 Nov 2012


      Craig Sanders <cas@taz.net.au> writes:
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On Tue, Nov 06, 2012 at 02:05:25PM +1100, Jason White wrote:
...
Andrew Worsley <amworsley@gmail.com> wrote:
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Is there any tool that will unmount a filesystem and fsck say once
every 2-3 months to avoid having the
massive slow fsck on the reboot every 6-12 months?
Use a journalled filesystem.
...
...
I avoid the problem altogether by not using ext2/3/4 as my file system.
That's an integrity check.  You can skip if it you really want to:
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tune2fs -i 0 -c 0 /dev/xxxx
...
...
The Cron job might be your easiest solution.
I tried this, but it whinges constantly about leaking fds, because lvm
is stupid.  I haven't gotten around to cleaning it up.

    $ cat /etc/cron.weekly/avoid-fsck
    #!/bin/bash
    ## e2fsck is usually triggers after enough mounts, or enough time
    ## without a fsck.  For always-on servers, the latter usually means
    ## that after an outage, you have to wait a few hours for the fscks to
    ## finish before normal operation resumes.  This is especially
    ## annoying as it cannot be skipped on Ubuntu 10.04 servers.
    ##
    ## Instead we make an LVM snapshot of each ext LV, and if *that* fscks
    ## OK, we conclude that there were no errors and we set the snapshot's
    ## origin to indicate that a fsck has taken place.

    # Boilerplate prelude ################################################
    set -eEu
    set -o pipefail
    trap 'echo >&2 "$0: unknown error"' ERR
    while getopts d opt
    do case "$opt" in (d) set -x;; ('?') exit 1;; esac
    done
    shift $((${OPTIND:-1}-1))
    # Begin code #########################################################

    # Silently succeed if the necessary tools aren't available, as that
    # strongly indicates this script is not needed on this host.
    { which lvs && which tune2fs; } &>/dev/null || exit 0

    # Output of e2fsck is desirable iff e2fsck had a genuine issue.  It
    # may be arbitrarily long, so a temporary file is more appropriate
    # than a simple bash variable.
    f="`mktemp -t avoid-fsck.XXXXXX`"
    trap 'rm -f "$f"' EXIT

    #lvs | sed 1d | grep '[-o]wi-ao' | # list of LVs (FIXME: dodgy regex).
    lvs --noheadings --separator , --options lv_name,vg_name,origin |
    while IFS="$IFS," read lv vg origin
    do
        # Skip snapshots.
        test -z "$origin" || continue

        # Skip non-ext LVs.
        tune2fs -l "/dev/$vg/$lv" &>/dev/null || continue

        # Cleanup any mess left over from a previous run.
        test ! -e "/dev/$vg/fsck_$lv" ||
        >/dev/null lvremove -f "/dev/$vg/fsck_$lv"

        # NB: 4G should be plenty of space for the COW, since we are only
        # going to keep it around long enough to do a fsck.
        >/dev/null lvcreate --snapshot "/dev/$vg/$lv" --name "fsck_$lv" --size 4G

        if  nice ionice -c3 e2fsck -p "/dev/$vg/fsck_$lv" >"$f" ||
            test $? -eq 1 -o $? -eq 4 -o $? -eq 5 # Ignore "safe" statuses.
        then
            >/dev/null tune2fs -C0 -Tnow "/dev/$vg/$lv"
        else
            >&2 echo "e2fsck -p /dev/$vg/fsck_$lv failed"
            >&2 cat "$f"
        fi
        >/dev/null lvremove -f "/dev/$vg/fsck_$lv"
    done

Re: background fsck service - any tools?

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