diff options
author | martin f. krafft <madduck@debian.org> | 2010-09-02 10:28:23 +0200 |
---|---|---|
committer | martin f. krafft <madduck@debian.org> | 2010-09-02 10:29:51 +0200 |
commit | 27aa15fef8f7e48ac1d91befe407df96fc8fcdc1 (patch) | |
tree | 6609c50eb36b9a60d9de48564c791bbc07ba8248 /debian/README.checkarray | |
parent | 5eed58f0662fc564d3a604bee5d6e429f7907dc6 (diff) |
add a note to README.checkarray about I/O scheduling
Signed-off-by: martin f. krafft <madduck@debian.org>
Diffstat (limited to 'debian/README.checkarray')
-rw-r--r-- | debian/README.checkarray | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/debian/README.checkarray b/debian/README.checkarray index 8cefe016..8071a4d6 100644 --- a/debian/README.checkarray +++ b/debian/README.checkarray @@ -7,6 +7,18 @@ in the morning. This is realised by asking cron to wake up every Sunday with /etc/cron.d/mdadm, but then only running the script when the day of the month is less than or equal to 7. See #380425. +Cron will try to run the check at "idle I/O priority" (see ionice(1)), so that +the check does not overload the system too much. Note that this will only +work if all the component devices of the array employ the (default) "cfq" I/O +scheduler. See the kernel documentation[0] for information on how to verify +and modify the scheduler. checkarray does not verify this for you. + + 0. http://www.kernel.org/doc/Documentation/block/switching-sched.txt + +If you manually invoke checkarray, it runs with default I/O priority. Should +you need to run a check at a higher (or lower) I/O priority, then have a look +at the --idle, --slow, --fast, and --realtime options. + 'check' is a read-only operation, even though the kernel logs may suggest otherwise (e.g. /proc/mdstat and several kernel messages will mention "resync"). Please also see question 21 of the FAQ. @@ -18,4 +30,4 @@ However in the absence of read errors it is read-only. You can cancel a running array check with the -x option to checkarray. - -- martin f. krafft <madduck@debian.org> Mon, 08 Jan 2007 02:07:19 +0100 + -- martin f. krafft <madduck@debian.org> Thu, 02 Sep 2010 10:27:29 +0200 |