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MalleRIM
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PostPosted: Tue Nov 13, 2007 6:37 pm    Post subject: Check filesystems _after_ finishing boot (mount ro before)? Reply with quote

Hi,
I have 750 GB of diskspace with partitions up to 200GB. I already set the number of mounts before a check to 50. But partitions of 100GB or more take ages to be checked. So I thought of a way to get this working differently, I'd like to have your advice to a good solution.
This is what I thought: Partitions which are to be checked are mounted ro on boot (except from any partition with system files like e.g. /, /home, /boot, /usr). After booting (or while booting) these partitions are checked and re-mounted when the check is successfully finished. A notify after logon which provides information about current checks would be useful but this will be the easiest part.
This would be my newbie solution to this problem: turn off the check of any partition which should not be checked on boot and mount it ro. A script looks for the number of mounts after last check, mounts the filesystems which don't have to be checked rw, then checks the filesystems that have been mounted x times and then mounts them rw.
I don't consider this a very professional solution. Is there a better way?

Malle
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neiljw
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PostPosted: Tue Nov 13, 2007 8:06 pm    Post subject: Re: Check filesystems _after_ finishing boot (mount ro befor Reply with quote

MalleRIM wrote:
I don't consider this a very professional solution. Is there a better way?
Malle


Yeh, don't keep re-booting. Why are you doing it? Given the frequency with which fsck needs to run, I don't see a couple of minutes as a big issue.
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PostPosted: Tue Nov 13, 2007 8:14 pm    Post subject: Reply with quote

I also wonder why the FS check can't be interrupted/postponed during boot. It really annoys me when I have to have my box online quickly.

I got no answers at all:

https://forums.gentoo.org/viewtopic-t-579097.html
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PostPosted: Tue Nov 13, 2007 8:59 pm    Post subject: Re: Check filesystems _after_ finishing boot (mount ro befor Reply with quote

MalleRIM wrote:
I don't consider this a very professional solution. Is there a better way?

Which filesystem(s) did you use for the big partitions? This is the primary reason to use a journaled filesystem like JFS, XFS or ext3. Periodic checks of a relatively clean filesystem take seconds, not minutes.

If you used ext2, you can easily convert to ext3 by simply adding the journal, e.g., tune2fs -j /dev/sda3.
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PostPosted: Wed Nov 14, 2007 3:57 pm    Post subject: Re: Check filesystems _after_ finishing boot (mount ro befor Reply with quote

neiljw wrote:
Yeh, don't keep re-booting. Why are you doing it? Given the frequency with which fsck needs to run, I don't see a couple of minutes as a big issue.

normally I boot my system once a day because it normally only runs 1-3 hours. For the answer to the second part im referring to Paapaa's post. Why wait if there is a better way?
@timeBandit: I am using ext3 for all of my partitions ;)
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Section_8
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PostPosted: Wed Nov 14, 2007 4:42 pm    Post subject: Reply with quote

I have a home PC that boots (more or less) daily and have ext3 on most partitions. The partitions set up so they never do the forced fsck at bootup.

About once a month, I boot a liveCD and do a full system backup. From that backup script, I do the forced fsck of all my partitions.
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MalleRIM
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PostPosted: Tue Nov 20, 2007 9:04 pm    Post subject: Reply with quote

I think this is what I am going to do, but I need a little help because I'm not best at scripting.
I'm going to set the partitions I want to be checked after boot to not being checked. A script checks the number of mounts, and remounts the partitions to be checked ro, checks them and again, remounts them rw. This should be the best solution.
How can I check the number of mounts/time passed since last checking of a filesystem?
How can I remount a filesystem?
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PostPosted: Tue Nov 20, 2007 10:26 pm    Post subject: Reply with quote

MalleRIM wrote:
I think this is what I am going to do, but I need a little help because I'm not best at scripting.
I'm going to set the partitions I want to be checked after boot to not being checked. A script checks the number of mounts, and remounts the partitions to be checked ro, checks them and again, remounts them rw. This should be the best solution.
How can I check the number of mounts/time passed since last checking of a filesystem?
How can I remount a filesystem?


Checking the number of mounts can be done by "tune2fs -l /dev/sdb7". I don't know of a similar tool for reiser/xfs/jfs/whatever.
Remounting: "mount /dev/sdb7 -o ro,remount" will remount the partition ro. Same goes for rw.
However, it would be best for you to set them as "ro" in your fstab and let the script remount them rw when it has checked them. It's quite a risk to mount an unclean FS rw.
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MalleRIM
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PostPosted: Wed Nov 21, 2007 6:01 pm    Post subject: Reply with quote

Quote:
It's quite a risk to mount an unclean FS rw

My script is just to get rid of the routine check during boot. I think I'll leave the check in the fstab and set the script to check the partitions five mounts/days before they have to be checked (in case the fs was remounted manually/not switched on for more than one day) after reaching number of mounts/days to be checked.
reiserfs/xfs/jfs won't be a problem - I'm only using ext3.
I'm not actually familiar with sed. I want to use grep to extract the line wich shows the mounts/days and then use sed to just have the number in a variable. Furthermore I need to know how to write "if $MOUNT_COUNT higher than '45'". I only know == and !=.
edit: I finally figured out, how to cut with sed. Is there a better way than using:
tune2fs -l /dev/sda5 | grep "Mount count" | sed s/"Mount count: "//
there are many spaces which is kind of bugging me... (spaces can't be displayed in the post)
it would also be nice to have a config file in which you can put all the filesystems you want to be checked this way including the number of mounts after which they should be checked. But I have actually no idea how to include a config file in a script.
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MalleRIM
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PostPosted: Thu Nov 22, 2007 11:00 pm    Post subject: Reply with quote

No suggestions?
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MalleRIM
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PostPosted: Mon Nov 26, 2007 8:36 pm    Post subject: Reply with quote

No idea at all?
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PostPosted: Mon Nov 26, 2007 10:33 pm    Post subject: Reply with quote

Yep, there is another, cleaner way: use awk. I don't remember the syntax from the last time I used it, but in your case it should be something along the lines of
Code:
MOUNTS=$(tune2fs /dev/sdb5 -l | grep 'Mount count:' | awk -F: '{ print $3 }')    # For the second ':' separated field

if [ "$MOUNTS" - gt 45 ]
    then DO_WHATEVER
    else DO_SOMETHING_ELSE
fi

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PostPosted: Tue Nov 27, 2007 6:42 am    Post subject: Reply with quote

you might wanna look into suspend2 and hibernation instead of rebooting ;)
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PostPosted: Tue Nov 27, 2007 9:40 pm    Post subject: Reply with quote

The spaces are not even saved in the variable - they are just displayed in the normal output. awk didn't work so I used sed again.
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PostPosted: Tue Nov 27, 2007 11:21 pm    Post subject: Reply with quote

Oops, sorry. Two errors in such a short snippet of code.
First: awk needs "print $2" instead of "print $3" because you want the part after ":", that is, the second colon-separated field. The spaces are ignored, you'll just get the right number (I've checked this time). The $3 was there because I was using space-separated fields before and then I thought about the colons.
Second: the "if" line must have "-gt", not "- gt". That space has no place there.
That should work, or at least it does in my system.
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PostPosted: Wed Nov 28, 2007 4:13 pm    Post subject: Reply with quote

This is my first try:
Code:
FILESYSTEM=$@
COUNT=10
MOUNTS=`tune2fs -l ${FILESYSTEM} | grep "Mount count" | sed s/"Mount count: "//`

if [ "$MOUNTS" -gt ${COUNT} ]
    then
     echo "${FILESYSTEM} has been mounted more than ${COUNT} times, check forced"
     mount -o ro,remount ${FILESYSTEM}
      if [ "$?" != "0" ]
       then
       echo "${FILESYSTEM} can't be mounted ro. Terminate all processes writing ${FILESYSTEM} and try again"
       exit
      fi
     fsck -fyc ${FILESYSTEM}
     mount -o rw,remount ${FILESYSTEM}
     echo "${FILESYSTEM} has been checked"
    else
     echo "${FILESYSTEM} does not have to be checked"
fi
exit 0

It still warns me about a mounted filesystem. can this be ignored?
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MalleRIM
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PostPosted: Mon Dec 03, 2007 7:25 pm    Post subject: Reply with quote

Does anyone know something about this?
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PostPosted: Mon Dec 03, 2007 8:03 pm    Post subject: Reply with quote

my suggestion is that you don't bother mounting the partition till after you finish booting, then deal with fsck in local.start.

The reason why fsck is done at boot is that there's a potential for corruption specifically for the root partition, which is mitigated by rebooting the machine. If you fsck it a read-only mounted disk, the disk potentially could end up with changes from the write portion of fsck to clean up inconsistencies. Now the disk may be clean of inconsistencies but now your RAM cache could be inconsistent with the disk, and you could be hosed remounting that partition read-write.

Leave it unmounted, or unmount it totally before checking.
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PostPosted: Tue Dec 04, 2007 9:37 pm    Post subject: Reply with quote

ok, thanks for the answer ;)
I'll try that when I got time.
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