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rjt
Asked: 2015-03-12 11:21:59 +0800 CST

In a software RAID1, why does tune2fs -c 0 /dev/sda1 not throw an error but change is not seen in tune2fs -l /dev/sda1?

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The Title pretty much says it all.

Turn off mount count fsck seems to succeed:

tune2fs -c 0 /dev/sda1
tune2fs -c 1 /dev/md0

But listing out via

tune2fs -l /dev/sda1 shows mount count is set back to 1 for /dev/sda1 and /dev/md0.

i only want automatic file system checks on the software raid device, not the member drives, but it keeps going back on for the member drives.

software-raid

3 Answers

  1. My member drives and the RAID1 drive all have the same UUID. Will change the member UUIDs via:

    tune2fs -U time /dev/sda1

    but now i have second thoughts because there seems to be conflicting views on whether the member drive UUIDs should equal the RAID UUID?

    # for fs in md1 sda2 sdb2; do tune2fs -l /dev/${fs} | egrep -i '(UUID|Hash Seed)'; done;
    Filesystem UUID: 0de026e2-a1ce-461c-bb3f-c3982b064b4c Directory Hash Seed: 0a5f8be8-965c-48b2-a0c6-3c1cd314a12f Filesystem UUID: 0de026e2-a1ce-461c-bb3f-c3982b064b4c Directory Hash Seed: 0a5f8be8-965c-48b2-a0c6-3c1cd314a12f Filesystem UUID: 0de026e2-a1ce-461c-bb3f-c3982b064b4c Directory Hash Seed: 0a5f8be8-965c-48b2-a0c6-3c1cd314a12f

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  2. Automatic file system checks at boot time are based on the information you have in the fstab.

    This means either you have a problem in the /etc/fstab configuration or if you are using LABEL or UUID you have a problem how those block devices are configured. I suspect it it a problem related to udev, or udev configuration.

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  3. /dev/md0 is a device on top of /dev/sda1 and /dev/sdX1, the member drives of a RAID 1 array. This means that all changes that you make to a filesystem on /dev/md0 will be propagated to both member drives. This is the answer to your question in the title.

    It also means that the filesystem UUID is exactly the same on both /dev/sdX1 and /dev/mdo.

    Once you have set up RAID 1 with member devices, you should not make any changes to the member drives directly (including tune2fs etc.), because that might disturb the RAID operation.

    What is the original problem you are trying to solve here?

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