Messages in this thread | | | From | "Norman Diamond" <> | Subject | ReiserFS, two oddities | Date | Sun, 26 Oct 2003 16:37:26 +0900 |
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This is tangential to my observations about bad blocks (which the disk's firmware refused to reallocate during reads, writes, and S.M.A.R.T. long self-tests). I have had two odd observations which seem related to ReiserFS on perfectly good blocks.
Here is partial output from fdisk's p command, copied by hand: /dev/hda8 18169578 29431079 5630751 83 Linux The first two numbers are the partition's starting and ending LBA sector numbers. fdisk's u command kindly toggles these between cylinder numbers and LBA sector numbers. The third number is the quantity of 1K Linux blocks in the file system, and does not get toggled by fdisk's u command.
The sector is readable if I ignore partitions: # dd if=/dev/hda of=/dev/null bs=512 skip=29431074 count=1 1+0 records in 1+0 records out but not if I address it from inside the partition: # dd if=/dev/hda8 of=/dev/null bs=512 skip=11261496 count=1 dd: reading `/dev/hda8': Input/output error 0+0 records in 0+0 records out
LBA sector number 29431074 is inside the partition. 18169578 + 11261496 = 29431074, verified several times. 11261496 / 2 = 5630748, verified only twice, but it is within the quantity of 1K Linux blocks that the partition has. Why is the sector unreadable when read from inside the partition?
Let's try a minimal, shouldn't-be-helpful sanity test. # dd if=/dev/hda8 of=/dev/null bs=512 skip=11261495 count=1 1+0 records in 1+0 records out Yup, it succeeded, and doesn't help explain the problem 1 sector later.
The second strange observation is that reiserfsck with no options, applied to a non-mounted partition, seems to write to the partition while replaying journaled transactions. When repeated, the number of replayed transactions is 0, so I think the first execution wrote to the partition. (If the partition had been mounted then of course ordinary operations would get get journaled transactions merged into the file system, but I guarantee that this observation occured on a non-mounted partition.) reiserfsck 3.6.4 starts by saying that it will read-only check consistency, but the fact seems to be read-mostly.
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