Re: Disk error only shows up in selftest

RJ> Has anyone come across this before? I have a disk that only shows
RJ> an uncorrectable bad read sector in seltests. Reading and writing
RJ> the same sector via the OS (Ubuntu 13.10) does not produce any
RJ> failures. The outcome of this is that I cannot get the disk to
RJ> reallocate the sector. Just to check my maths I ran a dd to read
RJ> every sector of the disk. This ran without any failures, a self
RJ> test run immediately afterwards showed the same failing sector again!

RJ> Any ideas anyone?

You say you read and _write_, but then say you use dd to *read* the
whole disk...

A read won't force a re-allocation. So, if you really only *read* the
affected sector, it will leave the data there, and not handle a
re-allocation, and thus subsequent reads of that same sector will
fail [unless it's not totally unreadable.]

Writing to it will force a re-allocation, [unless it's able to
successfully write to it.]

So, it sounds like you need to get any data off that sector that you
need, if possible, and then write it. Provided it fails the write, it
should force a re-allocation.

HTH

-Greg


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