Messages in this thread | | | Date | Fri, 28 Jan 2005 11:39:58 -0500 | From | Ric Wheeler <> | Subject | Re: raid 1 - automatic 'repair' possible? |
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Having looked at a lot of disks, I think that it is definitely worth forcing a write to try and invoke the remap. With large drives, you usually several bad sectors in the normal case (drive vendors allocate up to a couple thousand spare sectors just for remapping).
Depending on the type of drive error, the act of writing is likely to clean the questionable sector and leave you with a perfectly fine disk.
Ric
Jakob Oestergaard wrote:
>On Wed, Jan 19, 2005 at 11:48:52AM +0100, Kiniger wrote: >... > > >>some random thoughts: >> >>nowadays hardware sector sizes are much bigger than 512 bytes >> >> > >No :) > > > >>and >>the read error may affect some sectors +- the sector which actually >>returned the error. >> >> > >That's right > > > >>to keep the handling in userspace as much as possible: >> >>the real problem is the long resync time. therefore it would >>be sufficient to have a concept of "defective areas" per partition >>and drive (a few of them, perhaps four or so , would be enough) >>which will be excluded from reads/writes and some means to >>re-synchronize these "defective areas" from the good counterparts >>of the other disk. This would avoid having the whole partition being >>marked as defective. >> >> > >I wonder if it's really worth it. > >The original idea has some merit I think - but what you're suggesting >here is almost "bad block remapping" with transparent recovery and user >space policy agents etc. etc. > >If a drive has problems reading the platter, it can usually be corrected >by overwriting the given sector (either the drive can actually overwrite >the sector in place, or it will re-allocate it with severe read >performance penalties following). But there's a reason why that sector >went bad, and you realy want to get the disk replaced. > >I think the current policy of marking the disk as failed when it has >failed is sensible. > >Just my 0.02 Euro > > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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