Messages in this thread | | | From | Andrzej Krzysztofowicz <> | Subject | Re: Problem: Bad blocks on IDE disk | Date | Mon, 14 Dec 1998 17:38:06 +0100 (CET) |
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On Mon, 14 Dec 1998, Mark Lord wrote:
> Andrzej Krzysztofowicz wrote: > > > > Hi, > > Recently a few bad sectors appeared on my IDE disk. And I observed > > wrong (in my opinion) behaviour of IDE driver while handling the bad > > sectors: > > > > 1. PIO mode > > when multicount is set to non zero value the IDE driver generates > > an error even if reading of a bad sector is not directly requested, > > but the it is located in the > > <block_requested+1>..<block_requested+multicount_value-1> > > area. > > This is not a driver issue, but rather, a filesystem one.
I'm rather sure that this is a driver problem. I tested it doing dd /dev/hd?? or mke2fs /dev/hd?? as first access to the disk after re-reading partition-table (cache is invalidated then).
> If you don't want the filesystem code to perform > block-device read-ahead, then TURN IT OFF!!
Yes, hdparm -m0 -a0 is a solution.
But I don't think it is the right solution. Notice that I can't turn off the read-ahead for a single filesystem or even single disk. It is per-major-number feature, so it is set for both disks on the channel :(
> ... > > I think the IDE driver *should not* generate an error (eventually a warning) > > when reading of real bad block is *not* directly requested. I hope that > > ide disk reports the number of sectors (on an I/O port) that have been read > > during an IDE command (even if it sets simultaneously one or more error > > flags). > > In DMA mode, there is no way to know where a transfer was aborted.
Maybe it should retry without read-ahead and generate an error when it fails again ?
> In PIO mode, *maybe* we can tell, but it is very difficult to handle > in the way suggested.
*Why* is it difficult ? I think it would be nice to have it in 2.3/2.4 ...
Regards Andrzej -- ======================================================================= Andrzej M. Krzysztofowicz ankry@mif.pg.gda.pl phone (48)(58) 347 14 61 Faculty of Applied Phys. & Math., Technical University of Gdansk
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