On 18-08-16 16:59, Simon Hobson wrote:
> OT, but there seem to be a few people who understand such in-depth stuff here ;-)
>
> I'm in the process of recovering (with ddrescue) files of a failing drive - no backups as "it's only TV" recordings and I can't afford the disk space anyway. It's going better than I expected with most of the files (typically anything between 1G and 4G in size) reading without any errors - retries on the disk, but no actual read errors.
> Tedious because when the drive warms up, it "goes titsup*" (producing lots of DID_BAD_TARGET errors) and I have to unplug it and let it cool down before restarting the recovery process.
>
> But, mounting the source drive read-only doesn't seem to actually mean read-only as I see errors in syslog related to write errors on the disk. After a dig around, I came across "blockdev --setro <device>" which as I read things means the device itself should be set as read-only.
>
> But I still see things like this in syslog (when I unmount the filesystem) :
>> end_request: I/O error, dev sdf, sector 3037143616
>> Buffer I/O error on device sdf5, logical block 352878592
>> lost page write due to I/O error on sdf5
>> JBD2: Error -5 detected when updating journal superblock for sdf5-8.
> Is it me not understanding things, or is it still trying to write to the disk ?
> Or is it just that the filesystem code still tries to write, but fails either because the filesystem is mounted read-only or the device is set read-only ?
>
>
> * Total Inability To Support Usual Performance
>
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Your right, even with the ro flag the mounting pc would try to repair
the filesystem. For more information and the solutions see
http://forensicswiki.org/wiki/Forensic_Live_CD_issues.

Grtz.

Nick