[linux-lvm] Disk crash , LVM and ext2... (bis)
Emmanuel Varagnat
emmanuel.varagnat at free.fr
Tue Oct 1 09:53:48 UTC 2002
Emmanuel Varagnat wrote:
> I played a bit with that, and it looks like when device-mapper can't
> access a zone it returns zeros.
> What I did, is to create an LV over 4 or 5 partitions, format it, zeroed
> the first partition, do a 'vgscan -P' and try to read the block device
> (LV raw data).
> I supposed that this is the device-mapper that hide the missing
> informations by returning zeros. Is there a way to know (via ioctl for
> example) that a data is not available ?
> For my program, I need to know, what is readable and what is not readable.
>
Do you think the LV_BMAP ioctl command could tell me if a block is
available or not into the LV ?
Its purpose is to give the sector number and the drive of a logical
block, isn't it ?
What I want from the LVM is to tell me if data returned by a read
command can be trusted. If it returns me a lot of zeros is it because
the block is not available or because the block effectivly contains zeros.
Thanks a lot.
-=( manu )=-
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