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 )=- _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
