Does anybody know how much overhead is involved in keeping a snapshot of an active volume (for 24 hours)? I am currently running LVM1 (waiting for snapshots in LVM2/device mapper) and am making a snapshot of my user volumes overnight. These are left available for 24 hours in the hope that users who damage a file will be able to get "yesterday's copy" from the snapshot without us needing to restore from tape. There is obviously some overhead involved, but does anyone know how much? I guess that the worst case situation is when a file is updated for the first time that day (an example might be a recompilation, particularly if the underlying disk is nearly full, so that the blocks released by removing the object files are quickly reused). In this case, the original data blocks must be placed into the snapshot cache and the new data blocks written to disk. Two writes for the price of one. Perennial question - having had a look at the dm-devel and the lvm2 archives, I cannot find any comments about the status of snapshots in the 2.6 kernel. Can anyone enlighten me? Chris Ritson (Computing Officer and School Safety Officer) Rm 618, Claremont Bridge, EMAIL: C.R.Ritson@ncl.ac.uk School of Computing Science, PHONE: +44 191 222 8175 University of Newcastle, FAX : +44 191 222 8232 Newcastle on Tyne, UK NE1 7RU. http://www.cs.ncl.ac.uk/ _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
