Sounds to me, then, like the use of the snapshot/mirror/peer-to-peer copy features of storage devices e.g. Shark, SATABeast, etc. are currently dangerous to use with Linux filesystems. They would need to be able to coordinate their activities with the filesystem lock/unlock components of the kernel to be made safe?
J. Leslie Turriff VM Systems Programmer Central Missouri State University Room 400 Ward Edwards Building Warrensburg MO 64093 660-543-4285 660-580-0523 [EMAIL PROTECTED] >>>[EMAIL PROTECTED] 07/26/06 9:04 am >>> On Wed, Jul 26, 2006 at 02:28:53PM +0200, Carsten Otte wrote: >Very interresting indeed. This pointed me to reading the >lockfs/unlockfs semantics in Linux, and I think I need to withdraw my >statement regarding flashcopy snapshots: because of the fact that >there is no lockfs/unlockfs interaction when doing flashcopy, and >because of dirty pages in the page cache during snapshot, flashcopy >will not generate a consistent snapshot. Therefore, using flashcopy on >an active volume from outside Linux is _not_ suitable for backup purposes. > >The only feasible way to get a consistent snapshot is to use >dm-snapshot from within Linux. This snapshot copy can later on be used >with a backup feature outside Linux. If you use xfs you can also put the filesystem in frozen state from userspace with the xfs_freeze utility. I know of inhouse backup tools at various companies that make use of this feature. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 !DSPAM:32225,44c776f188571486219204! ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
