On Friday 07 August 2015 19:18:02 Russell Coker wrote: > On Fri, 7 Aug 2015 06:49:58 PM Robert Krig wrote: > > What exactly is contained in btrfs metadata? > > Much the same as in metadata for every other filesystem. > > > I've read about some users setting up their btrfs volumes as > > data=single, but metadata=raid1 > > > > Is there any actual benefit to that? I mean, if you keep your data as > > single, but have multiple copies of metadata, does that still allow you > > to recover from data corruption? Or is metadata redundancy a benefit to > > ensure that your btrfs volume remains mountable/readable? > > If you have redundant metadata and experience corruption then you will know > the name of every file that has data corruption, this is really good for > restoring from backup. Also you will be protected against corruption of a > root directory causing massive data loss. > > If you have the bad luck to have certain metadata structures corrupted with > no redundancy then you can face massive data loss and possibly have the > entire filesystem become at least temporarily unusable. While corruption > of the root directory is unlikely it is possible. With "dup" metadata I've > seen a BTRFS filesystem remain usable after 12,000+ read errors.
While we're at it: any idea why the default for SSD's is single for meta data as described on the wiki? (https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices#Filesystem_creation) I was looking for an answer why my SSD just had single metadata, while I expected it to be DUP and stumbled on this wiki article. Can't find a reason for why a SSD would be different? Cheers, Sjoerd -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
