John Goerzen posted on Thu, 05 Dec 2013 11:52:04 -0600 as excerpted: > Hello, > > I have observed extremely slow metadata performance with btrfs. This may > be a bit of a nightmare scenario; it involves untarring a backup of > 1.6TB of backuppc data, which contains millions of hardlinks and much > data, onto USB 2.0 disks. > Is this behavior known and expected? Yes. Btrfs doesn't do well with lots of hardlinks and indeed until relatively recently had a hard-limit on the number of hardlinks possible within a directory, that hardlink-heavy use-cases would regularly hit. That was worked around, but there's an additional level of indirection once the first level link-pool is filled, and you're not the first to have observed that btrfs performance isn't the best in that sort of scenario. That's known. Other filesystems will probably do quite a bit better for hardlink style backups and other hardlink-heavy use-cases. Either that, or consider using btrfs, but with some other form of backup, possibly btrfs snapshots, or COW reflinks. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
