-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 20/04/13 13:48, Hugo Mills wrote:> On Sat, Apr 20, 2013 at 01:17:06PM - -0700, Roger Binns wrote: >> Is there any particular reason why I can't use DUP for data? > > Technically, no. Performance is likely to suck if you use rotational > disks, and you may find some SSDs deduplicate blocks, making it fairly > pointless for those devices.
Wanting dup is because I care about resilience in the face of errors over performance, so I don't actually care how bad performance sucks. I only put data on SSDs that I can afford to lose (usually backed up to Dropbox/github/spinning disks). >> When I try to set it with balance there is a kernel message: >> >> btrfs: dup for data is not allowed > > What kernel and userspace versions are you using? I thought the > restriction had been removed at some point (but possibly I'm just > misremembering it). Whatever Ubuntu 12.10 ships with. Kernel package is 3.5.0.27.43 and btrfs-tools is 0.19+20120328-7ubuntu1. Note the message came from the kernel so it would appear to be solely to blame for refusing my request. > it can be quite hard to find every single implication of a feature when > that feature gets changd/updated. I'm more amused that someone went to the trouble of putting in kernel detection and messages plus updating the documentation in order to prevent using DUP for data! Roger -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAlFzBWEACgkQmOOfHg372QT5twCeI5KOgHYT1wcPNPtni9TYKQaG aeIAmQGw/nL/ziTDAu4gUJIFPwCLI5td =ABih -----END PGP SIGNATURE----- -- 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
