From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felix Blanke Subject: Re: Suggestion for sticky-compression mount setting (default mount options) Date: Sat, 5 Feb 2011 13:18:46 +0100 Message-ID: <20110205131846.0000748c@unknown> References: <1296873843.7800.36.camel@KWOLFF03> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linux-btrfs@vger.kernel.org To: Kirk Wolff Return-path: In-Reply-To: <1296873843.7800.36.camel@KWOLFF03> List-ID: Hi, I don't think that the fs is a good place to store default mountoptions. If you want to auto mount usb devices with compression, just write a udev rule or whatever ubuntu uses to mount usb devices. Regards, Felix Am Fri, 04 Feb 2011 20:44:03 -0600 schrieb Kirk Wolff : > As I've been using btrfs with an external USB drive, I wonder how to > handle efficiently the compression setting. When I plug a drive in to > ubuntu, it is automatically mounted. Its mounted without the > compression option as its not in fstab. I don't see it as desirable > to install each usb drive in fstab on each computer that it may be > used just so that compression is automatically enabled. In > discussion with cjb on irc, I came to realize that the compression > setting shouldn't be filesystem-wide therefore it doesn't make sense > to have default mount options for an entire btrfs filesystem as you > may want compression on one subvolume and not on another. Therefore, > it seems to me that default mount options should be able to be > configured for each subvolume. If you follow this idea through, this > means that you would need to be able to both override each of the > default mount options from the mount command (or fstab). For > example, if a subvolume has its default mount option set to compress, > you should be able to disable compression if you manually mount it > with "-o nocompress". If mount default mount options were able to be > configured through btrfs for each subvolume, then for the case when > you have a simple USB drive that you're using for backups, the > default subvolume could have compress automatically set when its > plugged into a PC. Then you can use snapshots alongside the default > subvolume to perform a type of differential backups (similar to > rsnapshot, but using COW instead of hard links). I can guess there > are people out there that may want other mount options to be carried > around with the subvolume such as disabling COW or whatever. What > are your thoughts on the above? Please advise. > > - Kirk >