Re: Btrfs and raw zvol-like partition
zvol (interface) does not just 'export raw device' but rather implements volume abstraction and integrates volume management into file-system. Regards, Andrey On Sun, Apr 12, 2009 at 11:26 AM, Sébastien Wacquiez s...@enix.org wrote: Hi, A nice feature is ZFS is the ZVOL layer, that permit you to export (directly) a raw device from your zfs pool of disc, with the benefit of powerful (growing!) snapshot and easy raid management from zfs. It's particulary usefull when you use it with virtual server, allowing you to centralize all your backup problematic, etc Does btrfs plan to support this kind of feature ? (please, don't tell me that lvm do, lvm just sucks when you make a snapshot of your disk, and lack of the growing, commit, rollback, diffsend feature). Thanks ! Sébastien Wacquiez PS : see http://opensolaris.org/os/community/zfs/source/zfstour.png if you don't know what zvol do. -- 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 -- 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
Re: Btrfs and raw zvol-like partition
Andrey Kuzmin a écrit : zvol (interface) does not just 'export raw device' but rather implements volume abstraction and integrates volume management into file-system. Yep. I suck at writing english, thanks for pointing that out :) I surely mislead myself, but I think that the volume management of ZFS could be done with file. Alloc on write ? Use sparse file. Resizing ? Append or truncate the file. Snapshot ? Snapshot the file. Another Volume ? An other file :) In fact, the two thinks that have to be done, for me, is : 1/ Optimise the different layer to bypass permission, acl, co, and surely the way data is written. 2/ Be able to export those file directly as block device. (Allowing some more optimisation :) ) It's why I called this feature export raw device (as in export raw file as block device). As I say, it could be emulated with file and loopback, but it'll surely be slow ... So I wanna know if btrfs plan to have those type of optimization (and the user land tools to simplify it's management). Regards, Sébastien Wacquiez -- 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
Re: btrfs and /proc/self/mountinfo
On Sun, Apr 12, 2009 at 07:35, David Zeuthen zeut...@gmail.com wrote: But we'd still need some kind of way of having the kernel tell user space what devices are currently claimed by the btrfs filesystem instance (and we'd need notifications on changes too). Otherwise we don't have enough information for the desktop shell and partitioning programs to let the user know that /dev/sdb2 or /dev/sdc1 or whatever is currently claimed by the 0:19 btrfs mount at /media/fedora-usb. One idea is to have a pollable file, /proc/fs/btrfs/devs, that maps from the dev_t of the btrfs filesystem instance (as used in /proc/self/mountinfo) to the set of dev_t for block devices currently claimed? E.g. for the example above we'd have /proc/fs/btrfs/devs: 0:19 8:18 Btrfs used to export some information in /sys/fs/btrfs/, this is disabled for now. Maybe we can possibly make it export something like: $ tree /sys/fs/btrfs/ /sys/fs/btrfs/ |-- 969d1386-a002-4c28-94f2-47be23f344e4 | |-- ba1532f3-849b-400b-9c76-2c9aee126c52 | | |-- device - ../../../devices/.../block/sda/sda3 | | |-- attribute1 | | |-- ... | `-- 45645656-849b-400b-9c76-2c9aee126c52 | |-- device - ../../../devices/.../block/sdb/sdb3 | |-- attribute1 | `-- 645645686-a002-4c28-94f2-47be23f344e4 |-- ... So you could look for a device link at the subvolume devices? Or if that does not fit for some reason, we could also add a btrfs class, to export details about the subvolumes. Thanks, Kay -- 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
