On Mon, 6 Feb 2012, Mike O'Connor wrote:
On 6/02/12 12:20 PM, Toby Corkindale wrote:
I'm giving btrfs another go now; pity about losing the block-based dedup (which is great when you have a lot of virtual machine images), but the overhead just wasn't worth it for me.
One thing I'm already struggling to find in btrfs is simply to work out how much space a snapshot is consuming! Anyone?
As I understand it, snapshots them selves use 0% disk space, but of cause the storage required to keep the copy will be locked, but because of the way it does this its still a very small amount of space.
Bottom post and trim please. Have a btrfs filesystem with 4GB on it. Snapshot it (1) Allocate a 1GB and 3GB file. Take a snapshot (2). Delete the 1GB file. How much space is allocate within btrfs, how much space is the current filesystem taking up, how much space did snapshot 2 take up over snapshot 1, and how much space would be freed by deleting snapshot 2 are all seperate questions. (I have a 2.5year old backuppc instance at home where I have similar questions. I have just filled up my disk, never having had to purge any old snapshots outside of the normal trimming algorithm I gave it. Now that I have filled it, I don't want to purge the most historical information out of it. I know there are some intermediate snapshots where I allocated large temporary files that I can safely purge from the backups. What is the mimimal set of backups that can be purged that will free up the maximal space that I need to allow me to restart the backups without buying more disk?). -- Tim Connors