I've been using this setup for a few weeks now and now believe that BTRFS sucks for SSDs. It's slow and locks up occasionally while the SSDs do massive amounts of copying (this is a COW filesystem after all), and runs out of space easily. Sort of. It's really just the funky way that BTRFS reports free space that encourages you to use it, thinking it's there, but BTRFS is really reporting twice as much as you've got. In other words, BTRFS has brain-damage that affects SSDs and you probably shouldn't be using it unless you really, really hate mdadm.
UPDATE 2012-07-16: After using this setup for less than one month, struggling with "ENOSPC" (error no space left on device) and deleting files to fix it, only to limp along for a few days before running out of space again, I must conclude that BTRFS is fit only for masochists in its current form. DO NOT USE THIS GUIDE. Go back to safe, usable xfs (or ext4) for /home and forget all about the following guide. In case anybody is wondering, here is the output of btrfs filesystem show:
- Code: Select all
Total devices 2 FS bytes used 47.33GB
devid 1 size 101.56GB used 101.56GB path /dev/sda2
devid 2 size 101.56GB used 101.56GB path /dev/sdb2
That math doesn't add up. Somebody is lying.... and I think we know who! It's btr-fscking-s. I had to fix it by deleting some of my last remaining files and "rebalancing" /home. If you can handle this kind of BS then proceed. If you'd rather have a useful, usable system then back to mdadm for you.
Hi! After going through several days of troubleshooting, reading dozens of forums, making every mistake you can think of, I've refined the installation process of Mint 13 and conquered some obstacles to suit my particular needs. If your needs are similar to mine this guide will save you a TON of time.
Some background: I jumped ship from Ubuntu after they crapped Unity all over the place. Moved to Kubuntu 11.10 but the non-stop printer-configuration crashes after upgrading to 12.04 necessitated a new setup. Tried the LiveCD of Mint 13 and was hooked. Now here we are.
So, take a look at this list and decide if your situation is similar to mine - and if it is, get ready for some fun
1. RAID1 is a priority. I've got a couple of 128GB SATA6 SSDs as /dev/sda and /dev/sdb and want the / and /home directories mirrored.
2. No ext4 /boot partitions or other weird stuff. We're going to have a / partition and a separate /home partition. Nothing too fancy.
3. Trying out BTRFS! Snapshots, growable, shrinkable, built-in RAID, you get it all. Now it's got fsck too.
4. Encrypted /home/myusername directory.
Now, out of the box Mint 13 will mangle a couple important things, which appear to be installer bugs related to BTRFS. Can't do RAID1. Can't do /home on btrfs. Can't do an encrypted user directory on btrfs. We'll work around these problems and make it perfect.