btrfs does handle mixed device sizes really well actually. And you're right, zfs is limited to the smallest drive x vdev width. The rest goes unused. You can do things like pre-slice the drives with sparse files and create zfs on those files, but then you'll load up those larger drives with a lot more iop requests and you may dramatically slow things down. It can expand a vdev by replacing drives with larger ones. The other drawback is the single-drive performance of a single vdev regardless of the number of drives in it. I love zfs for a lot of reasons, and dislike it for a lot too. I ultimately decided to use btrfs on my personal equipment because it promises to be more organic and my commodity hardware definitely likes to play the organic role. :)
On Wed, Oct 14, 2015 at 4:15 PM, Rich Freeman <[email protected]> wrote: > On Wed, Oct 14, 2015 at 4:53 PM, Donald Pearson > <[email protected]> wrote: >> >> Personally I would still recommend zfs on illumos in production, >> because it's nearly unshakeable and the creative things you can do to >> deal with problems are pretty remarkable. The unfortunate reality is >> though that over time your system will probably grow and expand and >> zfs is very locked in to the original configuration. Adding vdevs is >> a poor solution IMO. >> > > This is the main thing that has kept me away from zfs - you can't > modify a vdev, like you can with an md array or btrfs. I don't think > zfs makes use of all your space if you have mixed disk sizes in a > raid-z either - it works like mdadm. I'm not sure whether btrfs will > be any better in that regard (if I have 2x3TB and 3x1TB drives in a > RAID5 I should get 6TB of usable space, not 4TB, without messing with > partitioning). > > So, I am running raid1 btrfs in the hope that I'll be able to move to > something more efficient in the future. > > However, I would not personally be using raid5/6 for anything but pure > experimentation on btrfs anytime soon. I don't even trust the 4.1 > kernel series for btrfs at all just yet, and you're not going to be > running older than that for raid5/6. > > -- > Rich -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
