On Tuesday, 6 March 2018 6:29:11 PM AEDT Craig Sanders via luv-main wrote:
On Mon, Mar 05, 2018 at 10:54:10PM +1100, Andrew Pam wrote:
[ ... ] it's also possible to set up mirroring using LVM, btrfs or ZFS if you prefer.
With btrfs or ZFS it's easy to add additional drives for more space later.
With ZFS you only add them one RAID set at a time and after adding that RAID set can't be changed. You can't just add a disk at a time as you do with BTRFS. Last time I checked BTRFS RAID-5 and RAID-6 wasn't reliable IMHO.
Also, both btrfs and ZFS support transparent compression - which can greatly increase effective capacity if most of your data is uncomressed or poorly-compressed. Not video or audio files, for example.
The last time I ran a medium size mail server on ZFS I didn't see a lot of compression. I think it was something like 40%. Usually large amounts of data means video files though.
There are so many other benefits to using either btrfs or ZFS (snapshots, error-detection and correction, sub-volumes aka datasets, and much more), that IMO there's little reason to use a plain RAID-1 + ext4 partition for anything except a separate /boot.
Particularly as the most common errors are silent corruption which can't be detected by a plan RAID and can only be stopped by BTRFS or ZFS. Sucks for people who don't use Unix.
ZFS has the advantage of more features, and greater reliability. It's not built in to the kernel, but most distros have the kernel module packaged as a dkms package (ubuntu and a few others take the legally dubious stance that the CDDL vs GPL license conflict isn't a problem, so include ZFS pre-compiled with their kernels already).
I don't think it's legally dubious. Oracle know exactly what they are doing, if Oracle thought it was bad they would have let them know. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/