Re:ZFS on Linux 0.7.13
by tomatocracy on Thursday March 07, 2019 @11:07AM
(#19329159)
Zfs does allow pools to be expanded by adding vdevs.
What it doesn’t allow is for raid sets to be expanded by replacing with larger disks one at a time. This can however be done with mirrored sets. Add new larger discs to the mirror set, wait for resilvering, remove older smaller discs, done.
0.8 will also bring the ability to remove vdevs so effectively shrink a pool through a similar (but slightly different) process.
But even though you can add vdevs, it doesn’t rebalance the mirror. This means your entire pool, albeit larger, is still slower.
(Unless this is a change that will be brought about in 0.8, I haven’t followed that closely).
Not quite right - you absolutely can expand raidz vdevs by replacing the disks one at a time. What you can't do is increase the "width" of the raidz, or seamlessly rebalance data between multiple vdevs.
ZFS is more stable, has the downside of not allowing expansion of volumes, and has the issue of not being upstreamed.
BTRfs has the option to expand volumes, is native to Linux, but has a wiff of unstability. Most notably with the persisting raid 5 write hole.
I haven't found a good choice yet. Though I think I'd go btrfs at the moment.