The first question that was asked was whether many snapshots slow the system down. The answer is probably not. When developing my etbemon monitoring system I made the BTRFS monitor alert by default on more than 500 subvolumes (usually snapshots) as I had noticed performance problems with 1000+. You have less than that and ZFS has been optimised for performance more than BTRFS so it shouldn't be a problem. http://cdn.msy.com.au/Parts/PARTS.pdf The next thing is that 344G is not much space by today's standards. It's large enough that if installed in 2016 that probably isn't SSD, but small enough to easily fit on modern SSDs. MSY has 1TB SSDs starting at $135 and 2TB SSDs starting at $289. Get a couple of those and transfer the filesystem to them and it will be much faster. Also fragmentation doesn't matter on SSD. On Thursday, 20 August 2020 8:23:25 PM AEST Colin Fee via luv-main wrote:
sudo zpool list
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT alexandria 344G 332G 11.8G - 69% 96% 1.00x ONLINE -
Thanks for the reply. Above line is the most telling data and so I take back what I said before, this is likely the cause given it's your home volume. It's very full!
Your pool is at 96% capacity and 69% fragmented. The 96% is the biggest issue, there is (was?) a rule-of-thumb guid with copy-on-write filesystems, of which ZFS is an example, that you should keep the used capacity below 80%.
The amount of space you need to keep free varies a lot depending on the data type and usage. For example I run a ZFS server that regularly goes to 98% capacity with no problems, it is almost entirely used for 20MB files. Lots of files the same size means fragmentation isn't a big problem and large files written contiguously means it's easy for the filesystem to write them contiguously to disk. That is however an unusual corner case. For a /home 96% used is probably really bad for performance. You might get something useful from the following command: du /home|sort -n|tail -50
alexandria/home 1.02G 332G 90.4G 242G 0 0
In the pool, your one dataset 'alexandria/home', the snapshots are 90.4G of 332G or 27%, so not the full culprit. The fact the disk is nearly full is.
Possible things to do....
Make a backup first!! or several.
https://www.officeworks.com.au/shop/officeworks/c/technology/hard-drives-dat... Yes, always have lots of backups! Officeworks has some reasonable options for USB attached backup devices. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/