On Friday, 9 March 2018 1:04:13 PM AEDT Craig Sanders via luv-main wrote: > I forgot to mention one very useful difference between 1. partitions & LVM > Logical Volumes (LV) and 2. btrfs sub-volumes & ZFS datasets. > > Partitions & LVs are created with a fixed size. The size can be changed > later, but if you create a 50G /data partittion and a 100G /home partition > it's easily possible to have one or the other partition being full while the > other has plenty of space. > > Changing the size of a partition/LV requires changing both the size of the > partition or LV AND changing the size of the filesystem that's on > it. This isn't too difficult but does require some caution and attention to > detail. It's recommended to make sure you have a recent backup in case you > make a mistake.
Some filesystems like XFS don't support reducing the size at all. So LVM in that case is good for extending but can never reduce the size. Older filesystems like XFS and ext[234] have a fixed table of Inodes which will be increased linearly with increases in overall size which may or may not be what you want. > btrfs has btrfs-quota and btrfs-qgroup commands to control subvolume size > limits. I've never used them, so can't say any more than that they exist. > > BTW, The btrfs-quota man page says "When the quotas are turned on, they > affect all extent processing, taking a performance hit. It is not > recommended to turn on qgroups unless the user intends to actually use > them." They probably don't work well due to lack of testing. Last time I played with them I found a bug that made them unusable on my system in 5 minutes. > With ZFS, you can set a maximum size (quota) for a dataset (e.g. you might > limit Δ‘ata/videos to using no more than 200G). You can also reserve space in > the pool for a dataset to prevent any other dataset from using the reserved > space - i.e. to guarantee that a dataset will have a minimum amount of > space available to it, no matter what else is stored on the pool. Unlike BTRFS, you can expect every feature of ZFS to just work. It may be a total PITA to get it working, it may not be something you even want to use (EG ZFS control of Samba configuration), but it will work if you do the right thing. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ _______________________________________________ luv-main mailing list luv-main@luv.asn.au https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main
