On Mon, May 21, 2018 at 04:04:18AM +1000, Andrew McGlashan wrote:
Perhaps a better question for a new thread, but it would be interesting to know whether or not the whole ECC only for ZFS is really a thing and if it gives anybody grief without ECC.
ECC RAM is recommended, but not essential. I've been running ZFS without ECC RAM on my home systems since at least 2010 without any RAM-related dramas. Occasional disk problems, yeah, but that's why I run ZFS - so I don't have to care too much if a drive dies - I can replace it without losing anything valuable (i.e. my data) For **HOME** use, If you can get ECC RAM at a decent price, at not too much of a premium over non-ECC RAM then get it. If not, then don't worry too much about it. For non-home use, probably best to go with ECC RAM. Note that non-ECC RAM is typically available in faster speeds than ECC. ECC seems to max at about 2400MHz at the moment. non-ECC goes to 3600 or even higher. This doesn't make much difference in actual real-world performance unless you're using a Ryzen or Threadripper CPU - they really benefit from faster RAM speeds. More accurately, they're performance is limited by slow RAM.
Aside from using btrfs or ZFS.... I cannot understand opposition to lvm, it's wonderful.
LVM is wonderful. ZFS is wonderfuller. btrfs would be too, if it could be trusted not to lose your data.
If I need to increase the size of a file system, then I resize the lv and then use 'resize2fs' and it magically gets larger -- in this case, I can do so on-line as well (without unmounting the file system). I rarely shrink volumes, but it is possible, just be careful whenever you resize volumes, especially when shrinking to get your process 100% correct so you don't screw up the file system.
You don't need to mess around with resizing anything with either zfs or btrfs. The pool is shared amongst all datasets on it. Just create datasets (zfs) or sub-volumes (btrfs) as you need them. IIRC, btrfs doesn't have any quota or reservation mechanism, but zfs does. You can set a quota to limit how much space a dataset can use (e.g. limit your videos to 1TB) and you can also reserve a minimum amount of space (e.g. so that no matter what else is using disk space, /var/log will have a guaranteed minimum of 50GB available to it). Quotas and reservations are "soft" - i.e. they can be changed up or down at any time with just a single command. you can also have a dataset mounted anywhere in the filesystem you like. e.g. zfs create -o mountpoint=/var/cache/apt/archives -o compression=none ganesh/apt That creates a dataset called "apt" on pool "ganesh" that will be auto-mounted at /var/cache/apt/archives. compression is disabled on it because there's no need to waste CPU cycles trying to recompress .deb files. You can change the mount point any time too with "zfs set -o mountpoint=...." craig -- craig sanders <cas@taz.net.au>