On Sat, Jan 18, 2020 at 01:20:39PM +1100, pushin.linux wrote:
I have elected to start with a Ubuntu 18.04 LTS desktop install.The Raid drives were picked up, ie are available, but does the balance command need to be issued again?
You only need to run 'btrfs balance' when you're changing the number and/or size of drives (or partitions) in the btrfs array. The command re-balances all of the data on the array, roughly-equally across all the drives. So, if you're not adding drives to the array, you don't need to re-balance it. (btw, 'btrfs balance' is the one feature that btrfs has that I wish zfs had)
I had two lines to set up the raid and balance them at the start.
IIRC, I think I advised you to do something like: 1. create a degraded btrfs array with just one of the drives; 2. copy your data to it; 3. add another drive to the btrfs array with 'btrfs add'; 4. re-balance the data so that it's on both drives with 'btrfs balance'. If so, that'll be why you have two commands written down.
I suspect that without those commands only one drive will be written to.
nope. This time around, your btrfs array for /data ALREADY EXISTS, so you don't have to do any of that. And you certainly SHOULD NOT run mkfs.btrfs, that would erase your current btrfs array and re-format it. All you need to do this time is add an entry to /etc/fstab so that it mounts correctly on boot. Something like the following: UUID="c0483385-ca6f-abb3-aeeb-94793439a637" /data btrfs defaults,relatime 0 0 run 'blkid' to find the correct uuid for your /data fs and use it instead of the bogus one in the example above. craig -- craig sanders <cas@taz.net.au>