Options other than another pool?

TrueNAS General
,
1

Hi I wanted to check my thinking…

When I built my TrueNAS Scale 24.10 I created a pool with a single data vDev RAIDZ1:5 wide using 20TB SATA drives.
My old NAS had 8 x 6 TB SATA drives. I was thinking I would pull 5 of those and create a second data vDev as a RAIDZ1:5 wide to add more storage to the pool. With an assumption that over time I would expand the vDev of 20TB drives as (a) the need arises, (b) drive prices come down, (c) the ZFS feature matures/is tested in real world scenario’s and eventually I remove the 6 TB drive’s one day.

I understand that,

  1. vDev death = pool death
    That if 2 or more drives in the RAIDZ1 vDev failed it would take out the pool, so either remove the vDev cleanly or don’t add it in the first place.

  2. RAIDZ vDev’s can’t be removed
    I understand that ZFS can’t allow me to remove a RAIDZ vDev from a pool as there is no simple way to re-map the blocks to a different device, which ZFS can do with other layouts that allow it to use a hidden indirect device to re-map.

Is my best option to create the 6TB drives in a new pool so that when the time comes I move the data set to my main pool and kill the pool of 6 TB drives?

Thanks

MC

2

I think you have got this completely right.

If it were me, I would…

  1. Use the 6TB drives in a different pool.

  2. Use it to move the data off your 20TB drives and recreate that pool as RAIDZ2. For 5+ drives or 8TB+ size the rule-of-thumb is that you should use RAIDZ2 rather than RAIDZ1 to reduce the risk of more drives failing whilst you are doing the very long stressful resilvering after a single drive failure.

1 Like