ZFS Defrag

[sukerman]

Hi All,

root@db1:~# zpool list NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT pool 1.04T 579G 485G - - 67% 54% 1.00x ONLINE - root@db1:~#

A couple of questions please:

1) This is a NVME datacenter SSD. Is fragmentation worth worrying about for mysql usage?
2) I heard that you can defrag by zfs sending the data to another pool. Can you achieve the same by 'moving' the disk to another dataset via the proxmox GUI?

Thanks,

Jack.

 

[aaron]

Since ZFS is copy on write, its usage of the disk space will fragment with time. With SSDs I really would not worry about the fragmentation as the access times will always be in the same range, opposite to HDDs which need to move their RW heads to get to the data.

 

[LnxBil]

I heard that you can defrag by zfs sending the data to another pool.

Another dataset within the same pool is fine and will defrag it. Best defragging experience is to have only one snapshot in order to not having fragmentation to begin with.