I’m installing a new TrueNAS Core server with 8 bays. I have 6 disks of rust for the ZFS pool (3 2-disk mirror vdevs), 1 SSD for the OS, and 1 leftover SSD which long-term I intend to use as L2ARC.

My question is, for migrating my existing data (about 10TB) across the LAN (coming from a RAIDZ2 array), will it be much benefit to temporarily use that spare SSD as a SLOG? AFAIK SLOG is only useful for synchronous writes and since the new server won’t yet be in production there won’t be any contention for iops.

And does the answer change if I decide to use zfs send vs eg rsync?