The L2ARC is just a read cache that works alongside the regular ARC stored in RAM. If the L2ARC device malfunctions then you might see a performance hit, but your pool will remain intact. All L2ARC reads are checked for integrity, so invalid data will be rejected and read from the pool directly instead.<p>ZFS can even tolerate the loss of a SLOG device as long as A) the SLOG is not currently being read to rebuild after a crash and B) all writes that occurred before the SLOG was lost have been fully flushed to the pool disks.