Best practices for ZFS setup for a strictly SSD based system?

Patrick M. Hausen hausen at
Tue Feb 9 16:14:12 UTC 2016

Hi, all,

while there is quite a bit of documentation on how to improve ZFS performance
by using a combination of rotating disks and SSDs, I have not found much about
an SSD only setup.

We are planning to try a hosting server with 8 SATA SSDs with ZFS. Things I am
not at all sure about:

*	Does the recommended limit of 6 disks for a RAIDZ2 still
	hold? 2x 4 disks is quite a bit of overhead, could I use all 8
	in one vdev and get away with it?
	(The maximum of 6 recommendation is in some old Sun doc)

*	Will e.g. MySQL still profit from residing on a mirror
	instead of a RAIDZ2, even if all disks are SSDs?

*	Does a separate ZIL and/or ARC cache device still
	make sense?

Any pointers or direct help greatly appreciated. Or should I take this to freebsd-fs@?

Thanks and best regards,
-- GmbH * Kaiserallee 13a * 76133 Karlsruhe
Tel. 0721 9109 0 * Fax 0721 9109 100
info at
Gf: Jürgen Egeling      AG Mannheim 108285

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