Is ZFS ready for prime time?
Matthew Seaman
m.seaman at infracaninophile.co.uk
Mon Nov 15 22:47:47 UTC 2010
On 15/11/2010 20:33, krad wrote:
> My gut feeling is no. I wouldn't put it on mission critical stuff yet. Its
> not that I have had any major bad experiences (x fingers) but im not aware
> of any major deployments of it in the wild. As a result I wouldnt feel safe
> being the 1st 8)
>
> What I would advise is to think carefully about what you actually need. If
> you dont really need zfs features, then fine go with ufs, as you can always
> migrate in the future. However if the features are useful to you and of
> enough of a benefit to justify I would advise going for a Solaris platform
> of some kind.
>
> If you are doing it on a budget, go for openindiana, but if you have a some
> budget, go for the safe option of solaris 10 u9.
>
I don't entirely agree with this. ZFS on FreeBSD is in good shape and
suitable for /some/ mission critical uses IMHO. You will gain all the
benefits of reliability, maintainability and flexibility that ZFS provides.
However:
* The versions of ZFS in RELEASE versions of FreeBSD aren't
brilliantly performant: you want recent 8.1-STABLE or above
if your need is for speed.
* FreeBSD itself doesn't have good support for being an iSCSI
provider, consequently the iSCSI related functions in ZFS are
not enabled. Similarly SCSI-target mode is in need of a bit of
love, and trying to use FreeBSD as a homebrew SAN over fibre
channel doesn't really work.
* ZFS (on any platform) is intrinsically slow for the sort of small
random IOs generated by RDBMSes. On the other hand, the data
integrity and update consistency guarantees are really good news
if your Database needs stability and correctness more than speed.
* The file synch-ing guarantees provided by ZFS are entirely
dependent on the behaviour of the underlying hardware -- if your
disk lies to the OS about having committed data to non-volatile
storage then nothing can really be promised. Or, looked at from a
different point of view: ZFS cannot make a silk purse out of a
sow's ear: it works most effectively with server-grade SATA or SAS
drives rather than commodity desktop hard drives.
Personally, I've converted to using a ZFS mirror pair of drives for
preference as my standard way to do a FreeBSD OS install for a general
purpose server. Exceptions are mostly due to speed requirements. Once
8.2-RELEASE hits the shelves in January (well, approximately January)
ZFS performance in RELEASE will be seen to have improved markedly, and I
expect to be using ZFS pretty much exclusively for general purpose installs.
On the other hand, if you need to build some sort of network file
server, then OpenIndiana or Solaris would be better choices with ZFS,
and are likely to remain better for some significant amount of time.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
JID: matthew at infracaninophile.co.uk Kent, CT11 9PW
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