FreeNAS/ZFS woes (was Re: Is bcache ready for enterprise production?)

[Alan Johnson]

On Fri, Aug 15, 2014 at 11:35 AM, Tom Buskey <tom at buskey.name> wrote:

> I've never used FreeNAS, but I've used ZFS quite a bit.
>
> I've used it natively on Solaris at work and on Ubuntu with ZFS on Linux
> at home.
>
> I've been very happy with it.  There is information out there on
> tuning/not tuning on Solaris.  ZFS on Linux (and BSD) has different tunings.
>
> From the short skim I just did on bcache and its support in CentOS 7, it
> sounds like it's much less evolved then ZFS on Linux or FreeNAS.
>

bcache is certainly newer than ZFS.  It started in part as a response to
the caching features ZFS offers, IIRC.  It is also arbitrarily simpler than
ZFS, meant to be a bolt on to any block device storage management you are
already doing, not a full replacement.  In my case, it would be a software
36TB RAID6 as the backing device with one hot spare, a 500GB SSD mirror for
the cache device, with LVM and mostly ext4 on top of that.

Googling around for alternatives, I came across
*Why We Recommend Against OpenFiler
<http://community.spiceworks.com/topic/373443-why-we-recommend-against-openfiler>
​.* I don't know the author from Adam, but he come across as very
knowledgeable to me and he says this in response to one of the comments:


The biggest advantage of FreeNAS is that it offers ZFS which can be very
cool but ZFS has so much [hype] around it that it tends to cause bad
decision making, a [belief] that parity RAID has been magically fixed [e.g]
and people forget that the biggest hype is current ZFS which is Solaris
only, [FreeNAS] is an older version.


That was from a year ago though.  I don't know if it holds true in FreeNAS
9.2, which I had upgraded to long before my box blew up.​  Regardless, the
Solaris experience is likely to be very different.  I would be curious if
you could setup a test to see how ZFS on Solaris handles deleting zvols
from a deduplicated zpool.
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