On Sat, Mar 1, 2014 at 5:07 PM, Jason Belec <jasonbe...@belecmartin.com>wrote:
> Technically, what you qualify below is a truism under any hardware. ZFS is
> neither more or less susceptible to RAM failure as it has nothing to do
> with ZFS. Anything that gets written to the pool technically is sound. You
> have chosen a single possible point of failure, what of firmware, drive
> cache, motherboard, power surges, motion, etc.?
I'm sorry, but I'm not following your logic here. Are you saying that ZFS
doesn't use RAM so it can't be affected by it? ZFS likes lots of memory and
uses it aggressively. So my understanding is that large amounts of data are
more likely to be in memory with ZFS than with other file systems. If
Google's research is to believed then random memory errors are a lot more
frequent than you think that they are. As I understand it, ZFS does not
checksum data while it's in memory. (While there a debug flag to turn this
on, I'm betting that the performance hit is pretty big.) So how does RAM
failure or random bit flips have nothing to do with ZFS?
> RAM/ECC RAM is like consumer drives vs pro drives in your system, recent
> long term studies have shown you don't get much more for the extra money.
Do you have references to these studies? This directly conflicts with what
I've seen posted, with references, in other forums on the frequency of soft
memory errors, particularly on systems that run 24x7, and how ECC memory is
able to correct these random errors.
> I have been running ZFS in production using the past and current versions
> for OS X on over 60 systems (12 are servers) since Apple kicked ZFS loose.
> No systems (3 run ECC) have had data corruption or data loss.
That you know of.
> Some pools have disappeared on the older ZFS but were easily recovered on
> modern (current development) and past OpenSolaris, FreeBSD, etc., as I keep
> clones of 'corrupted' pools for such tests. Almost always, these were the
> result of connector/cable failure. In that span of time no RAM has failed
> 'utterly' and all data and tests have shown quality storage. In that time
> 11 drives have failed and easily been replaced, 4 of those were OS drives,
> data stored under ZFS and a regular clone of the OS also stored under ZFS
> just in case. All pools are backed-up/replicated off site. Probably a lot
> more than most are doing for data integrity.
> No this data I'm providing is not a guarantee. It's just data from someone
> who has grown to trust ZFS in the real world for clients that cannot lose
> data for the most part due to legal regulations. I trust RAM manufacturers
> and drive manufacturers equally, I just verify for peace of mind with ZFS.
I have an opinion of people who run servers with legal or critical
business data on it that do not use ECC memory but I'll keep it to myself.
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