On 8/24/06, Matthew Ahrens <[EMAIL PROTECTED]> wrote:
On Thu, Aug 24, 2006 at 07:07:45AM -0700, Joe Little wrote:
> We finally flipped the switch on one of our ZFS-based servers, with
> approximately 1TB of 2.8TB (3 stripes of 950MB or so, each of which is
> a RAID5 volume on the adaptec card). We have snapshots every 4 hours
> for the first few days. If you add up the snapshot references it
> appears somewhat high versus daily use (mostly mail boxes, spam, etc
> changing), but say an aggregate of no more than 400+MB a day.
>
> However, zfs list shows our daily pool as a whole, and per day we are
> growing by .01TB, or more specifically 80GB a day. That's a far cry
> different than the 400MB we can account for. Is it possible that
> metadata/ditto blocks, or the like is trully growing that rapidly. By
> our calculations, we will triple our disk space (sitting still) in 6
> months and use up the remaining 1.7TB. Of course, this is only with
> 2-3 days of churn, but its an alarming rate where before on the NetApp
> we didn't see anything close to this rate.
How are you calculating this 400MB/day figure? Keep in mind that space
"used" by each snapshot is the amount of space unique to that snapshot.
Adding up the space "used" by all your snapshots is *not* the amount of
space that they are all taking up cumulatively. For leaf filesystems
(those with no descendents), you can calculate the space used by
all snapshots as (fs's "used" - fs's "referenced").
How many filesystems do you have? Can you send me the output of 'zfs
list' and 'zfs get -r all <pool>'?
How much space did you expect to be using, and what data is that based
on? Are you sure you aren't writing 80GB/day to your pool?
--matt
well, by deleting my 4-hourlies I reclaimed most of the data. To
answer some of the questions, its about 15 filesystems (decendents
included). I'm aware of the space used by snapshots overlapping. I was
looking at the total space (zpool iostat reports) and seeing the diff
per day. The 400MB/day was be inspection and by looking at our nominal
growth on a netapp.
It would appear that if one days many snapshots, there is an initial
quick growth in disk usage, but once those snapshot meet their
retention level (say 12), the growth would appear to match our typical
400MB/day. Time will prove this one way or other. By simply getting
rid of hourly snapshots and collapsing to dailies for two days worth,
I reverted to only ~1-2GB total growth, which is much more in line
with expectations.
For various reasons, I can't post the zfs list type results as yet.
I'll need to get the ok for that first.. Sorry..
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