George, I'll look into writing up some additional detail. We do have a description for 'ceph df' here: http://ceph.com/docs/master/rados/operations/monitoring/#checking-a-cluster-s-usage-stats
On Thu, Jun 19, 2014 at 8:07 AM, Gregory Farnum <[email protected]> wrote: > Yeah, the journal is a fixed size; it won't grow! > > > On Thursday, June 19, 2014, <[email protected]> wrote: > >> Having looked at a sample of OSDs it appears that it is indeed the case >> that for every GB of data we have 9 GB of Journal. Is this normal? Or are >> we not doing some Journal/cluster management that we should be? >> >> >> >> >> >> George >> >> >> >> *From:* Gregory Farnum [mailto:[email protected]] >> *Sent:* 19 June 2014 13:53 >> *To:* Ryall, George (STFC,RAL,SC) >> *Cc:* [email protected] >> *Subject:* Re: [ceph-users] understanding rados df statistics >> >> >> >> The total used/available/capacity is calculated by running the syscall >> which "df" uses across all OSDs and summing the results. The "total data" >> is calculated by summing the sizes of the objects stored. >> >> >> >> It depends on how you've configured your system, but I'm guessing the >> markup is due to the (constant size) overhead of your journals. Or anything >> else which you might have stored on the disks besides Ceph? >> >> -Greg >> >> >> On Thursday, June 19, 2014, <[email protected]> wrote: >> >> Hi all, >> >> I’m struggling to understand some Ceph usage statistics and I was hoping >> someone might be able to explain them to me. >> >> >> >> If I run ‘rados df’ I get the following: >> >> # rados df >> >> pool name category KB objects clones >> degraded unfound rd rd KB wr wr KB >> >> pool-1 - 0 0 >> 0 0 0 0 0 >> 0 0 >> >> pool-2 - 2339809 1299 >> 0 0 0 300 540600 3301 >> 2340798 >> >> pool-3 - 4095749 14654 >> 0 0 0 3969 17256 3337952 >> 70296734 >> >> pool-4 - 1802832 39332 >> 0 0 0 0 0 >> 2205979 0 >> >> pool-5 - 193102485 82397 >> 0 0 0 668938 102410614 5230404 >> 254457331 >> >> total used 5402116076 137682 >> >> total avail 854277445084 >> >> total space 859679561160 >> >> >> >> Pools 2 and 4 have a size of 2, whilst pools 3 and 5 have a size of 3. >> >> >> >> ‘ceph status’ tells me the following stats: “192 GB data, 134 kobjects, >> 5151 GB used, 795 TB / 800 TB avail” >> >> >> >> The 192 GB of data is equal to the sum of the ‘KB’ column of the rados df >> data. The used and available numbers are the same the totals given by >> rados df. >> >> >> >> What I don’t understand is how we have used 5,151 GB of data. Given the >> sizes of each pool I would expect it to be closer to 572 GB (sum of the >> size of each pool multiplied by pool ‘size’) plus some overhead of some >> kind. This is a factor of 9 different. So my question is: what have I >> missed? >> >> >> >> Cheers, >> >> >> >> George Ryall >> >> >> Scientific Computing | STFC Rutherford Appleton Laboratory | Harwell >> Oxford | Didcot | OX11 0QX >> >> (01235 44) 5021 >> >> >> >> >> >> -- >> Scanned by iCritical. >> >> >> >> >> >> -- >> Software Engineer #42 @ http://inktank.com | http://ceph.com >> > > > -- > Software Engineer #42 @ http://inktank.com | http://ceph.com > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > -- John Wilkins Senior Technical Writer Intank [email protected] (415) 425-9599 http://inktank.com
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