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] > <javascript:_e(%7B%7D,'cvml','[email protected]');>] > *Sent:* 19 June 2014 13:53 > *To:* Ryall, George (STFC,RAL,SC) > *Cc:* [email protected] > <javascript:_e(%7B%7D,'cvml','[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] > <javascript:_e(%7B%7D,'cvml','[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
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