Re: cephfs-data-scan tool

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On Thu, Sep 27, 2018 at 11:34 AM Sergey Malinin <hell@xxxxxxxxxxx> wrote:
>
> Can such behaviour be related to data pool cache tiering?

Yes -- if there's a cache tier in use then deletions in the base pool
can be delayed and then happen later when the cache entries get
expired.

You may find that for a full scan of objects in the system, having a
cache pool actually slows things down quite a lot, due to the overhead
of promoting things in and out of the cache as we scan.

John

>
>
> > On 27.09.2018, at 13:14, Sergey Malinin <hell@xxxxxxxxxxx> wrote:
> >
> > I'm trying alternate metadata pool approach. I double checked that MDS servers are down and both original and recovery fs are set not joinable.
> >
> >
> >> On 27.09.2018, at 13:10, John Spray <jspray@xxxxxxxxxx> wrote:
> >>
> >> On Thu, Sep 27, 2018 at 11:03 AM Sergey Malinin <hell@xxxxxxxxxxx> wrote:
> >>>
> >>> Hello,
> >>> Does anybody have experience with using cephfs-data-scan tool?
> >>> Questions I have are how long would it take to scan extents on filesystem with 120M relatively small files? While running extents scan I noticed that number of objects in data pool is decreasing over the time. Is that normal?
> >>
> >> The scan_extents operation does not do any deletions, so that is
> >> surprising.  Is it possible that you've accidentially left an MDS
> >> running?
> >>
> >> John
> >>
> >> John
> >>
> >>> Thanks.
> >>> _______________________________________________
> >>> ceph-users mailing list
> >>> ceph-users@xxxxxxxxxxxxxx
> >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
>
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