Re: cephfs-data-scan tool

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> 
> On 27.09.2018, at 15:04, John Spray <jspray@xxxxxxxxxx> wrote:
> 
> 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.

'forward' cache mode is still reported dangerous. Is it safe enough to switch to forward mode while doing recovery?


> 
> 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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