[ceph-users] Another OSD broken today. How can I recover it?

Ronny Aasen ronny+ceph-users at aasen.cx
Tue Dec 5 13:54:08 PST 2017


just as long as you are aware that size=3, min_size=2 is the right 
config for everyone except those that really know what they are doing.
and if you ever run min_size=1 you better be expecting to corrupt your 
cluster sooner or later.

Ronny

On 05.12.2017 21:22, Denes Dolhay wrote:
> Hi,
>
> So for this to happen you have to lose another osd before backfilling 
> is done.
>
>
> Thank You! This clarifies it!
>
> Denes
>
>
>
> On 12/05/2017 03:32 PM, Ronny Aasen wrote:
>> On 05. des. 2017 10:26, Denes Dolhay wrote:
>>> Hi,
>>>
>>> This question popped up a few times already under filestore and 
>>> bluestore too, but please help me understand, why this is?
>>>
>>> "when you have 2 different objects, both with correct digests, in 
>>> your cluster, the cluster can not know witch of the 2 objects are 
>>> the correct one."
>>>
>>> Doesn't it use an epoch, or an omap epoch when storing new data? If 
>>> so why can it not use the recent one?
>>>
>>>
>>
>>
>> this have been discussed a few times on the list. generally  you have 
>> 2 disks.
>>
>> first disk fail. and writes happen to the other disk..
>>
>> first disk recovers, and second disk fail before recovery is done. 
>> writes happen to second disk..
>>
>> all objects have correct checksum. and both osd's think they are the 
>> correct one. so your cluster is inconsistent.  so bluestore checksums
>> does not solve this problem, both objects are objectivly "correct" :)
>>
>>
>> with min_size =2 the cluster would not accept a write unless 2 disks 
>> accepted the write.
>>
>> kind regards
>> Ronny Aasen
>>
>>
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>
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