Re: OSD replacement feature

[David Zafman <dzafman@redhat.com>]

That is correct.  The goal is to only refill the replacement OSD disk.  
Otherwise, if the OSD is only down for less than 
mon_osd_down_out_interval (5 min default) or noout is set, no other data 
movement would occur.

David

On 11/23/15 8:45 PM, Wei-Chung Cheng wrote:
> 2015-11-21 1:54 GMT+08:00 David Zafman <dzafman@redhat.com>:
>> There are two reasons for having a ceph-disk replace feature.
>>
>> 1. To simplify the steps required to replace a disk
>> 2. To allow a disk to be replaced proactively without causing any data
>> movement.
> Hi David,
>
> It good to without causing any data movement when we want to replaced
> failure osd.
>
> But I don't have any idea to complete it, could you give some opinions?
>
> I though if we want to replace failure we must move the object data on
> failure osd to new(replacement) osd?
>
> Or I got some misunderstanding?
>
> thanks!!!
> vicente
>
>> So keeping the osd id the same is required and is what motivated the feature
>> for me.
>>
>> David
>>
>>
>> On 11/20/15 3:38 AM, Sage Weil wrote:
>>> On Fri, 20 Nov 2015, Wei-Chung Cheng wrote:
>>>> Hi Loic and cephers,
>>>>
>>>> Sure, I have time to help (comment) on this feature replace a disk.
>>>> This is a useful feature to handle disk failure :p
>>>>
>>>> An simple step is described on http://tracker.ceph.com/issues/13732 :
>>>> 1. set noout flag - if the broken osd is primary osd, could we handle
>>>> well?
>>>> 2. stop osd daemon and we need to wait the osd actually down. (or
>>>> maybe use deactivate option with ceph-disk)
>>>>
>>>> these two above step seems OK.
>>>> about handle crush map, should we remove the broken osd out?
>>>> If we do that, why we set noout flag? It still trigger re-balance
>>>> after we remove osd from crushmap.
>>> Right--I think you generally want to do either one or the other:
>>>
>>> 1) mark osd out, leave failed disk in place.  or, replace with new disk
>>> that re-uses the same osd id.
>>>
>>> or,
>>>
>>> 2) remove osd from crush map.  replace with new disk (which gets new osd
>>> id).
>>>
>>> I think re-using the osd id is awkward currently, so doing 1 and replacing
>>> the disk ends up moving data twice.
>>>
>>> sage
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