Thanks christian.. Got clear about the concept.. thanks very much :)
On Tue, Nov 11, 2014 at 5:47 PM, Loic Dachary <loic@xxxxxxxxxxx> wrote:
Hi Christian,
On 11/11/2014 13:09, Christian Balzer wrote:
> On Tue, 11 Nov 2014 17:14:49 +0530 Mallikarjun Biradar wrote:
>
>> Hi all
>>
>> When Issued ceph osd dump it displays weight for that osd as 1 and when
>> issued osd tree it displays 0.35
>>
>
> There are many threads about this, google is your friend. For example:
> https://www.mail-archive.com/ceph-users@xxxxxxxxxxxxxx/msg11010.html
>
> In short, one is the CRUSH weight (usually based on the capacity of the
> OSD), the other is the OSD weight (or reweight in the tree display).
>
> For example think about a cluster with 100 2TB OSDs and you're planning to
> replace them (bit by bit) with 4TB OSDs. But the hard disks are the same
> speed, so if you would just replace things, more and more data would
> migrate to your bigger OSDs, making the whole cluster actually slower.
> Setting the OSD weight (reweight) to 0.5 for the 4TB OSDs (untiil the
> replacement is complete) will result in them getting the same allocation as
> the 2TB ones, keeping things even.
It is a great example. Would you like to add it to http://ceph.com/docs/giant/rados/operations/control/#osd-subsystem ? If you do not have time, I volunteer to do it :-)
Cheers
Loïc Dachary, Artisan Logiciel Libre
>
> Christian
>
>> output from osd dump:
>> { "osd": 20,
>> "uuid": "b2a97a29-1b8a-43e4-a4b0-fd9ee351086e",
>> "up": 1,
>> "in": 1,
>> "weight": "1.000000",
>> "primary_affinity": "1.000000",
>> "last_clean_begin": 0,
>> "last_clean_end": 0,
>> "up_from": 103,
>> "up_thru": 106,
>> "down_at": 0,
>> "lost_at": 0,
>> "public_addr": "10.242.43.116:6820\/27623",
>> "cluster_addr": "10.242.43.116:6821\/27623",
>> "heartbeat_back_addr": "10.242.43.116:6822\/27623",
>> "heartbeat_front_addr": "10.242.43.116:6823\/27623",
>> "state": [
>> "exists",
>> "up"]}],
>>
>> output from osd tree:
>> # id weight type name up/down reweight
>> -1 7.35 root default
>> -2 2.8 host rack6-storage-5
>> 0 0.35 osd.0 up 1
>> 1 0.35 osd.1 up 1
>> 2 0.35 osd.2 up 1
>> 3 0.35 osd.3 up 1
>> 4 0.35 osd.4 up 1
>> 5 0.35 osd.5 up 1
>> 6 0.35 osd.6 up 1
>> 7 0.35 osd.7 up 1
>> -3 2.8 host rack6-storage-4
>> 8 0.35 osd.8 up 1
>> 9 0.35 osd.9 up 1
>> 10 0.35 osd.10 up 1
>> 11 0.35 osd.11 up 1
>> 12 0.35 osd.12 up 1
>> 13 0.35 osd.13 up 1
>> 14 0.35 osd.14 up 1
>> 15 0.35 osd.15 up 1
>> -4 1.75 host rack6-storage-6
>> 16 0.35 osd.16 up 1
>> 17 0.35 osd.17 up 1
>> 18 0.35 osd.18 up 1
>> 19 0.35 osd.19 up 1
>> 20 0.35 osd.20 up 1
>>
>> Please help me to understand this
>>
>> -regards,
>> Mallikarjun Biradar
>
>
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