You should subtract buffers and cache from the used memory to get a more
accurate representation of how much memory is actually available to
processes. In this case that puts you around 22G of used - or a better term
might be unavailable memory. Buffers and cache can be reallocated when
needed - it's just Linux taking advantage of memory under the theory why
not use it if it's there? Memory is fast so Linux will take advantage of it.

With 72 OSD's 22G of memory puts you below the 500MB/daemon that you've
mentioned so I don't think you have anything to be concerned about.

___

John Petrini

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On Tue, Feb 14, 2017 at 11:24 PM, Khang Nguyễn Nhật <
[email protected]> wrote:

> Hi Sam,
> Thank for your reply. I use BTRFS file system on OSDs.
> Here is result of "*free -hw*":
>
>                    total         used          free        shared
> buffers       cache     available
> Mem:           125G         58G         31G        1.2M        3.7M
>   36G         60G
>
> and "*ceph df*":
>
> GLOBAL:
>     SIZE     AVAIL     RAW USED     %RAW USED
>     523T      522T        1539G          0.29
> POOLS:
>     NAME                           ID     USED     %USED     MAX AVAIL
> OBJECTS
>     ............
>     default.rgw.buckets.data  92     597G      0.15              391T
>        84392
>     ............
>
> I was reviced this a few minutes ago.
>
> 2017-02-15 10:50 GMT+07:00 Sam Huracan <[email protected]>:
>
>> Hi Khang,
>>
>> What file system do you use in OSD node?
>> XFS always use Memory for caching data before writing to disk.
>>
>> So, don't worry, it always holds memory in your system as much as
>> possible.
>>
>>
>>
>> 2017-02-15 10:35 GMT+07:00 Khang Nguyễn Nhật <
>> [email protected]>:
>>
>>> Hi all,
>>> My ceph OSDs is running on Fedora-server24 with config are:
>>> 128GB RAM DDR3, CPU Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz, 72 OSDs
>>> (8TB per OSD). My cluster was use ceph object gateway with S3 API. Now, it
>>> had contained 500GB data but it was used > 50GB RAM. I'm worry my OSD will
>>> dead if i continue put file to it. I had read "OSDs do not require as
>>> much RAM for regular operations (e.g., 500MB of RAM per daemon instance);
>>> however, during recovery they need significantly more RAM (e.g., ~1GB per
>>> 1TB of storage per daemon)." in Ceph Hardware Recommendations. Someone
>>> can give me advice on this issue? Thank
>>>
>>> _______________________________________________
>>> ceph-users mailing list
>>> [email protected]
>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>>
>>>
>>
>
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>
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