Re: memory consumption by osd

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Depending on your kernel version, MemFree can be misleading.  Attend to the value of MemAvailable instead.

Your OSDs all look to be well below the target, I wouldn’t think you have any problems.  In fact 256GB for just 10 OSDs is an embarassment of riches.  What type of drives are you using, and what’s the cluster used for?  If anything I might advise *raising* the target.

You might check tcmalloc usage

https://ceph-devel.vger.kernel.narkive.com/tYp0KkIT/ceph-daemon-memory-utilization-heap-release-drops-use-by-50

but I doubt this is an issue for you.

> What's taking that much buffer?
> # free -h
>              total        used        free      shared  buff/cache   available
> Mem:          251Gi        31Gi       1.8Gi       1.6Gi       217Gi       215Gi
> 
> # cat /proc/meminfo 
> MemTotal:       263454780 kB
> MemFree:         2212484 kB
> MemAvailable:   226842848 kB
> Buffers:        219061308 kB
> Cached:          2066532 kB
> SwapCached:          928 kB
> Active:         142272648 kB
> Inactive:       109641772 kB
> ......
> 
> 
> Thanks!
> Tony
> ________________________________________
> From: Tony Liu <tonyliu0592@xxxxxxxxxxx>
> Sent: March 27, 2021 01:25 PM
> To: ceph-users
> Subject:  memory consumption by osd
> 
> Hi,
> 
> Here is a snippet from top on a node with 10 OSDs.
> ===========================
> MiB Mem : 257280.1 total,   2070.1 free,  31881.7 used, 223328.3 buff/cache
> MiB Swap: 128000.0 total, 126754.7 free,   1245.3 used. 221608.0 avail Mem
> 
>    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
>  30492 167       20   0 4483384   2.9g  16696 S   6.0   1.2 707:05.25 ceph-osd
>  35396 167       20   0 4444952   2.8g  16468 S   5.0   1.1 815:58.52 ceph-osd
>  33488 167       20   0 4161872   2.8g  16580 S   4.7   1.1 496:07.94 ceph-osd
>  36371 167       20   0 4387792   3.0g  16748 S   4.3   1.2 762:37.64 ceph-osd
>  39185 167       20   0 5108244   3.1g  16576 S   4.0   1.2 998:06.73 ceph-osd
>  38729 167       20   0 4748292   2.8g  16580 S   3.3   1.1 895:03.67 ceph-osd
>  34439 167       20   0 4492312   2.8g  16796 S   2.0   1.1 921:55.50 ceph-osd
>  31473 167       20   0 4314500   2.9g  16684 S   1.3   1.2 680:48.09 ceph-osd
>  32495 167       20   0 4294196   2.8g  16552 S   1.0   1.1 545:14.53 ceph-osd
>  37230 167       20   0 4586020   2.7g  16620 S   1.0   1.1 844:12.23 ceph-osd
> ===========================
> Does it look OK with 2GB free?
> I can't tell how that 220GB is used for buffer/cache.
> Is that used by OSDs? Is it controlled by configuration or auto scaling based
> on physical memory? Any clarifications would be helpful.
> 
> 
> Thanks!
> Tony
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