Re: [Moosefs-users] Write starvation

[Robert S. <rsa...@ne...>]

Hi Ricardo,

My guess is that the number of chunks that the chunkserver knows about 
has an influence on the memory usage. In my case mfschunkserver uses a 
bit more memory.

As reported by top:

USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
daemon     0 -19 3622m 3.4g  756 S 16.9  5.5 188:10.92 mfschunkserver
daemon     0 -19 8763m 8.5g  676 D 22.6 13.5   7766:43 mfschunkserver

daemon     0 -19 24.3g  24g  768 S 10.0 39.2 248:44.71 mfsmaster

I have seen mfsmount use around 1 GB of RAM too. This is the current 
usage on two servers where only read traffic happens.

root       4 -19  745m  51m  496 S  3.3  0.1 453:04.87 mfsmount
root       3 -19  684m  52m  748 S  2.7  0.1  55:44.67 mfsmount

This is mfsmount on a server where only write traffic happens:

root       0 -19  298m  39m  528 S  4.0  2.0   2017:43 mfsmount

On another machine with a mix of read and write:

root       6 -19  364m  12m  492 S  0.0  0.2  57:15.53 mfsmount

But, yes. We will have to see how we can juggle hardware to get the best 
performance within the other constraints we have.

Robert

On 7/4/11 5:58 PM, Ricardo J. Barberis wrote:
> El Lunes 04 Julio 2011, Robert Sandilands escribió:
>> We plan on adding more chunkservers as we move content from traditional
>> file systems to MFS. A dedicated master may be some time away. Getting a
>> machine with 64+ GB of RAM is not always easy to get past the budget
>> monsters.
> If the problem is RAM, you can take some from your chunkservers, as they don't
> use it much (only for disk cache I would guess).
>
> Or, once you add another chunkserver you might free the master disks and keep
> it as master only.
>
> I don't have so many files (600.000) but my chunkservers have 2 or 4 GB and
> are only using ~200 MB and my master is using 580 MB from a total of 4 GB.
>
> The rest of the memory is all used for disk cache and buffers, at least
> acording to "free -m".
>
> Regards,