Re: mon disk access pattern

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 15.06.2012 13:34, schrieb Mark Nelson:
> On 06/15/2012 04:51 AM, Wido den Hollander wrote:
>> Hi,
>>
>> On 15-06-12 07:52, Stefan Priebe - Profihost AG wrote:
>>> Hello list,
>>>
>>> i read somewhere that the mon has "special" disk access patterns - even
>>> though it does not write much data.
>>
>> "special"? Where did you read that? The monitor has about 1 ~ 2GB of
>> storage.
>>
>> So if your monitor has something like 4GB ~ 8GB of RAM, your kernel
>> should cache almost all your monitor data.
>>
>
> I think at some point someone mentioned to me that the mon can cause a
> lot of syncs, so running them on the OSDs without syncfs might be
> detrimental. For the majority of our internal performance testing I've
> kept them off the OSDs just to be sure.

My main idea behind that was what type of disk i need for a performant 
mon system. SATA, SAS, SSD? Raid?

Stefan