Re: Combining MON & OSD Nodes

[Shane Gibson <Shane_Gibson@xxxxxxxxxxxx>]

For a small deployment this might be ok - but as mentioned, mon logging might be an issue.  Consider the following:

  * disk resources for mon logging (maybe dedicate a disk to logging, to avoid disk IO contention for OSDs)

  * CPU resources, some Filesystem types for OSDs can eat a lot of CPU (that' good, they're doing hard work, your using those resources to gain performance!!)

  * consider memory pressure of both mons and OSDs - Filesystem cache in memory is a good thing, are you going to be impacting that w/ comingling mons? 

If you have fairly decent machines with more cores/HTs than OSD disks, you probably don't have a huge CPU issue to worry about (...probably...).  

~~shane 

On 6/25/15, 9:23 AM, "ceph-users on behalf of Quentin Hartman" <ceph-users-bounces@xxxxxxxxxxxxxx on behalf of qhartman@xxxxxxxxxxxxxxxxxxx> wrote:

The biggest downside that I've found is the log volume that mons create eats a lot of io. I was running mons on my OSDs previously, but in my current dpeloyment I've moved them to other hardware and noticed a perceptible load reduction on those nodes that were formerly running mons.

QH

On Thu, Jun 25, 2015 at 10:21 AM, Lazuardi Nasution <mrxlazuardin@xxxxxxxxx> wrote:

Hi,

I'm looking for pros and cons of combining MON and OSD functionality on the same nodes. Mostly recommended configuration is to have dedicated, odd number MON nodes. What I'm thinking is more like single node deployment but consist more than one node, if we have 3 nodes we have 3 MONs with 3 OSDs. Since MON will only consume small resources, I think MON load will not degrade OSD performance significantly. If we have odd number of nodes, we can still maintain the quorum of MON with this way. Any idea?

Best regards,

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