Monitoring best practices

[Guy]

Are there any best practices for CB monitoring that I can reference? One of the metrics I'm trying to determine is the size of the working set (compared to total RAM available for bucket), but this data is split up into a number of separate items, eg. user data, replicas, metadata. I'm not 100% which of the metrics on the cbstats docs page (http://www.couchbase.com/docs/couchbase-manual-1.8/cbstats-all-bucket-info.html) relate to which of these items. ep_kv_size is apparently the user data size, but on the node stats page in the UI it lists ep_ht_memory, yet I can't find this value in the output of cbstats.

Can anyone tell me what I should look at to get the size of the working set?

Thanks,
Guy

[Frank Weigel]

This won't help you in sizing, but the easiest way to see whether your current working set fits into RAM is to look at the cache misses. They really should be below 1% for best performance. If you see cache misses frequently it means your working set isn't in RAM.

You can try and estimate the size of your working set based on average data size per user, plus meta data, replicas and knowedlege of what fraction of your users are typically active at the same time (or rather within a certain time window)

Frank

[Zeming Jin]

You should use vb_active_itm_memory.

[Guy]

Actually, does mem_used encapsulate all this? I see the value for it matches up with the 'In Use' value reported in the UI.

[Guy]

What are the units returned for these stats? AFAICT it's in bytes...but I get 3206887 for vb_active_itm_memory which equates to 3MB if they're bytes (which is much smaller than the UI-reported size of my bucket), or 3GB if they're KB, which is the total available size of my bucket.

[Guy]

Thanks Frank, I'll take a look at this.