Does Membase (Couchbase) admin statistics have a metric for memory hits vs disk hits?

50 views
Skip to first unread message

Orit Alul

unread,
Mar 24, 2011, 11:06:18 AM3/24/11
to mem...@googlegroups.com
Hi,

I'd like to measure the memory hits ratio (related to the total amount of hits memory + disk).
Can you please recommend what would be the best way to do that?

Can you please explain what the following metrics measure?
hit_ratio
get_hits
get_misses (is it a cluster miss (key not found) or a cache miss?)


Thanks,
Orit


Perry Krug

unread,
Mar 24, 2011, 2:24:40 PM3/24/11
to mem...@googlegroups.com, Orit Alul
Orit, the Membase UI presents this information as the graph labeled "Cache miss ratio".

To determine it yourself, you will need to calculate it with ep_bg_fetched (how many items have been fetched from disk) versus get_hits (how many items were serviced by the system overall).

-'hit_ratio' is not something the server provides directly, it is usually computed by an external system by measuring get_hits versus cmd_gets but this refers to the hit_ratio of the cluster (key not found) as opposed to coming off of disk.
-'get_hits' are the same as memcached and refer to how many gets were serviced with a key that the system had
-'get_misses' are also the same as memcached and refer to how many gets were serviced with a "key not found".

Perry

Perry Krug
Solutions Architect
direct: 831-824-4123
emailpe...@couchbase.com

Anton Mostovoy

unread,
Dec 20, 2012, 12:50:09 PM12/20/12
to mem...@googlegroups.com, Orit Alul
Perry, could you please clarify why "'hit_ratio' is not something the server provides directly, it is usually computed by an external system by measuring get_hits versus cmd_gets". Is it just about possible timeouts that could cause the client to see more misses?
So, is the existing hit_ratio metric calculated by get_hits/(gets_hits+get_misses)?

Thanks!
Reply all
Reply to author
Forward
0 new messages