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From Brian Burruss <>
Subject OOM Exception
Date Wed, 16 Dec 2009 23:16:19 GMT
i'll put my question first:

- how can i determine how much RAM is required by cassandra?  (for normal operation and restarting

*** i've attached my storage-conf.xml

i've gotten several more OOM exceptions since i mentioned it a week or so ago.  i started
from a fresh database a couple days ago and have been adding 2k blocks of data keyed off a
random integer at the rate of about 400/sec.  i have a 2 node cluster, RF=2, Consistency for
read/write is ONE.  there are ~70,420,082 2k blocks of data in the database.

i used the default memory setup of Xmx1G when i started a couple days ago.  as the database
grew to ~180G (reported by unix du command) both servers OOM'ed at about the same time, within
10 minutes of each other.  well needless to say, my cluster is dead.  so i upped the memory
to 3G and the servers tried to come back up, but one died again with OOM.

Before cleaning the disk and starting over a couple days ago, i played the game of "jack up
the RAM", but eventually i didn't want to up it anymore when i got to 5G.  the parameter,
SSTable.INDEX_INTERVAL, was discussed a few days ago that would change the number of "keys"
cached in memory, so i could modify that at the cost of read performance, but doing the math,
3G should be plenty of room.

it seems like startup requires more RAM than just normal running.

so this of course concerns me.

i have the hprof files from when the server initially crashed and when it crashed trying to
restart if anyone wants them

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