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Subject: Re: OOM when Adding host 
From: rock zhang <rock@alohar.com>
In-Reply-To: <796B4E63-B95B-477D-99F2-2FC66FB252C4@alohar.com>
Date: Mon, 10 Aug 2015 09:59:43 -0700
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Message-Id: <54804B16-1BF4-4591-BF6A-D4A3BA28D33F@alohar.com>
References: <796B4E63-B95B-477D-99F2-2FC66FB252C4@alohar.com>
To: "user@cassandra.apache.org" <user@cassandra.apache.org>

My Cassandra version is 2.1.4.

Thanks
Rock=20

On Aug 10, 2015, at 9:52 AM, rock zhang <rock@alohar.com> wrote:

> Hi All,
>=20
> Currently i have three hosts. The data is not balanced, one is 79G, =
another two have 300GB. When I adding a new host, firstly I got "too =
many open files" error, then i changed file open limit from 100,000 to =
1, 000, 000. Then I got OOM error.
>=20
> Should I change the limits to 20,0000 instead of 1M?  My memory is =
33G, i am using EC2 c2*2xlarge.  Ideally even if the data is large, just =
slower, should not OOM, don't understand why .
>=20
> I actually got this error pretty often. I guess the reason is because =
my data is pretty large?  If cassandra try to split the data evenly on =
all host, then Cassandra need to copy around 200GB to the new host.=20
>=20
> =46rom my experience, An alternative way to solve this is add new host =
as seed, do not use "Add host", then data would be move, so so OOM. But =
not sure data will be lost or cannot be located.=20
>=20
> Thanks
> Rock=20
>=20