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From aaron morton <>
Subject Re: Damaged commit log disk causes Cassandra client to get stuck
Date Sun, 31 Jul 2011 21:19:16 GMT
A couple of timeouts should have kicked in. 

First the rpc_timeout on the server side should have kicked in and given the client a (thrift)
TimedOutException. Secondly a client side socket timeout should be set so the client will
timeout the socket. Did either of these appear in the client side logs?

In response to either of those my guess would be that hector would cycle the connection. (I've
not checked this.)

How did the disk fail ? Was their anything in the server logs ? 

Some background about handling disk fails


Aaron Morton
Freelance Cassandra Developer

On 1 Aug 2011, at 08:13, Lior Golan wrote:

> In one of our test clusters we had a damaged commit log disks in one of the nodes.
> We have replication factor = 2 in this cluster, and write with consistency level = ONE.
So we expected writes will not be affected by such an issue. But what actually happened is
that the client that was writing with CL.ONE got stuck. The client could resume writing when
we stopped the server with the faulty disk (so this is another indication it's not a replication
factor or consistency level issue).
> We are running Cassandra 0.7.6, and the client we're using is Hector.
> Can anyone explain what happened here? Why the client got stuck when the commit log disk
on one of the servers damaged (and could resume writing if we actually took off that server)?

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