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From Jeff Jirsa <jji...@gmail.com>
Subject Re: Removing a disk from JBOD configuration
Date Mon, 31 Jul 2017 09:42:32 GMT
It depends on what consistency level you use for reads/writes, and whether you do deletes

The real danger is that there may have been a tombstone on the drive the failed covering data
on the disks that remain, where the delete happened older than gc-grace - if you simple yank
the disk, that data will come back to life (it's also possible some data temporarily reverts
to a previous state for some queries, though the reversion can be fixed with nodetool repair,
the resurrection can't be undone). If you don't do deletes, this is not a problem. If there's
no danger to you if data comes back to life, then you're probably ok as well.

Cassandra-6696 dramatically lowers this risk , if you're using a new enough version of Cassandra



-- 
Jeff Jirsa


> On Jul 31, 2017, at 1:49 AM, Ioannis Zafiropoulos <johnzaf@gmail.com> wrote:
> 
> Hi All,
> 
> I have a 7 node cluster (Version 3.10) consisting of 5 disks each in JBOD. A few hours
ago I had a disk failure on a node. I am wondering if I can:
> 
> - stop Cassandra on that node
> - remove the disk, physically and from cassandra.yaml
> - start Cassandra on that node
> - run repair
> 
> I mean, is it necessary to replace a failed disk instead of just removing it? 
> (assuming that the remaining disks have enough free space)
> 
> Thank you for your help,
> John
> 

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