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From Ioannis Zafiropoulos <john...@gmail.com>
Subject Re: Removing a disk from JBOD configuration
Date Mon, 31 Jul 2017 13:41:46 GMT
Thank you Jeff for your answer,

I use RF=3 and our client connect always with QUORUM. So I guess I will be
alright after a repair (?)
Follow up questions,
- It seems that the risks you describing would be the same as if I had
replaced the drive with an new fresh one and run repair, is that correct?
- can I do the reverse procedure in the future, that is, to add a new drive
with the same procedure I described?

Thanks,
John



On Mon, Jul 31, 2017 at 5:42 AM, Jeff Jirsa <jjirsa@gmail.com> wrote:

> 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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