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From Vladimir Yudovin <vla...@winguzone.com>
Subject Re: Adding disk capacity to a running node
Date Mon, 17 Oct 2016 19:01:40 GMT
But after such restart node should be joined to cluster again and restore data, right?



Best regards, Vladimir Yudovin, 

Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.






---- On Mon, 17 Oct 2016 14:55:49 -0400Jonathan Haddad &lt;jon@jonhaddad.com&gt; wrote
----




Vladimir,



*Most* people are running Cassandra are doing so using ephemeral disks.  Instances are not
arbitrarily moved to different hosts.  Yes, instances can be shut down, but that's why you
distribute across AZs.  




On Mon, Oct 17, 2016 at 11:48 AM Vladimir Yudovin &lt;vladyu@winguzone.com&gt; wrote:







It's extremely unreliable to use ephemeral (local) disks. Even if you don't stop instance
by yourself, it can be restarted on different server in case of some hardware failure or AWS
initiated update. So all node data will be lost.





Best regards, Vladimir Yudovin, 

Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.







---- On Mon, 17 Oct 2016 14:45:00 -0400Seth Edwards &lt;seth@pubnub.com&gt; wrote
----







These are i2.2xlarge instances so the disks currently configured as ephemeral dedicated disks.




On Mon, Oct 17, 2016 at 11:34 AM, Laing, Michael &lt;michael.laing@nytimes.com&gt;
wrote:






You could just expand the size of your ebs volume and extend the file system. No data is lost
- assuming you are running Linux.





On Monday, October 17, 2016, Seth Edwards &lt;seth@pubnub.com&gt; wrote:

We're running 2.0.16. We're migrating to a new data model but we've had an unexpected increase
in write traffic that has caused us some capacity issues when we encounter compactions. Our
old data model is on STCS. We'd like to add another ebs volume (we're on aws) to our JBOD
config and hopefully avoid any situation where we run out of disk space during a large compaction.
It appears that the behavior we are hoping to get is actually undesirable and removed in 3.2.
It still might be an option for us until we can finish the migration. 



I'm not familiar with LVM so it may be a bit risky to try at this point. 




On Mon, Oct 17, 2016 at 9:42 AM, Yabin Meng &lt;yabinmeng@gmail.com&gt; wrote:

I assume you're talking about Cassandra JBOD (just a bunch of disk) setup because you do mention
it as adding it to the list of data directories. If this is the case, you may run into issues,
depending on your C* version. Check this out: http://www.datastax.com/dev/blog/improving-jbod.



Or another approach is to use LVM to manage multiple devices into a single mount point. If
you do so, from what Cassandra can see is just simply increased disk storage space and there
should should have no problem.



Hope this helps,



Yabin




On Mon, Oct 17, 2016 at 11:54 AM, Vladimir Yudovin &lt;vladyu@winguzone.com&gt; wrote:



Yes, Cassandra should keep percent of disk usage equal for all disk. Compaction process and
SSTable flushes will use new disk to distribute both new and existing data.



Best regards, Vladimir Yudovin, 

Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.





---- On Mon, 17 Oct 2016 11:43:27 -0400Seth Edwards &lt;seth@pubnub.com&gt; wrote
----




We have a few nodes that are running out of disk capacity at the moment and instead of adding
more nodes to the cluster, we would like to add another disk to the server and add it to the
list of data directories. My question, is, will Cassandra use the new disk for compactions
on sstables that already exist in the primary directory? 







Thanks!


























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