Jeff Jirsa

> On Dec 22, 2017, at 2:01 AM, Vincent Smit <> wrote:
> Hi,
> I am currently involved in a project to scale-up an existing Windows 
> Cassandra cluster because we are planning to migrate large amounts of 
> historic data. However, I am a bit skeptical to keep using Windows for the 
> nodes. I have done some research about Cassandra on Windows and found some 
> releasenotes that there is official support for Windows since 2.2.x. but 
> since then I cannot find any mention of Windows support.
> I was wondering what the current state of Cassandra is on windows?

It probably mostly works, but I’m not aware of any large users or active 
testing using any OS other than Linux. I suspect (wild ass guess) most people 
using cassandra on windows have it running on local developer machines, not 
prod clusters. 

> Second question; I we do decide to switch to Linux, would the following 
> migration path work? It is vital that there is no downtime for the client 
> application..

I’m going to guess below, but it’s a guess, and you should practice this before 
you do it.

> 1. Set-up a new Linux cluster and have our incoming data stream into the 
> existing Windows and new Linux cluster.
> 2. Use the SSTableloader to stream the existing SSTables to the Linux cluster.
> 3. Switch the endpoint of the application to the new Linux cluster.

This double writing probably works. It may also be possible to have a mixed-os 
cluster - I would personally try to add a Linux node (or data center)  to a 
windows cluster, and then remove a windows node, and repeat until it’s all 
Linux. I’ve never done that, but no reason to believe it wouldn’t work.

> Would this work even if we have incoming live data that share the 
> partitionkeys with the data that needs to be migrated? Could the timestamps 
> or tombstones cause a problem?

It should be fine. Timestamps and tombstones both live in the sstable, and will 
transfer across, but you need to set gc grace seconds artificially high during 
the migration to make sure no tombstones get cleaned up on the Linux cluster 
until the transfer back from windows is complete. 

Good luck, do let us know if it works (or doesn’t work)

> Met vriendelijke groeten / Best regards / Mit freundlichen Grüssen,
> Vincent Smit
> Energy Consultant
> MOB      +31 (0)6 2141 5772
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