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RE: Current data density limits with Open Source Cassandra


I request 1-2 TB of disk per node, depending on how large the data is estimated to be (for larger data, 2 TB). I have some dense nodes (4+ TB of disk available). They are harder to manage for repairs, bootstrapping, compaction, etc. because it takes so long to stream the data, etc. For the actual application, I have not seen a great impact based on the size of disk available.

 

 

Sean Durity

 

From: daemeon reiydelle [mailto:daemeonr@xxxxxxxxx]
Sent: Wednesday, February 08, 2017 10:56 PM
To: user@xxxxxxxxxxxxxxxxxxxx
Subject: Re: Current data density limits with Open Source Cassandra

 

your MMV. Think of that storage limit as fairly reasonable for active data likely to tombstone. Add more for older/historic data. Then think about time to recover a node.



.......

Daemeon C.M. Reiydelle
USA (+1) 415.501.0198
London (+44) (0) 20 8144 9872

 

On Wed, Feb 8, 2017 at 2:14 PM, Ben Slater <ben.slater@xxxxxxxxxxxxxxx> wrote:

The major issue we’ve seen with very high density (we generally say <2TB node is best) is manageability - if you need to replace a node or add node then restreaming data takes a *long* time and there we fairly high chance of a glitch in the universe meaning you have to start again before it’s done.

 

Also, if you’re uses STCS you can end up with gigantic compactions which also take a long time and can cause issues.

 

Heap limitations are mainly related to partition size rather than node density in my experience.

 

Cheers

Ben

 

On Thu, 9 Feb 2017 at 08:20 Hannu Kröger <hkroger@xxxxxxxxx> wrote:

Hello,

Back in the day it was recommended that max disk density per node for Cassandra 1.2 was at around 3-5TB of uncompressed data.

IIRC it was mostly because of heap memory limitations? Now that off-heap support is there for certain data and 3.x has different data storage format, is that 3-5TB still a valid limit?

Does anyone have experience on running Cassandra with 3-5TB compressed data ?

Cheers,
Hannu

--

————————

Ben Slater

Chief Product Officer

Instaclustr: Cassandra + Spark - Managed | Consulting | Support

 




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