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From "ssivikt@gmail.com" <ssiv...@gmail.com>
Subject Re: Possible to adjust tokens on a vnode cluster?
Date Thu, 21 Jan 2016 13:11:55 GMT
Hello John!

I'm just wonder how often one of your cluster nodes 
failed/crashed/go_down or meets disks crashing? Looking for some sort of 
probability of hardware failure..

Thank you.

On 01/19/2016 09:21 PM, John Sumsion wrote:
>
> I have a 24 node cluster, with vnodes set to 256.
>
>
> 'nodetool status <ks>' looks like this for our keyspace:
>
>
> UN  <ip01>    588.23 GB  256     11.0% 
> 0c8708a7-b962-4fc9-996c-617da642d9ee  1a
> UN  <ip02>    601.33 GB  256     11.3% 
> 5ef60730-0b01-4a8b-a578-d828cdf78a1f  1b
> UN  <ip03>    613.02 GB  256     11.5% 
> dddc78b1-7dc2-4e9f-8e8a-1b52595aa0e3  1a
> UN  <ip04>    620.76 GB  256     11.7% 
> 87ac93ff-dc8e-4cd5-842c-0389ce016d70  1b
> UN  <ip05>    631.81 GB  256     11.9% 
> 8e1416aa-3e75-4ab5-a2a6-49d26f514115  1d
> UN  <ip06>    634.65 GB  256     11.9% 
> 3c97f722-16f5-455c-8f58-71c07ad93d25  1b
> UN  <ip07>    634.79 GB  256     11.9% 
> 3e3d41bd-d6e8-4a7e-aee2-7ea16b1dadb9  1d
> UN  <ip08>    637.05 GB  256     12.0% 
> 2f26f19a-c88f-4cbe-b865-155c0b66bff0  1b
> UN  <ip09>    637.83 GB  256     12.0% 
> 6385e073-5b48-49b3-a85b-e7511fa8b3a0  1a
> UN  <ip10>    638.05 GB  256     12.1% 
> 382681e5-c060-4594-ae2a-062a324c12d4  1d
> UN  <ip11>    660.22 GB  256     12.4% 
> ea6aad23-7d93-4989-8898-7505df51298f  1d
> UN  <ip12>    674.98 GB  256     12.6% 
> 7d372371-c23f-4235-9e3c-cf030fb52ab3  1a
> UN  <ip13>    676.22 GB  256     12.7% 
> 41c4cb98-91ae-43a6-9bc4-11aa6106faad  1d
> UN  <ip14>    680.15 GB  256     12.7% 
> 65ac3aef-8a9b-423d-83fb-ed8e41f88ccc  1a
> UN  <ip15>    681.35 GB  256     12.8% 
> e38efc6a-e7eb-4d8e-9069-a0b099bea96e  1d
> UN  <ip16>    693.19 GB  256     13.0% 
> 2b9a5d3e-8529-47fe-8d2c-13553a8df91f  1b
> UN  <ip17>    696.92 GB  256     13.0% 
> 46382cd1-402c-4200-858c-100dade03fc5  1d
> UN  <ip18>    698.17 GB  256     13.1% 
> a68107e7-8e1a-469e-8dd1-e2d87445fd47  1b
> UN  <ip19>    698.92 GB  256     13.1% 
> 662338a7-1f5c-4eaa-926e-9e9fda926504  1a
> UN  <ip20>    699.26 GB  256     13.1% 
> e7c15c56-80e6-4961-9cd9-c1302fbf2026  1a
> UN  <ip21>    702.98 GB  256     13.2% 
> 461baba0-60f3-423a-a5cf-e0c482da2dbf  1b
> UN  <ip22>    710.27 GB  256     13.3% 
> ffa9700d-50ef-4b23-92d9-18f8029c8cd6  1d
> UN  <ip23>    740.63 GB  256     13.8% 
> d9c6e2a1-2193-4f32-8426-3bd7ad8bf679  1a
> UN  <ip24>    744.12 GB  256     13.9% 
> ff841094-7624-4dc5-b480-f39138b7f17c  1b
>
> First, the difference in disk usage between 588G (lowest) and 744G 
> (highest) is significant - at 156G.  I'm sure it's probably a weird 
> pattern in our partition keys, but we can't predict that until we get 
> the data loaded.
>
>
> Maybe someone will advise against using vnodes altogether, but we need 
> to be able to add 3 nodes for extra capacity and would like not to 
> have to rewrite the vnode token assignment code in order to figure out 
> a rack-safe token reassignment.
>
>
> Given the above, is there any way to manually adjust tokens (while 
> still using vnodes) so that we can balance the disk usage out?  If so, 
> is there an easy way to do that in a rack-safe manner?
>
>
> Thanks,
>
> John...
>

-- 
Thanks,
Serj


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