Force to redistribute tablets among available tservers

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Force to redistribute tablets among available tservers

Maxim Kolchin
Hi all,

Imagine a cluster with one tserver which hosts N tablets. At some point, I decide to add another tserver to the cluster. Is it possible force Accumulo to move (redistribute) part of tablets to the new tserver? If it so, how to do that? I tried to google and to look at the list of Accumulo shell commands, but without any success.

Thank you in advance!
Maxim Kolchin

E-mail: [hidden email]
Homepage: http://kolchinmax.ru
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Re: Force to redistribute tablets among available tservers

Jeff Kubina
Maxim, I don't think there is a command to force that since the master's default balancer will do that automatically for all the tablets. You can speed the process up for an individual table by taking it offline and then online; the table's tablets will be balanced across the tservers when it comes back online.

-- 
Jeff Kubina
410-988-4436


On Wed, Jul 4, 2018 at 7:23 AM, Maxim Kolchin <[hidden email]> wrote:
Hi all,

Imagine a cluster with one tserver which hosts N tablets. At some point, I decide to add another tserver to the cluster. Is it possible force Accumulo to move (redistribute) part of tablets to the new tserver? If it so, how to do that? I tried to google and to look at the list of Accumulo shell commands, but without any success.

Thank you in advance!
Maxim Kolchin

E-mail: [hidden email]
Homepage: http://kolchinmax.ru

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Re: Force to redistribute tablets among available tservers

Maxim Kolchin
Hi Jeff,

> an individual table by taking it offline and then online

Thank you! I'll try that. But it means that it's not possible to do while the table is being used, is it correct?

Is it possible to somehow adapt the default balancer's behaviour, so that it would redistribute tablets after N secs (or mins) a new tserver being online?

Maxim

On Wed, Jul 4, 2018 at 5:05 PM Jeff Kubina <[hidden email]> wrote:
Maxim, I don't think there is a command to force that since the master's default balancer will do that automatically for all the tablets. You can speed the process up for an individual table by taking it offline and then online; the table's tablets will be balanced across the tservers when it comes back online.

-- 
Jeff Kubina
410-988-4436


On Wed, Jul 4, 2018 at 7:23 AM, Maxim Kolchin <[hidden email]> wrote:
Hi all,

Imagine a cluster with one tserver which hosts N tablets. At some point, I decide to add another tserver to the cluster. Is it possible force Accumulo to move (redistribute) part of tablets to the new tserver? If it so, how to do that? I tried to google and to look at the list of Accumulo shell commands, but without any success.

Thank you in advance!
Maxim Kolchin

E-mail: [hidden email]
Homepage: http://kolchinmax.ru

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Re: Force to redistribute tablets among available tservers

Jeff Kubina
Correct, the table can't be in use while taking it offline and then online.

The default balancer is called about every minute. You should be able to see that in the master's logs. 

It is certainly possible, but not easy, to adapt the default balancer to redistribute tablets more quickly.

-- 
Jeff Kubina
410-988-4436


On Thu, Jul 5, 2018 at 5:45 AM, Maxim Kolchin <[hidden email]> wrote:
Hi Jeff,

> an individual table by taking it offline and then online

Thank you! I'll try that. But it means that it's not possible to do while the table is being used, is it correct?

Is it possible to somehow adapt the default balancer's behaviour, so that it would redistribute tablets after N secs (or mins) a new tserver being online?

Maxim

On Wed, Jul 4, 2018 at 5:05 PM Jeff Kubina <[hidden email]> wrote:
Maxim, I don't think there is a command to force that since the master's default balancer will do that automatically for all the tablets. You can speed the process up for an individual table by taking it offline and then online; the table's tablets will be balanced across the tservers when it comes back online.

-- 
Jeff Kubina
410-988-4436


On Wed, Jul 4, 2018 at 7:23 AM, Maxim Kolchin <[hidden email]> wrote:
Hi all,

Imagine a cluster with one tserver which hosts N tablets. At some point, I decide to add another tserver to the cluster. Is it possible force Accumulo to move (redistribute) part of tablets to the new tserver? If it so, how to do that? I tried to google and to look at the list of Accumulo shell commands, but without any success.

Thank you in advance!
Maxim Kolchin

E-mail: [hidden email]
Homepage: http://kolchinmax.ru