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Vertica consuming temporarily disk space

  • January 5, 2017
  • 3 replies
  • 10 views

ckotsidimos
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Hi there,

I have seen vertica 7.1 in my installation randomly in a node consuming all the space and then releasing it. I have managed to find a folder in teh data path that grows and then it shrinks again. the name of the folder is MgO_26239203. 

Have you ever seen this? 

I would appreciate any help on this

3 replies

K_Krutiy
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  • Participating Frequently
  • January 14, 2017

Vertica stores data in immutable ROS containers.
To keep performance in good shape you need to have low number of ROS containers.

Vertica regularly checks state of ROS containers and periodically merges multiple smaller ROS containers
into single larger ROS container. Those operations need to use space temporarily.

Similar things happen when you do PURGE, projection refresh or rebalance your cluster.

For those reasons Vertica recommends to have at least 50% of free space.

Also additional space will be needed when you do backups. Hard link backups will create links to all files.
This may consume extra space until the backup is removed.


So in general space fluctuations is expected and in most cases considered normal.


tharanga
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  • February 2, 2017

+1 K_Krutiy.

MgO_* folders are created temporarily for the TM mergeout process.


ckotsidimos
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  • April 24, 2017

Thank you very much