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Hy all, I am facing some high I/O on my Vertica Cluster recently and is not because of bad query or design is just because of high workload and the business has got a lot bigger and the last months and there are no resources to be added to the running cluster. With that said i am thinking of some strategies to improve the nodes performance such as :

  • alter the devices conf and use the noatime option(stops recording the last file access time when the file is just read).

  • thinking of removing the journaling or moving it to another device.

I would like to know the experts opinion on this matter as this would be my last resort to improve a bit my overall cluster performance.

thank you all

Up_One
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1 Answers1

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  1. Using the noatime mount option would be a good way to reduce the I/O traffic, especialy if you have lots of small files open. The kernel must update the i-node timestamp every second for every open file; this could add up to a considerable savings. You cannot use the noatime option if any application uses the file metadata to determine anything about the file. For example, building an application using make(1) would yield inconsistent results. But for an application like a database who just cares about the content of the files, noatime could be used.
  2. To journal or not to journal.. Much depends on the storage media for these files. Using a journal on an SSD device seems counterproductive. Using a journal on an intelligent SAN could possibly be disabled. This would depend on the characteristics of the SAN/NAS firmware so ask the storage admin. Moving the journal to another device or LUN could be a win if the cost of journal-to-file I/O is significantly faster than server-to-LUN traffic. Only your storage admin knows for sure.
Oldest Software Guy
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