[jira] [Commented] (KUDU-2117) Spread metadata across multiple data directories

["Andrew Wong (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KUDU-2117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16144142#comment-16144142 ] 

Andrew Wong commented on KUDU-2117:
-----------------------------------

See Todd's comment:
bq. More than just switching to the WAL dir, we may want to allow striping across all of the disks, given that many users don't have SSDs. Striping across 12 spinning disks gives a 12x speedup vs trying to fit them all into one.

> Spread metadata across multiple data directories
> ------------------------------------------------
>
>                 Key: KUDU-2117
>                 URL: https://issues.apache.org/jira/browse/KUDU-2117
>             Project: Kudu
>          Issue Type: Bug
>          Components: fs, tablet, tserver
>    Affects Versions: 1.6.0
>            Reporter: Andrew Wong
>            Assignee: Andrew Wong
>             Fix For: 1.6.0
>
>
> Tablet metadata and consensus metadata are placed in the first configured data directory. This is an issue, as every write to these metadata incurs an fsync and this stresses the first disk considerably more than the others
> One way around this is to spread metadata across multiple data directories. A natural choice would be to place them in a directory within the tablet's disk group. In this way, the data/metadata can be completely localized to the disk group, which has the added benefit of making the risk of disk failures easier to assess per tablet.



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