hadoop-hdfs-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Allen Wittenauer"...@apache.org>
Subject Re: Supervisely, RAID0 provides best io performance whereas no RAID the worst
Date Mon, 01 Aug 2016 06:29:57 GMT

On 2016-07-30 20:12 (-0700), Shady Xu <shadyxu@gmail.com> wrote: 
> Thanks Andrew, I know about the disk failure risk and that it's one of the
> reasons why we should use JBOD. But JBOD provides worse performance than
> RAID 0. 

It's not about failure: it's about speed.  RAID0 performance will drop like a rock if any
one disk in the set is slow. When all the drives are performing at peak, yes, it's definitely
faster.  But over time, drive speed will decline (sometimes to half speed or less!) usually
prior to a failure. This failure may take a while, so in the mean time your cluster is getting
slower ... and slower ... and slower ...

As a result, JBOD will be significantly faster over the _lifetime_ of the disks vs. a comparison
made _today_.

To unsubscribe, e-mail: user-unsubscribe@hadoop.apache.org
For additional commands, e-mail: user-help@hadoop.apache.org

View raw message