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HDFS >> mail # user >> HDFS drive, partition best practice


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Re: HDFS drive, partition best practice
On Tue, Feb 8, 2011 at 12:09 PM, Allen Wittenauer
<[EMAIL PROTECTED]>wrote:

>
> On Feb 8, 2011, at 11:33 AM, Adam Phelps wrote:
>
> > On 2/7/11 2:06 PM, Jonathan Disher wrote:
> >> Currently I have a 48 node cluster using Dell R710's with 12 disks - two
> >> 250GB SATA drives in RAID1 for OS, and ten 1TB SATA disks as a JBOD
> >> (mounted on /data/0 through /data/9) and listed separately in
> >> hdfs-site.xml. It works... mostly. The big issues you will encounter is
> >> losing a disk - the DataNode process will crash, and if you comment out
> >> the affected drive, when you replace it you will have 9 disks full to N%
> >> and one empty disk.
> >
> > If DataNode is going down after a single disk failure then you probably
> haven't set dfs.datanode.failed.volumes.tolerated in hdfs-site.xml.  You can
> up that number to allow DataNode to tolerate dead drives.
>
> a) only if you have a version that supports it
>
> b) that only protects you on the DN side.  The TT is, AFAIK, still
> susceptible to drive failures.
c) And it only works when the drive fails on read (HDFS-457), not on write
(HDFS-1273).