Re: Should the disk write cache be disabled?

["Da Chun" <ngugc@xxxxxx>]

Do you mean the "write barrier"?

So all ceph disk partitions are mounted with "barrier=1"?

------------------ Original ------------------

From:  "Gregory Farnum"<greg@xxxxxxxxxxx>;

Date:  Wed, Jul 17, 2013 00:29 AM

To:  "Da Chun"<ngugc@xxxxxx>;

Cc:  "ceph-users"<ceph-users@xxxxxxxxxxxxxx>;

Subject:  Re: [ceph-users] Should the disk write cache be disabled?

Just old kernels, as they didn't correctly provide all the barriers
and other ordering constraints necessary for the write cache to be
used safely.
-Greg
Software Engineer #42 @ http://inktank.com | http://ceph.com


On Tue, Jul 16, 2013 at 9:20 AM, Da Chun <ngugc@xxxxxx> wrote:
> In this doc,
> http://ceph.com/docs/master/rados/configuration/filesystem-recommendations/
>
> It says,
>
> Ceph aims for data safety, which means that when the Ceph Client receives
> notice that data was written to a storage drive, that data was actually
> written to the storage drive. For old kernels (<2.6.33), disable the write
> cache if the journal is on a raw drive. Newer kernels should work fine.
>
> Use hdparm to disable write caching on the hard disk:
>
> sudo hdparm -W 0 /dev/hda
>
> Does it mean the disk write cache should be always disabled for ceph, or
> just when using the old kernel (<2.6.33)?
>
> Thanks for your time!
>
>
> _______________________________________________
> ceph-users mailing list
> ceph-users@xxxxxxxxxxxxxx
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>

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