On 11/12/2013 03:52 AM, NeilBrown wrote:

On Mon, 11 Nov 2013 02:56:37 -0600 Stan Hoeppner [off-list ref]
wrote:

quoted

On 11/11/2013 1:44 AM, Mikael Abrahamsson wrote:

quoted

I believe this has been discussed before, but I would like to bring it
up again.

I would like to see mdadm recommend RAID6 over RAID6 when using
component drives that are 500GB or larger and ask if the user is really
sure about using RAID5, plus a pointer to a webpage on the wiki
informing the user about the trouble with RAID5 on large volumes with
consumer or prosumer drives.

I am willing to contribute text to the webpage being pointed to.

Wikis change to regularly, too easily.  Networks can be down at times,
often the worst times.  See Murphy's Law.

It would be better to put this information in mdadm(8) and refer the
user there.

.. or in md(4) maybe.

If anyone wants to run with this and send me a patch (for code and
documentation) I would be very likely to apply it.

NeilBrown

That issue (RAID5 going fully down during resync of degraded array if 
read errors occur) hasn't been addressed by the badblocks log feature 
available in later kernels and mdadm ?
Yet, it is not clear to me if the fetaure is fully implemented and 
operational.

Regards
Giovanni