Hi Robert, On Thu, Jun 21, 2012 at 04:58:33PM +0200, Robert Buchholz wrote: > Hello John, > > On Thursday, June 21, 2012 01:38:38 PM John Robinson wrote: > > On 20/06/2012 18:41, Robert Buchholz wrote: > > [...] > > > > > When repairing a full raid6 with no missing drives > > > (raid-devices=n+2), a single inconsistent data block could be > > > detected > > > > Yes, it could. See Neil Brown's blog post as to the many reasons why > > this isn't implemented: http://neil.brown.name/blog/20100211050355 > > Thank you for the pointer, I did not find the article before. > I agree with Neil's premise, this should not be run on a mounted raid as > changing data blocks can be a problem, and it should not be the default > for resync. However, as both Neil and commenters point out, this is a > valuable (offline) repair option. > > Do you know whether the "smart" algorithm or the API necessary to > construct a user space program are on the agenda? a tool is already available, albeit not too much advertised (my fault, basically). It is "raid6check" and it is included in "mdadm", at least in the source repository. It does *not* repair, but it will tell you which disk (if possible) and which stripe is incorrect from an non-degraded (of course) RAID-6. Any improvement to the code is very very welcome. Unfortunately I did not have time to follow up the thing, but a "repair" option might be interesting. bye, pg > > Cheers > > Robert -- piergiorgio -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
