Neil Brown wrote: > On Saturday March 22, jpiszcz@xxxxxxxxxxxxxxx wrote: >> >> On Sat, 22 Mar 2008, Peter Rabbitson wrote: >> >>> Robin Hill wrote: >>>> On Fri Mar 21, 2008 at 07:01:43PM -0400, Bill Davidsen wrote: >>>> >>>>> Peter Rabbitson wrote: >>> UUID : b6a11a74:8b069a29:6e26228f:2ab99bd0 (local to host Arzamas) >>> Events : 0.183270 >>> >>> As you can see it is pretty old, and does not have many events to speak of. >> What do the 'Events' actually represent and what do they mean for RAID0, >> RAID1, RAID5 etc? > > An 'event' is one of: > switch from 'active' to 'clean' > switch from 'clean' to 'active' > device fails > device is added > spare replaces a failed device after a rebuild > > I think that it all. > > None of these are meaningful for RAID0, so the 'events' counter on > RAID0 should be stable. > > Unfortunately, the number looks like a decimal but isn't. > It is a 64bit number. We print out the top 32 bits, then the bottom > 32 bits. I don't remember why. Maybe I'll 'fix' it. > >> How are they calculated? > > events = events + 1; > > > Feel free to merge this text into the wiki. Thanks Neil :) http://linux-raid.osdl.org/index.php?title=Event I also added: == What are they for? == When an array is assembled, all the disks should have the same number of events. If they don't then something odd happened. eg: If one drive fails then the remaining drives have their event counter incremented. When the array is re-assembled the failed drive has a different event count and is not included in the assembly. This lead me to ponder: How/when are events reset to equality? I wrote: The event count on a drive is set to zero on creation and reset to the majority on a resync or a forced assembly. Is that right? David -- 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
