On Thursday June 22, [EMAIL PROTECTED] wrote: > > > Thanks Neil for your quick reply. Would it be possible to elaborate a > bit on the problem and the solution? I guess I won't be on 2.6.18 for > some time... >
When an array has been idle (no writes) for a short time (20 or 200 ms, depending on which kernel you are running) the array is flagged as 'clean'. so that a crash/power failure at that point will not require a full resync. The 'clean' flag is stored on all superblocks, including the spares. So this causes writes to all devices when there is changes to activity status. Even fairly quite filesystems see occasional updates (updating atime on files, or such syncing the journal), and that causes all devices to be touched. Fix 1/ don't set the 'dirty' flag on spares - there really is no need. However whenever the dirty bit is changed, the 'events' count is updated, so just doing the above will cause the spares to get way behind the main devices in their 'events' count so they will no longer be treated as part of the array. So 2/ When clearing the dirty flag (and nothing else has happened), decrement the events count rather than increment it. Together, these mean that simple dirty/clean transitions do not touch the spares. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
