Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> writes: > On Fri, 19 Oct 2007, Alberto Alonso wrote: > >> On Thu, 2007-10-18 at 17:26 +0200, Goswin von Brederlow wrote: >>> Mike Accetta <maccetta@xxxxxxxxxxxxxxxxxx> writes: >> >>> What I would like to see is a timeout driven fallback mechanism. If >>> one mirror does not return the requested data within a certain time >>> (say 1 second) then the request should be duplicated on the other >>> mirror. If the first mirror later unchokes then it remains in the >>> raid, if it fails it gets removed. But (at least reads) should not >>> have to wait for that process. >>> >>> Even better would be if some write delay could also be used. The still >>> working mirror would get an increase in its serial (so on reboot you >>> know one disk is newer). If the choking mirror unchokes then it can >>> write back all the delayed data and also increase its serial to >>> match. Otherwise it gets really failed. But you might have to use >>> bitmaps for this or the cache size would limit its usefullnes. >>> >>> MfG >>> Goswin >> >> I think a timeout on both: reads and writes is a must. Basically I >> believe that all problems that I've encountered issues using software >> raid would have been resolved by using a timeout within the md code. >> >> This will keep a server from crashing/hanging when the underlying >> driver doesn't properly handle hard drive problems. MD can be >> smarter than the "dumb" drivers. >> >> Just my thoughts though, as I've never got an answer as to whether or >> not md can implement its own timeouts. >> >> Alberto >> >> >> - >> 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 >> > > I have a question with re-mapping sectors, can software raid be as > efficient or good at remapping bad sectors as an external raid > controller for, e.g., raid 10 or raid5? > > Justin. Software raid makes no remapping of bad sectors at all. It assumes the disks will do sufficient remapping. MfG Goswin - 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
