Am Donnerstag, 17. Juni 2010 22:54:25 schrieb Andrew Deason: > On Thu, 17 Jun 2010 22:01:08 +0200 > > Christof Hanke <christof.ha...@rzg.mpg.de> wrote: > > Am Donnerstag, 17. Juni 2010 21:30:23 schrieb Andrew Deason: > > > And in particular, NTFS and other journalled filesystems have the > > > advantage of a journal, and probably lots of other similarly helpful > > > things. Guess what we do not have. > > > > Right, this is actually Hartmut's point. We have user-volumes spread > > out over a few fileservers, so in each partition of such a server > > there are hundreds of user home-volumes. It is very painful for the > > admin and his phone, if these are not back up quickly. Being user-home > > volumes they are active, so DAFS does _not_ help here at all. That's > > why we take the risk of some minor corruptions rather than knowing > > that some hundred people cannot work at all (or simulation-jobs crash > > or what not). > > I am not the one you need to convince about this line of thinking, but > I'm not sure I agree about DAFS not being a help here at all. When you > say the volumes are "active", how active is "active"? DAFS gives you > some configuration knobs which allow you to specify how often inactive > volumes become detached. The default is 2 hours, but you could possibly > set it much lower than that. > I know I don't have to convince you. Well, these are Home-Volumes. I do hope that my users touch their home more often than once in 2 hours.
> That has other performance implications and I'm not necessarily > recommending doing that, but it's something to think about. > > > Thus, there is no real alternative to us there yet. Unless DAFS > > salvages some hundred volumes in parallel rather than one after the > > other. Does it do that ? This might alleviate the problem. > > You can salvage multiple volumes on a partition at once, but not > hundreds, and not with the speed you want yet. There is some > mostly-complete code to allow a much higher number of salvages to occur > at once, but I'm pretty sure that will not be merged for the 1.6 > release. I'm not sure about subsequent releases in the 1.6 series, but > it will probably be in at least 1.10 the way things are going now. But > since 1.10 is the earliest possible time I've heard that fast-restart > will be removed, perhaps that's not so bad for you. > Let's see. we have plenty of out-of-tree patches anyway, but I seek to reduce their number. > And as has been mentioned elsewhere in the thread, you need to wait for > the VG hierarchy summary scan to complete, no matter how fast salvaging > is or how many you do in parallel. That involves reading the headers of > all volumes on the partition, so it's not fast (but it is very fast if > you're comparing it to the recovery time of a 1.4 unclean shutdown) That's ok, I guess. _______________________________________________ OpenAFS-info mailing list OpenAFS-info@openafs.org https://lists.openafs.org/mailman/listinfo/openafs-info