dm-devel-bounces@xxxxxxxxxx wrote on 13.04.2007 11:49:07: > > 1. Is recovery here really necessary ? > > Every time when a bio is written to a mirrred target, mirror driver > will queue > this io to the write bio_list whthin the mirror_set, finally a kcopyd will be > invoke to write this bio to all mirrored device. Is the flow correct? > AFAIK, thats wrong. Write creates and submits one write bio for each mirror target. Kcopyd won't be used, except for recovery (currently startup only if I remember correctly). > But... there are nothing doing in the write callback function > (write_callback).... right ? > So in the current version, we won't have any regions that is needed > to be recovered. > Starting any I/O within a region will mark this as dirty. If all I/O on a region completed sucessfully it will be set in-sync again. Haven't looked at that lately but it was a bit hidden since write_callback didn't do all the work. Parts of it were done in the common end_io function of the target. > ---------------------------------------------------------------- > > 2. Should we put all read action into the read bio_list of the mirror_set ? > > In mirror_map.... should we put all read requests into the read > bio_list of the > mirror_set after check the return value from log->type->in_sync(), since > do_read() method does the same thing and it will be invoke when a do_work > is invoke? Or shoulwe d move all read actions including the checking > (in mirror_map) to the do_read() function ? > > ---------------------------------------------------------------- > IMHO better move all to the read bio_list. So the mapping completes sooner and the balancing and possible retries could be done in one place. Regards, Stefan -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
