Dear all: Recently I am keeping tracing the device-mapper codes in kernel-2.6.20.1 There are still some question that confuse me... and I hope to change something in mirror driver... --------------------------------------------------------------- 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? 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. ---------------------------------------------------------------- 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 ? ---------------------------------------------------------------- Thanks for all... and please forgive my Chinese English..... is too poor.... (hopes some one understand what I am talking about in above...) regard.