Hello, I am trying to make the mds to initiate some action on the stripe objects of one file. For example, I can read the lov_mds_md/lov_stripe_md extended attribute of a file inode in the mds. What I want to do is to let the mds to send an rpc message to the OSTs hold these stripe objects to do some actions. What I cannot solve is how the mds can derive the identity, i.e., uuid, of the OSTs. The information in the md (loi_ost_idx or l_ost_idx) is the "OST index in LOV (lov_tgt_desc->tgts)". My understanding is that the lov obd is running on the client node instead of mds, so I cannot figure out how the mds can translate such index number to the uuid of OSTs. Can anyone give me a suggestion on this or correct me if my understanding is wrong. In addition, I am wondering how the files created by the "lstripe" utility is accessed as there is no lov obd for them. For example, client A creates a file foo using lstripe. Another client B should be able to access file foo but how client B manages to get the uuid of OSTs holding stripes of foo? Any suggestion or clarification is highly appreciated! Dingshan