Alasdair, Jonathan: Any comments regarding kernel module vs implementing it entirely with in LVM to support this multi-log feature? Thanks, Malahal. malahal@xxxxxxxxxx [malahal@xxxxxxxxxx] wrote: > Takahiro Yasui [tyasui@xxxxxxxxxx] wrote: > > Hi Malahal, > > > A while back IBM posted a patch to LVM that constructs a log device with > > > a mirror and then creates the real mirror using such a mirrored log > > > device. I think this may solve your problem. It was completely written > > > in LVM and Stefan refreshed it to the latest LVM. > > > > Thank you for the comment and information. It seems that your > > approach seems to address my problem, too. Here I have a concern > > about write performance because an additional mirror mapping might > > introduce additional delay and overhead. In addition, error for > > log devices is better to be handled by the simple way, and a basic > > error handling would work. > > In theory yes, but I doubt it would be user visible that much. We expect > transient failures under some circumstances, so we would like to handle > them. In other words, a failed device is expected to come back and the > mirror target should re-integrate it automatically when it comes back. > Can your multi-log code handle re-synchronizing a log device? > > With our user level only implementation, the log device handling would > be as good as the real mirror *leg* handling. We get all the benefits of > the mirror without doing any code! Wouldn't it be nice? > > > > I couldn't find any discussion after you posted the patch. > > Could you tell me if IBM also have the same background as I have, > > or do you have another issue to solve? I would also like to know > > if my approach solves your problem. > > Jonathan, Alasdair and I had discussions about the patch. I can send > them to you if you want. > > As I said, we want to handle transient device failures. Can your patch > work with such log devices? > > --Malahal. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
