Kai, This sounds like a job for either OpenGFS or DRBD. http://opengfs.sourceforge.net/ http://www.complang.tuwien.ac.at/reisner/drbd/ Sean. > On Sunday May 25, k@kaisung.com wrote: > > Hi Neil, > > I should probably elaborate a little more on my envisioned > > setup. I'd like to setup a RAID array using shared disks, then run LVM > > on top of the RAID array to carve out logical volumes. The logical > > volumes would be used by one node at a time (no data sharing). For both > > nodes to access the same LVM metadata, they must both activate the RAID > > array. It seemed like someone had done something similar here: > > > > http://marc.theaimsgroup.com/?l=linux-raid&m=98834623209225&w=2 > > > > Concerning the checksums, I was referring to the checksum output when I > > run mdadm --examine on a RAID disk. I thought that was a checksum of all > > the data blocks of the disk, but I guess not? So, basically the only > > time you can guarantee a RAID array is consistent is once it's been > > deactivated and the dirty flag cleared in the superblock? > > It isn't clear what the auther of the refered mail is really doing, > but I stand by my position that this cannot work. > > A raid array is not just a bunch of discs. It is also a controller. > With Linux Soft raid, that controller is a computer running Linux. > In the case of hardware raid, it might be an embeded system on a board > somewhere. But there is still a single controller. > > It probably would not be impossible to arrange a soft RAID system > where separate controller (Linux systems) could co-operate and manage > separate parts of the array, but it would be a lot of work. > > > The checksum is the checksum of the superblock, not the whole array. > Yes. Yoo can only guarantee consustency if the dirty flag is clear. > > NeilBrown > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Sean C. Kormilo, STORM Software Architect, Nortel Networks email: skormilo@nortelnetworks.com - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
