Hi, I was wondering if you could shed some light on possible data corruption issues when accessing an AoE-exported device directly on the AoE target?
I'm running clustered LVM (clvm) on top of AoE, the partition containing the PV is exported using ggaoed. ggaoed opens the device (eg /dev/sda3) in exclusive mode to avoid data corruption. Is this really necessary when using DLM to ensure exclusive access? The problem is accessing the exported device directly on the AoE target, i.e. on the host running ggaoed. Since ggaoed is running in direct-io mode anything received over the network will hit the disk right away but local access could still use the buffer cache. One solution would be to export the AoE-volume over localhost as well but that is a quite significant performance hit since all I/O then has to pass through user-space then. To summarize, the question is: Would the following setup be safe? Node_A: - LVM PV on /dev/sda3 - VG named "test_vg" - exporting /dev/sda3 using ggaoed using direct-io Node_B: - AoE access to PV of "test_vg" from Host_A Node_C: - AoE access to PV of "test_vg" from Host_A Then running corosync,dlm,clvmd,etc on all nodes, would a GFS deployment be safe even though Host_A accesses /dev/sda3 directly? regards, Ralf PS. The request-merging feature in ggaoed nicely solved the performance problem I had with direct-i/o. DS. ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Aoetools-discuss mailing list Aoetools-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aoetools-discuss
