Hello This will probably be a pretty basic question however I wanted to verify that I was understanding the documentation correctly.
The enclosure I am using supports 15 disks. We have initially ordered 6 disks + hostpare. I think my recommendation is going to be a 6 disk raid 6. Which will give us a 4 data disk raid set plus 2 parity disks. Later we will have the option to create another 6 disk raid6 or expand the current raid set to a 10 disk raid 6 then move the journal to a 4 disk raid 1/0 and have 1 disk hot spare. The current Raid 6 will have a 128k chunksize (lustre terminology) this gives us: <stripe_width> = <chunksize> * (<disks> - <parity_disks>) <=1MB 512K <= 128k*4 <chunksize> <= 1024kB/4; either 256k, 128k, 64k 256k = < = 1024k/4k <chunk_blocks> = <chunksize(decided above)> / 4k 32 = 256/4 128k = 512k / 4k <stripe_width_blocks> = <stripe_width> / 4k Therefore My mkfs options should be --mkfsoptions="-E stripe=128 -E stride=32" /dev/sdb upgrade options: The filesystem chunk_block options would still be valid since the chunk_blocks would stay the same. purchase 6 more disks This will allow for a new raid 6 that is aligned the same way with 3 hotspares. or (I need clarification if this understanding is correct) purchase 10 more disks Expand the current raid 6 to a larger 10 disk/raid 6 with a 4 disk raid 1/0 for a external journal plus a hot spare. Is my understanding of the documentation accurate? Do both of these options seem like potential upgrade options? Cheers, Sebastian _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
