Hello Andreas Thank you very much for you help. I do have a few more questions.
>> >> Therefore >> My mkfs options should be >> --mkfsoptions="-E stripe=128 -E stride=32" /dev/sdb > > If you are planning on expanding this at the RAID6 level to be an 8+2 > configuration, you should specify "-E stripe=256,stride=64". Are there any potential negatives here? I initially used a 6 disk raid 10 but I ended up with wasted space on the filesystem since I could not fit the 1M lustre I/O into the number of active disks cleanly. Would there be a way to minimize the amount of wasted space if I wanted to stick to raid 1/0? I assume that aligned I/O is always preferred. > Note that you cannot specify mulitple separate "-E" options to mke2fs, it > would only use the last one specified. I want to say I tried the mkfs.lustre "-E stripe=xx,stride=xx" but I received some error. I will see if this happens again. > >> 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. > > Using a 4-disk RAID-10 external journal is unlikely to give you any extra > performance, since journal IO is nearly sequential (though sometimes small > block writes if there are few clients and you are not using async journal). I see. > > Also, 16TB LUN support is only available with ext4, so if you have 2TB drives > you need to make sure to download the right ldiskfs package. > I am creating these filesystems with lustre 1.8.3 from the prebuilt RPMs. Do you mean that there is a different ldiskfs package I should use? I guess this brings up another question. Should i also use the flexible block group options on the OSTs? -O flex_bg and -G nr_merged_groups > Depending on the hardware options on your RAID, it may be that you need a > separate hot spare for each LUN, in which case having 2 hot spares makes > sense. Otherwise, you can probably use only 13 or 14 drives. > >> Is my understanding of the documentation accurate? >> Do both of these options seem like potential upgrade options? > > Either of them seem reasonable. > > If the hardware allows in-place RAID reshaping then it is possible. I'd > always recommend to make a backup before doing this, because one never knows > what might happen if this operation is interrupted for some reason. Understood. Thanks Again Sebastian _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
