Jeff Morrow <jmorrow@jmorrow.org> wrote: > I've created a software RAID 5 array consisting of 8 160 GB drives. One > of the drives had prior data I wanted to keep, so I first created a > 7-drive array, copied the data from the original drive to the array, > then added the 8th drive using raidreconf. Worked like a charm (took > about 27 hours, though!) > > The OS now reports that the total capacity on /dev/md0 is about 920 GB: > > /dev/md0 923029884 172872252 750157632 19% /mnt/store > > Now, even if we take into account that the drives are 160 decimal GB, > which equates to 149 binary GB, my array should still have a total > capacity somewhere around 7 x 149 = 1043 GB. > > Am I really losing 120 GB to reserved space for RAID and/or filesystem > accounting? I feel like I'm missing something obvious here. Can I get > my full terabyte somehow? So you created a RAID5 array out of 7 disk. The capacity of a RAID5 array of equally sized disk can be calculated like this: total_size = (n -1) * single_disk_size which calculates to a total size of 894MB - 960MB (depending on how you calculate a MegaByte). The extra disk that you added is most certainly now seen as a spare disk which adds now capacity to the array, just a instant replacement in case of failures. What you should have done: Create a degraded RAID5 array out of 8 drives with the 8th one marked as missing/failed. Then copy all the data from the 8th drive to the array. After this hot-add the 8th drive to degraded array and let it rebuild. Regards, Juri -- Juri Haberland <juri@koschikode.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
