On 2016-03-09 21:25, Nicholas D Steeves wrote: > grr. Gmail is terrible :-/ > > I understood that a btrfs RAID1 would at best grab one block from sdb > and then one block from sdd in round-robin fashion, or at worse grab > one chunk from sdb and then one chunk from sdd. Alternatively I > thought that it might read from both simultaneously, to make sure that > all data matches, while at the same time providing single-disk > performance. None of these was the case. Running a single > IO-intensive process reads from a single drive. > > Did I misunderstand the documentation and is this normal, or is this a bug? > Nicholas
In a case of a BTRFS RAID, I knew that a process read from a drive depending by its pid. I don't know if it is changed. But what from you write it seems that it still true today. > > On 9 March 2016 at 15:21, Nicholas D Steeves <nstee...@gmail.com> wrote: >> Hello everyone, >> >> I've run into an expected behaviour for a my two disk RAID1. I mount >> with UUIDs, because sometimes my USB disk gets /dev/sdc instead of >> /dev/sdd. The two elements of my RAID1 are currently sdb and sdd. >> >> dstat -tdD total,sdb,sdc,sdd >> >> It seems that per process, reads come from either sdb or sdd. This >> surprises me, because I understood that a btrfs RAID1 > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
