All of the drives are in a single external enclosure? How is that enclosure connected to the rest of the PC? USB? (2? 3?) eSATA? FireWire? Something else? If eSATA, then you may be having issues with a port multiplier. In any case, it's really hard to troubleshoot by guessing. So, if you'd like further help to address performance issues, maybe you could provide a full hardware and software description of the system. :) Thomas > On Nov 11, 2013, at 9:09 PM, tclug at freakzilla.com wrote: > > No idea what most of what you said is, no (: > > These are all identical drives, in an external enclosure, so none of it is my own SATA cables. And again, no errors when they were in a software RAID5 (though there were half as many drives) and nothing in the system logs, which is why I am concerned... > >> On Mon, 11 Nov 2013, Thomas Lunde wrote: >> >> >> Bit flips like this helped me to discover that two of my 10 SATA cables were marginal. >> >> Since these are >2T drives, did you do anything with ashift? Depending on which ZFS implementation you're using, this question might not make sense? >> >> An array of drives where some are faking 512 byte sectors and ( some are really using 512 byte sectors OR some are using 4K sectors ) can cause abysmal performance. >> >> Thomas >> >> _______________________________________________ >> TCLUG Mailing List - Minneapolis/St. Paul, Minnesota >> tclug-list at mn-linux.org >> http://mailman.mn-linux.org/mailman/listinfo/tclug-list > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list