On Tue, 12 Nov 2013, Linda Kateley wrote: > There is a variable called zfs_max_vdev_pending. It sets the queue size for > all disks. I only know the solaris well, Yeah... sadly I can't find anything about getting to that under Linux at all! Ironically I found some references to it on MacOS! I'm actually just this close to nuking this thing and going back to md-sfotware RAID with xfs or btrfs. I just can't have 6 second delays when trying to watch a movie... but I know there is something > similar in linux. It is set to 10 by default. You may want to up this to 2-5 > per disk queue. With the 10, and 8 disks, it is pretty low. Maybe try 24. If > this number is set too high you may see spiky cpu. The cpu will be managing > the queue. > > linda > > On 11/11/13 11:37 PM, tclug at freakzilla.com wrote: >> Hehe. One external, 8-bay enclosure, using two SATA ports. The ports go >> directly to the motherboard - no additional controller. Server software is >> Ubuntu 12.10, with ZFS added on from the zfs-native PPA. >> >> When I was using this as md-software RAID5, I had two disks in each half of >> the enclosure. No performance issues. Now this is 8 disks rather than 4, >> and raidz2 (so RAID6) rather than RAID5, but still... hit play on a video >> and wait 6 seconds for it to start?... that's a bit... off. No errors >> except the three checksum errors I've had. >> >> >> On Mon, 11 Nov 2013, Thomas Lunde wrote: >> >>> >>> 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 >>> _______________________________________________ >>> 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 > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list >