I've been using MD raid + LVM for many years, but recently decided to take a look at ZFS. In order to try it, I created a VirtualBox VM with a similar layout to my main server - 7 'SATA' drives or various sizes.I set it up with an approximation of my current MD+LVM configuration and proceeded to work out the steps I needed to follow to rearrange files, LVs, VGs etc, to make space to try ZFS. All seemed ok - I moved and rearranged PVs until I had the space set up over a period of 3 days uptime.Finally, I created the first ZPool:  pool: tank state: ONLINE  scan: none requestedconfig:    NAME        STATE     READ WRITE CKSUM    tank        ONLINE       0     0     0      raidz1-0  ONLINE       0     0     0        sdb1    ONLINE       0     0     0        sdc1    ONLINE       0     0     0        sdd1    ONLINE       0     0     0        sde1    ONLINE       0     0     0        sdg1    ONLINE       0     0     0errors: No known data errorsI created a couple of ZFS datasets and started copying files using both cp and tar. E.g. cd /data/video;tar cf - .|(cd /tank/video;tar xvf -).I then noticed that I was getting SATA errors in the virtual machine, although the host system shows no errors.Apr  6 10:24:56 model-zfs kernel: [291246.888769] ata4.00: exception Emask 0x0 SAct 0x400 SErr 0x0 action 0x6 frozenApr  6 10:24:56 model-zfs kernel: [291246.888801] ata4.00: failed command: WRITE FPDMA QUEUEDApr  6 10:24:56 model-zfs kernel: [291246.888830] ata4.00: cmd 61/19:50:2b:a7:01/00:00:00:00:00/40 tag 10 ncq 12800 outApr  6 10:24:56 model-zfs kernel: [291246.888830]          res 40/00:01:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)Apr  6 10:24:56 model-zfs kernel: [291246.888852] ata4.00: status: { DRDY }Apr  6 10:24:56 model-zfs kernel: [291246.888883] ata4: hard resetting linkApr  6 10:24:57 model-zfs kernel: [291247.248428] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300)Apr  6 10:24:57 model-zfs kernel: [291247.249216] ata4.00: configured for UDMA/133Apr  6 10:24:57 model-zfs kernel: [291247.249229] ata4.00: device reported invalid CHS sector 0Apr  6 10:24:57 model-zfs kernel: [291247.249254] ata4: EH completeThis error occurs multiple times on various different drives, occasionally with a failed command of 'READ FPDMA QUEUED' or (twice) 'WRITE DMA', to the extent that the kernel eventually reports:Apr  6 11:51:32 model-zfs kernel: [296442.857945] ata4.00: NCQ disabled due to excessive errorsThis does not stop the errors being reported.An internet search showed that this error had been logged on the VirtualBox.org web sites about 4 years ago (https://www.virtualbox.org/ticket/8311) for version 4.0.2 of VirtualBox and was apparently considered fixed, but then reopened.I'm running VirtualBox 4.3.18_Debian r96516 on Debian (Sid) kernel version 3.16.0-4-amd64 (which is also the guest OS as well as host OS). ZFS is version 0.6.3 for ZFSonLinux.org/debian.html.I would have thought more work had been done on this in the intervening years as I can't believe I'm the only person to try out ZFS under VirtualBox so would have thought this error would have been identified and resolved especially as versions of both ZFS and VirtualBox are maintained by Oracle.Or is it simply the case that ZFS stresses the virtual machine to its limits and the simulated drive/controller just can't respond fast enough?Update:In the 14 hours since I created a pool, the VM has reported 204 kernel ata erors. Most of the failed commands are 'WRITE FPDMA QUEUED', followed by 'READ FPDMA QUEUED', 'WRITE DMA' and a single 'FLUSH CACHE'. Presumably, ZFS retried the commands, but so far I am wary of using ZFS on a real server if it's producing so many errors on a virtual machine!
Does ZFS for Linux over stress VirtualBox?
linux;virtualbox;zfs;sata