Hello Colin, I have a couple more screen shots showing the raw performance of both drives; the first using 512MiB as you suggested and the second with a larger sample and using the dd commands status=progress option to monitor for pauses. Also in the second ss, I performed the test on an iso file from the zfs file system. I did not see any pauses on the raw devices, but then I only saw momentary pauses (one second or less) on the zfs file. Regards, Colin.
** Attachment added: "raw device performance" https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1725859/+attachment/5114647/+files/dd-1.png -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to zfs-linux in Ubuntu. https://bugs.launchpad.net/bugs/1725859 Title: zfs frequently hangs (up to 30 secs) during sequential read Status in zfs-linux package in Ubuntu: Incomplete Bug description: Updated to artful (17.10) yesterday. Trying to read (play video) from mirrored ZFS disks from an external USB 3 enclosure. Zpool is defined as: root@hetty:/home/crlb# zpool status pool: storage state: ONLINE scan: resilvered 20K in 0h0m with 0 errors on Fri Oct 20 18:38:49 2017 config: NAME STATE READ WRITE CKSUM storage ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 sdb ONLINE 0 0 0 sdc ONLINE 0 0 0 errors: No known data errors root@hetty:/home/crlb# Found that I could re-create the problem with: rsync -av --progress <zfs_file> <internal_ext4_path> Also found that: dd if=/dev/sdX of=/dev/null status=progress bs=1024 count=10000000 Where "X" is either "b" or "c" does not hang. Installed: root@hetty:/home/crlb# apt list --installed | grep -i zfs libzfs2linux/artful,now 0.6.5.11-1ubuntu3 amd64 [installed,automatic] zfs-zed/artful,now 0.6.5.11-1ubuntu3 amd64 [installed,automatic] zfsutils-linux/artful,now 0.6.5.11-1ubuntu3 amd64 [installed] root@hetty:/home/crlb# Help please. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1725859/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
