Hello Colin, Thank you for responding. To Answer your questions: 1. I have two external drives, sdb and sdc, in USB 3 Orico enclosure. The drives are mirrored. 2. Atom D525 with 4GiB RAM. The attached screenshot shows "vmstat 5 5" output while VLC is playing a movie. It shows 1.5GiB of free memory, no swap used. 3. Screenshot also shows output from "iostat -mx", and that I manually set the spl_kmem_cache_slab_limit to zero as suggested.
I played a movie which paused repeatedly for 30 seconds and one time for several minutes. When the pause occurs, VLC is completely hung until the requested I/O completes. The end of pause is heralded by the I/O activity LED on the drive enclosure. I want to emphasize/re-iterate a couple of points from my original post: 1. This is not a VLC problem. I can recreate the problem with any app (cp, rsyn, etc) that reads sequentially from the ZFS file system. 2. I do not believe this is a drive/latency problem: I can dd the content of sdb and sdc (to /dev/null) without any hang. Regards, Colin. ** Attachment added: "spl_kmem_cache_slab_limit, vmstat, and iostat -mx" https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1725859/+attachment/5113194/+files/spl.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
