accessing /dev/zfs is dependent on loading the zfs module which may take
some time for udev to do it's work to create /dev/zfs. However, ZFS
does allow this to be tweaked with the ZFS_MODULE_TIMEOUT environment
variable:
>From lib/libzfs/libzfs_util.c, libzfs_load_module:
/*
* Device creation by udev is asynchronous and waiting may be
* required. Busy wait for 10ms and then fall back to polling every
* 10ms for the allowed timeout (default 10s, max 10m). This is
* done to optimize for the common case where the device is
* immediately available and to avoid penalizing the possible
* case where udev is slow or unable to create the device.
*/
timeout_str = getenv("ZFS_MODULE_TIMEOUT");
...
so export ZFS_MODULE_TIMEOUT=0 may be a useful workaround for the
moment. I wonder if that could be set automagically to zero lxc
environment rather than hacking around zfs to detect if it is in a lxc
container. The former does seem the best way forward.
** Also affects: lxd (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1760173
Title:
zfs, zpool commands hangs for 10 seconds without a /dev/zfs
Status in lxd package in Ubuntu:
New
Status in zfs-linux package in Ubuntu:
Triaged
Bug description:
1. # lsb_release -rd
Description: Ubuntu 16.04.4 LTS
Release: 16.04
2. # apt-cache policy zfsutils-linux
zfsutils-linux:
Installed: 0.6.5.6-0ubuntu19
Candidate: 0.6.5.6-0ubuntu19
Version table:
*** 0.6.5.6-0ubuntu19 500
500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64
Packages
100 /var/lib/dpkg/status
3. When inside a lxd container with zfs storage, zfs list or zpool
status either return or report what's going on.
4. When inside a lxd container with zfs storage, zfs list or zpool
status appears to hang, no output for 10 seconds.
strace reveals that without a /dev/zfs the tools wait for it to appear
for 10 seconds but do not provide a command line switch to disable or
make it more verbose.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: zfsutils-linux 0.6.5.6-0ubuntu19
ProcVersionSignature: Ubuntu 4.13.0-36.40~16.04.1-generic 4.13.13
Uname: Linux 4.13.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
Date: Fri Mar 30 18:09:29 2018
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
LANG=C.UTF-8
SourcePackage: zfs-linux
UpgradeStatus: No upgrade log present (probably fresh install)
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