I am arriving here as I would also like to run containers (docker) over
a zpool as the storage backend. In my case, I am running Ubuntu Server
(Focal) on a Pi 3B, I would ideally have root on zfs but with it being a
Pi, I have not done this yet. I have an externally attached USB pool for
real data and have left the OS as it is on the SD card, however, as the
above says, I would like to move more of my systems towards ZFS with
time and use Ubuntu-based distros and containers on a lot of them, where
these can't be run under illumos as VMs.
I have installed docker-rootless on this system, however due to kernel
limitations, it is impossible to mount datasets as non-root on linux
(long-standing issue, I am working on a bug report with details of
options for a workaround and will attach), and using a noverlay over the
top of zfs would be fine for me, as I can snapshot and work with the
higher-level system and back up easily, even if not as fast as native
zfs performance, however, the daemon will not start, and I have fallen
back to the "vfs" driver on my data-root filesystem.
Some googling hasn't indicated what feature(s) would be required in zfs for
overlay to be used on top, docker's documentation doesn't seem to clarify
anything, and searching for the "fstype=1" requirement in xfs, I find from the
manual page for `mkfs.xfs`:
```
ftype=value
This feature allows the inode type to be stored in
the directory structure so that the readdir(3) and
getdents(2) do not need to look up the inode to
determine the inode type.
```
which perhaps is not the issue at hand.
--
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/1718761
Title:
It's not possible to use OverlayFS (mount -t overlay) to stack
directories on a ZFS volume
Status in zfs-linux package in Ubuntu:
Confirmed
Bug description:
---------- Configuration
# echo -e $(grep VERSION= /etc/os-release)\\nSIGNATURE=\"$(cat
/proc/version_signature)\"
VERSION="16.04.3 LTS (Xenial Xerus)"
SIGNATURE="Ubuntu 4.10.0-35.39~16.04.1-generic 4.10.17"
# dpkg --list | grep zfs
ii libzfs2linux 0.6.5.6-0ubuntu18
ii zfs-doc 0.6.5.6-0ubuntu18
ii zfs-initramfs 0.6.5.6-0ubuntu18
ii zfs-zed 0.6.5.6-0ubuntu18
ii zfsutils-linux 0.6.5.6-0ubuntu18
---------- Fault: Creating an overlay of multiple directories on a ZFS volume
does not work
# df /var/tmp
Filesystem Type 1K-blocks Used Available Use% Mounted on
tank07/var/tmp zfs 129916288 128 129916160 1% /var/tmp
# mkdir /var/tmp/{lower,middle,upper,workdir,overlay}
# mount -t overlay overlay
-olowerdir=/var/tmp/middle:/var/tmp/lower,upperdir=/var/tmp/upper,workdir=/var/tmp/workdir
/var/tmp/overlay
mount: wrong fs type, bad option, bad superblock on overlay,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so.
# dmesg|tail -1
[276328.438284] overlayfs: filesystem on '/var/tmp/upper' not supported as
upperdir
---------- Control test 1: Creating an overlay of multiple directories on
another filesystem works
# df /tmp
Filesystem Type 1K-blocks Used Available Use% Mounted on
tmpfs tmpfs 1048576 133492 915084 13% /tmp
# mkdir /tmp/{lower,middle,upper,workdir,overlay}
# mount -t overlay overlay
-olowerdir=/tmp/middle:/tmp/lower,upperdir=/tmp/upper,workdir=/tmp/workdir
/tmp/overlay
# mount | grep overlay
overlay on /tmp/overlay type overlay
(rw,relatime,lowerdir=/tmp/middle:/tmp/lower,upperdir=/tmp/upper,workdir=/tmp/workdir)
---------- Control test 2: Creating an overlay using AuFS works on ZFS volume
and elsewhere
# mount -t aufs -obr=/tmp/lower:/tmp/middle:/tmp/upper:/tmp/workdir none
/tmp/overlay
# mount -t aufs
-obr=/var/tmp/lower:/var/tmp/middle:/var/tmp/upper:/var/tmp/workdir none
/var/tmp/overlay
# mount | grep aufs
none on /var/tmp/overlay type aufs (rw,relatime,si=9ead1ecae778b250)
none on /tmp/overlay type aufs (rw,relatime,si=9ead1ec9257d1250)
---------- Remark
While the use of AuFS can be used as a workaround in the above scenario, AuFS
in turn will not work with [fuse.]glusterfs mounts (this has been documented
elsewhere). Given that OverlayFS is part of the (upstream) kernel and Ubuntu
now officially supports ZFS, the above should be fixed.
---
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Sep 18 16:12 seq
crw-rw---- 1 root audio 116, 33 Sep 18 16:12 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq',
'/dev/snd/timer'] failed with exit code 1:
DistroRelease: Ubuntu 16.04
IwConfig: Error: [Errno 2] No such file or directory
Lspci: Error: [Errno 2] No such file or directory
Lsusb: Error: [Errno 2] No such file or directory
MachineType: Red Hat KVM
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
Package: linux (not installed)
PciMultimedia:
ProcFB: 0 cirrusdrmfb
ProcKernelCmdLine:
BOOT_IMAGE=/ROOT/ubuntu1604@/boot/vmlinuz-4.10.0-35-generic
root=ZFS=tank07/ROOT/ubuntu1604 ro
ProcVersionSignature: Ubuntu 4.10.0-35.39~16.04.1-generic 4.10.17
RelatedPackageVersions:
linux-restricted-modules-4.10.0-35-generic N/A
linux-backports-modules-4.10.0-35-generic N/A
linux-firmware 1.157.12
RfKill: Error: [Errno 2] No such file or directory
Tags: xenial
Uname: Linux 4.10.0-35-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:
_MarkForUpload: True
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.9.1-5.el7_3.3
dmi.chassis.type: 1
dmi.chassis.vendor: Red Hat
dmi.chassis.version: RHEL 7.3.0 PC (i440FX + PIIX, 1996)
dmi.modalias:
dmi:bvnSeaBIOS:bvr1.9.1-5.el7_3.3:bd04/01/2014:svnRedHat:pnKVM:pvrRHEL7.3.0PC(i440FX+PIIX,1996):cvnRedHat:ct1:cvrRHEL7.3.0PC(i440FX+PIIX,1996):
dmi.product.name: KVM
dmi.product.version: RHEL 7.3.0 PC (i440FX + PIIX, 1996)
dmi.sys.vendor: Red Hat
---
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Sep 18 16:12 seq
crw-rw---- 1 root audio 116, 33 Sep 18 16:12 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq',
'/dev/snd/timer'] failed with exit code 1:
DistroRelease: Ubuntu 16.04
IwConfig: Error: [Errno 2] No such file or directory
Lspci: Error: [Errno 2] No such file or directory
Lsusb: Error: [Errno 2] No such file or directory
MachineType: Red Hat KVM
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
Package: linux (not installed)
PciMultimedia:
ProcFB: 0 cirrusdrmfb
ProcKernelCmdLine:
BOOT_IMAGE=/ROOT/ubuntu1604@/boot/vmlinuz-4.10.0-35-generic
root=ZFS=tank07/ROOT/ubuntu1604 ro
ProcVersionSignature: Ubuntu 4.10.0-35.39~16.04.1-generic 4.10.17
RelatedPackageVersions:
linux-restricted-modules-4.10.0-35-generic N/A
linux-backports-modules-4.10.0-35-generic N/A
linux-firmware 1.157.12
RfKill: Error: [Errno 2] No such file or directory
Tags: xenial
Uname: Linux 4.10.0-35-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:
_MarkForUpload: True
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.9.1-5.el7_3.3
dmi.chassis.type: 1
dmi.chassis.vendor: Red Hat
dmi.chassis.version: RHEL 7.3.0 PC (i440FX + PIIX, 1996)
dmi.modalias:
dmi:bvnSeaBIOS:bvr1.9.1-5.el7_3.3:bd04/01/2014:svnRedHat:pnKVM:pvrRHEL7.3.0PC(i440FX+PIIX,1996):cvnRedHat:ct1:cvrRHEL7.3.0PC(i440FX+PIIX,1996):
dmi.product.name: KVM
dmi.product.version: RHEL 7.3.0 PC (i440FX + PIIX, 1996)
dmi.sys.vendor: Red Hat
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