WIKI Liberasys

From https://pve.proxmox.com/wiki/ZFS_on_Linux

Also called “striping”. The capacity of such volume is the sum of the capacities of all disks. But RAID0 does not add any redundancy, so the failure of a single drive makes the volume unusable.

Also called “mirroring”. Data is written identically to all disks. This mode requires at least 2 disks with the same size. The resulting capacity is that of a single disk.

A combination of RAID0 and RAID1. Requires at least 4 disks.

A variation on RAID-5, single parity. Requires at least 3 disks.

A variation on RAID-5, double parity. Requires at least 4 disks.

A variation on RAID-5, triple parity. Requires at least 5 disks.

• automatically partitions the disks,
• creates a ZFS pool called rpool,
• installs the root file system on the ZFS subvolume rpool/ROOT/pve-1
• creates another subvolume called rpool/data to store VM images

RQ : It is not possible to use ZFS as root file system with UEFI boot. RQ : Always use GPT partition tables. RQ : ashift = 12 sets 4k blocks IOs with the disks RQ : DO NOT use SWAP over ZFS !

man zpool
man zfs
vi /etc/sysctl.conf # vm.swappiness = 10
apt-get install zfs-zed # mail notification
vi /etc/zfs/zed.d/zed.rc # change ZED_EMAIL_ADDR="root" if needed

• GPT partition table on the SSD device :
  • log : memory size / 1.8 (the maximum size of a log device should be about half the size of physical memory)
  • cache : the rest
• add (add log/cache SSD disk) : zpool add -f <pool> log <device-part1> cache <device-part2>
• replace (replace failing SSD disk) : zpool replace -f <pool> <old device> <new-device>

vi /etc/modprobe.d/zfs.conf # change "options zfs zfs_arc_max=" to memory size / 2 at most, and 8 Go + FS size in TB * 1 GB at min ; ex : 8589934592 for 8GB RAM usage

if ZFS is root FS, do : update-initramfs -u

A dataset is a filesystme over a ZFS pool. A ZVOL is a virtual logic volume. Proxmox stores VM disks over a ZVOL and contener's disk over a dataset.