Merge pull request #368 from cedric-dufour/master

New Sheet Added: ZFS (on Linux)

cheat/cheatsheets/zfs

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+# WARNING:
+#   In order to avoid headaches when moving ZFS physical devices around,
+#   one will be much better served to reference devices by their *immutable*
+#   ID - as in /dev/disk/by-id/* - rather than their block device name -
+#   as in /dev/{sd,nvme}* - which is bound to change as per PCI enumeration
+#   order.
+# For the sake of briefness, we'll use the following variables:
+#   ${device}    device (/dev/disk/by-id/${device})
+#   ${part}      partition (/dev/disk/by-id/${part=${device}-part${N}})
+#   ${pool}      ZFS pool (name)
+#   ${fs_vol}    ZFS file system or volume (name)
+#   ${snapshot}  ZFS snapshot (name)
+
+
+## Pools
+
+# Create a new "RAID-5" (raidz1) pool
+# Recommended: use entire devices rather than partitions
+zpool create ${pool} raidz1 ${device} ${device} ${device} [...]
+
+# Add 2nd-level "RAID-1" (mirror) ZFS Intent Log (ZIL; synchronous write cache)
+# Recommended: use separate, fast, low-latency devices (e.g. NVMe)
+zpool add ${pool} log mirror ${part} ${part}
+
+# Add 2nd-level "RAID-0" Adaptive Replacement Cache (ARC; read cache)
+# Recommended: use separate, fast, low-latency devices (e.g. NVMe)
+zpool add ${pool} cache ${part} ${part} [...]
+
+# Remove log or cache components
+zpool remove zfs ${part} [...]
+
+# Import (enable) existing pool from newly connected devices
+# Note: this will create the /etc/zfs/zpool.cache devices cache
+zpool import -d /dev/disk/by-id -aN
+
+# Import (enable) existing pool using the devices cache
+zpool import -c /etc/zfs/zpool.cache -aN
+
+# Export (disable) pool (e.g. before shutdown)
+zpool export -a
+
+# List all (imported) pools
+zpool list
+
+# See pool status
+zpool status ${pool}
+
+# See detailed pool I/O statistics
+zpool iostat ${pool} -v
+
+# Verify pool integrity (data checksums)
+# (watch progress with 'zpool status')
+zpool scrub ${pool}
+
+# Remove a failing device from a pool
+# Note: redundant pools (mirror, raidz) will continue working in degraded state
+zpool detach ${pool} ${device}
+
+# Replace a failed device in a pool
+# Note: new device will be "resilvered" automatically (parity reconstruction)
+#       (watch progress with 'zpool status')
+zpool replace ${pool} ${failed-device} ${new-device}
+
+# Erase zpool labels ("superblock") from a device/partition
+# WARNING: MUST do before reusing a device/partition for other purposes
+zpool labelclear ${device}
+
+# Query pool configuration (properties)
+zpool get all ${pool}
+
+# Change pool configuration (property)
+zpool set <property>=<value> ${pool}
+
+# Dump the entire pool (commands) history
+zpool history ${pool}
+
+# More...
+man zpool
+
+
+## File systems / Volumes
+
+# Create a new file system
+zfs create ${pool}/${fs_vol}
+
+# Create a new volume ("block device")
+# Note: look for it in /dev/zvol/${pool}/${fs_vol}
+zfs create -V <size> ${pool}/${fs_vol}
+
+# List all file systems / volumes
+zfs list
+
+# Mount all file systems
+# Note: see 'zfs get mountpoint ${pool}' for mountpoint root path
+zfs mount -a
+
+# Create a snapshot
+zfs snapshot ${pool}/${fs_vol}@${snapshot}
+
+# Delete a snapshot
+zfs destroy ${pool}/${fs_vol}@${snapshot}
+
+# Full backup
+# Note: pipe (|) source to destination through netcat, SSH, etc.
+# ... on source:
+zfs send -p -R ${pool}/${fs_vol}@${snapshot}
+# ... on destination:
+zfs receive -F ${pool}/${fs_vol}
+
+# Incremental backup
+# Note: pipe (|) source to destination through netcat, SSH, etc.
+# ... on source:
+zfs send -p -R -i ${pool}/${fs_vol}@${snapshot-previous} ${pool}/${fs_vol}@${snapshot}
+# ... on destination:
+zfs receive -F ${pool}/${fs_vol}
+
+# Query file system / volume configuration (properties)
+zfs get all ${pool}
+zfs get all ${pool}/${fs_vol}
+
+# Change file system / volume configuration (property)
+zfs set <property>=<value> ${pool}/${fs_vol}
+
+# More...
+man zfs
+