Difference between revisions of "Zpool"
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== Creating a pool == | == Creating a pool == | ||
| − | In the past, it was customary to label the | + | In the past, it was customary to label (i.e., partition) the disks before using them with ZFS. This is no longer the case. Now the preferred method is to have ZFS label the disks for you. |
| − | + | ||
| − | + | The case-sensitivity default is sensitive, but some 3rd party apps on OS X don't work entirely right if you have a case-sensitive volume. Normalization default is none, though OS X likes [http://en.wikipedia.org/wiki/Unicode_equivalence#Normal_forms NFD normalization], or you may have some issues with characters. | |
| − | + | ||
| + | The default for ashift is 9, but you will most likely want to create pools with an ashift of 12, which is appropriate for 4096 (4k) disks (i.e., Advanced Format disks), even if your disks are still the older 512. If you are using SSDs in your pool now, or anticipate replacing any of your pool's disks with SSDs in the future, then an ashift of 13 is a better choice. It is important to get this right now because a vdev's ashift cannot be changed after the vdev is created. | ||
'''Recommended pool creation command line''' | '''Recommended pool creation command line''' | ||
| − | zpool create -f -O casesensitivity=insensitive -O normalization=formD | + | zpool create -f -o ashift=12 \ |
| + | -O casesensitivity=insensitive \ | ||
| + | -O normalization=formD \ | ||
| + | $poolname mirror /dev/diskX /dev/diskY | ||
* Replace $poolname with the name of the pool you want, for example "tank". | * Replace $poolname with the name of the pool you want, for example "tank". | ||
* ''If you want to use the entire disk for ZFS'', replace /dev/diskX with the available disk. For example /dev/disk1 | * ''If you want to use the entire disk for ZFS'', replace /dev/diskX with the available disk. For example /dev/disk1 | ||
* If you have already partitioned the disk, and wish to only use a slice, use /dev/disk1s2 | * If you have already partitioned the disk, and wish to only use a slice, use /dev/disk1s2 | ||
| + | * -f instructs ZFS to label the disk for you. | ||
Use "diskutil list" to make sure you pick the correct disk before attempting to create your pool. | Use "diskutil list" to make sure you pick the correct disk before attempting to create your pool. | ||
| − | You can also decide to disable '''access time''', enable '''compression''' and all those nice things. But that | + | You can also decide to disable '''access time''', enable '''compression,''' and all those nice things. But that can be done at any time in ZFS. For example |
| − | can be done at any time in ZFS. For example | + | |
| + | zfs set compression=lz4 $poolname | ||
| + | |||
| + | or for pool version 28 compatibility | ||
zfs set compression=on $poolname | zfs set compression=on $poolname | ||
| + | Because turning compression on later will only apply to new data added to a dataset, not the preexisting uncompressed data, if you do want compression, you should turn it on as soon as possible, or enable it at the time the pool is created. | ||
| + | |||
| + | For example, you may want to use something like this | ||
| + | zpool create -f -o ashift=12 \ | ||
| + | -O compression=lz4 \ | ||
| + | -O casesensitivity=insensitive \ | ||
| + | -O atime=off \ | ||
| + | -O normalization=formD \ | ||
| + | tank mirror /dev/disk3 /dev/disk4 | ||
| + | If you absolutely must be compatible with non-OpenZFS implementations of ZFS (e.g., Oracle Solaris), you'd need to do | ||
| + | zpool create -f -o version=28 -o ashift=12 \ | ||
| + | -O compression=on \ | ||
| + | -O casesensitivity=insensitive \ | ||
| + | -O atime=off \ | ||
| + | -O normalization=formD \ | ||
| + | tank mirror /dev/disk3 /dev/disk4 | ||
== Unplugging a pool == | == Unplugging a pool == | ||
Revision as of 21:00, 12 March 2014
Creating a pool
In the past, it was customary to label (i.e., partition) the disks before using them with ZFS. This is no longer the case. Now the preferred method is to have ZFS label the disks for you.
The case-sensitivity default is sensitive, but some 3rd party apps on OS X don't work entirely right if you have a case-sensitive volume. Normalization default is none, though OS X likes NFD normalization, or you may have some issues with characters.
The default for ashift is 9, but you will most likely want to create pools with an ashift of 12, which is appropriate for 4096 (4k) disks (i.e., Advanced Format disks), even if your disks are still the older 512. If you are using SSDs in your pool now, or anticipate replacing any of your pool's disks with SSDs in the future, then an ashift of 13 is a better choice. It is important to get this right now because a vdev's ashift cannot be changed after the vdev is created.
Recommended pool creation command line
zpool create -f -o ashift=12 \ -O casesensitivity=insensitive \ -O normalization=formD \ $poolname mirror /dev/diskX /dev/diskY
- Replace $poolname with the name of the pool you want, for example "tank".
- If you want to use the entire disk for ZFS, replace /dev/diskX with the available disk. For example /dev/disk1
- If you have already partitioned the disk, and wish to only use a slice, use /dev/disk1s2
- -f instructs ZFS to label the disk for you.
Use "diskutil list" to make sure you pick the correct disk before attempting to create your pool.
You can also decide to disable access time, enable compression, and all those nice things. But that can be done at any time in ZFS. For example
zfs set compression=lz4 $poolname
or for pool version 28 compatibility
zfs set compression=on $poolname
Because turning compression on later will only apply to new data added to a dataset, not the preexisting uncompressed data, if you do want compression, you should turn it on as soon as possible, or enable it at the time the pool is created.
For example, you may want to use something like this
zpool create -f -o ashift=12 \ -O compression=lz4 \ -O casesensitivity=insensitive \ -O atime=off \ -O normalization=formD \ tank mirror /dev/disk3 /dev/disk4
If you absolutely must be compatible with non-OpenZFS implementations of ZFS (e.g., Oracle Solaris), you'd need to do
zpool create -f -o version=28 -o ashift=12 \ -O compression=on \ -O casesensitivity=insensitive \ -O atime=off \ -O normalization=formD \ tank mirror /dev/disk3 /dev/disk4
Unplugging a pool
Pool export is not yet automatic in Open ZFS on OS X. Before you unplug any devices should must export all pools used by the device.
zpool export $poolname
The export can sometimes fail if the mount is busy (as with all filesystems). So you might need to close any windows still accessing the ZFS volume. If you are just rebooting, you need not export first.
