ZFS does not automatically mount legacy file systems at boot time, and the ZFS mount and umount commands do not operate on datasets of this type. The following examples show how to set up and manage a ZFS dataset in legacy mode:. The device to fsck and fsck pass entries are set to - because the fsck command is not applicable to ZFS file systems. ZFS automatically mounts file systems when file systems are created or when the system boots. Use of the zfs mount command is necessary only when you need to change mount options, or explicitly mount or unmount file systems.
The zfs mount command with no arguments shows all currently mounted file systems that are managed by ZFS. Legacy managed mount points are not displayed. For example:. You can use the -a option to mount all ZFS managed file systems. Legacy managed file systems are not mounted. By default, ZFS does not allow mounting on top of a nonempty directory. To force a mount on top of a nonempty directory, you must use the -O option. Legacy mount points must be managed through legacy tools.
An attempt to use ZFS tools results in an error. When a file system is mounted, it uses a set of mount options based on the property values associated with the dataset. The correlation between properties and mount options is as follows:. If any of the mount options described in the preceding section are set explicitly by using the -o option with the zfs mount command, the associated property value is temporarily overridden.
These property values are reported as temporary by the zfs get command and revert back to their original values when the file system is unmounted. I actually tried this just a few weeks ago, albeit using a zvol, and ZFS vehemently refused to import the pool. Other file systems like on Linux ext4 and probably others handle this situation somewhat gracefully, but ZFS balks. If you are unlucky, and don't have ECC RAM installed in the system where you are importing the pool, then ZFS' attempting to correct any errors it encounters might actually make things worse , although opinions differ on whether this is actually a real risk in practice.
So, you can import the pool in read-only mode, with a specific alternate root to keep it from stepping on anything else's toes, but you need to be aware that it isn't necessarily truly read-only in a forensic sense. It will, however, ensure that you don't accidentally change anything in the pool. These property values are "temporary" in the sense that they are not persisted to the disk s as current property values, so if you export and re-import the pool without them, the values will be back to normal.
Just to add, there is another property for datasets canmount which can either be on off noauto off and noauto prevent auto-mounting as well for individual datasets. For more info use man zfs. Hope this help someone. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Stack Gives Back Safety in numbers: crowdsourcing data on nefarious IP addresses.
Featured on Meta. Dynamic strip — Its a very basic pool which can be created with a single disk or a concatenation of disk. We have already seen zpool creation using a single disk in the example of creating zpool with disks. Lets see how we can create concatenated zfs pool. This configuration does not provide any redundancy. Hence any disk failure will result in a data loss. Also note that once a disk is added in this fashion to a zfs pool may not be removed from the pool again.
Only way to free the disk is to destroy entire pool. This happens due to the dynamic striping nature of the pool which uses both disk to store the data. Mirrored pool a. Here you can also detach a disk from the pool as the data will be available on the another disks.
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