How to Migrate a File System to a ZFS File System

If you are migrating data from a remote NFS server, confirm that the name service information is accessible on both remote and local systems.

For a large migration using NFS, you might consider doing a test migration of a subset of the data to ensure that the UID, GUID, and ACL information migrates correctly.
If necessary, install the shadow-migration package on the target system.
```
$ pkg install shadow-migration
```
Enable the shadowd service.
```
$ svcadm enable shadowd
```
Set the local or remote file system to be migrated to read-only.
- If you are migrating a local ZFS file system, set it to read-only. For example:
```
$ zfs set readonly=on tank/home/data
```
- If you are migrating a remote file system, share it as read-only. For example:
```
$ share -F nfs -o ro /export/home/ufsdata
```
Create the target file system while setting the shadow file to the file system to be migrated.
Note:
The new target ZFS file system must be completely empty. Otherwise, migration will not start.

Specify the shadow setting depending on the type of system you are migrating.
- If you are migrating a local file system, specify the source path.
  
  For example:
```
$ zfs create -o shadow=file:///west/home/data users/home/shadow
```
- If you are migrating a NFS file system. specify the source host name and path.
  
  For example:
```
$ zfs create -o shadow=nfs://neo/export/home/ufsdata users/home/shadow2
```
To check the progress of the migration, issue the shadowstat command.

For examples of how to monitor migrations, see Example 7-11.

Note:
Migrating file system data over NFS can be slow, depending on your network bandwidth. If the system is rebooted during migration, the migration continues after the system boot completes.

Example 7-11 Starting and Monitoring File System Migrations

In this example, multiple migrations are initiated. The shadowadm command lists ongoing migrations while the shadowstat command monitors their progress.

$ zfs create -o shadow=nfs://system2/rpool/data/jsmith/archive rpool/data/copyarchive
$ shadowadm list
PATH                                        STATE
/rpool/data/copyarchive                     ACTIVE

$ zfs create -o shadow=nfs://system2/rpool/data/jsmith/datalogs rpool/data/logcopy
$ shadowadm list
PATH                                        STATE
/rpool/data/copyarchive                     ACTIVE
/rpool/data/logcopy                         ACTIVE

$ shadowstat
                                        EST
                                BYTES   BYTES           ELAPSED
DATASET                         XFRD    LEFT    ERRORS  TIME
rpool/data/copyarchive          34.4M   3.37G   -       00:00:36
rpool/data/logcopy              1.12K   155K    1       (completed)Errors are detected.
rpool/data/copyarchive          34.5M   3.37G   -       00:00:37
rpool/data/logcopy              1.12K   155K    1       (completed)
rpool/data/copyarchive          35.0M   3.37G   -       00:00:38
rpool/data/logcopy              1.12K   155K    1       (completed)
rpool/data/copyarchive          35.2M   3.37G   -       00:00:39
rpool/data/logcopy              1.12K   155K    1       (completed)
^C

The previous shadowstat output indicates errors in the migration to rpool/data/logcopy.

The following output from the shadowstat -E and shadowstate -e commands show that migration to rpool/data/logcopy could not be completed because socket migration is not supported. The shadowadm command cancels the migration.

$ shadowstat -E
rpool/data/copyarchive:
No errors encountered.
rpool/data/logcopy:
PATH                                                   ERROR
errdir/cups-socket                                     Operation not supported

$ shadowstat -e /rpool/data/logcopy
rpool/data/logcopy:
PATH                                                   ERROR
errdir/cups-socket                                     Operation not supported

$ shadowadm cancel /rpool/data/logcopy

The following output shows information about the migration to rpool/data/copyarchive, which continues toward completion.

$ shadowadm list
PATH                                        STATE
/rpool/data/copyarchive                     ACTIVE$ shadowstat
                                        EST             
                                BYTES   BYTES           ELAPSED
DATASET                         XFRD    LEFT    ERRORS  TIME
rpool/data/copyarchive          251M    3.16G   -       00:01:27
rpool/data/copyarchive          251M    3.16G   -       00:01:28
rpool/data/copyarchive          252M    3.16G   -       00:01:29
^C

$ shadowstat
No migrations in progress.
$ shadowadm list
$ exit