In this example, FreeBSD has already been installed on a single disk, ada0. A new disk, ada1, has been connected to the system. A one-disk mirror will be created on the new disk, the existing system copied onto it, and then the old disk will be inserted into the mirror. This slightly complex procedure is required because gmirror(8) needs to put a 512-byte block of metadata at the end of each disk, and the existing ada0 has usually had all of its space already allocated.
Load the gmirror(8) kernel module:
# gmirror load
Check the media size of the original disk with diskinfo(8):
# diskinfo -v ada0 | head -n3 /dev/ada0 512 # sectorsize 1000204821504 # mediasize in bytes (931G)
Create a mirror on the new disk. To make certain that the mirror capacity is not any larger than the original drive, gnop(8) is used to create a fake drive of the exact same size. This drive does not store any data, but is used only to limit the size of the mirror. When gmirror(8) creates the mirror, it will restrict the capacity to the size of gzero.nop, even if the new drive (ada1) has more space. Note that the 1000204821504 in the second line should be equal to ada0's media size as shown by diskinfo(8) above.
# geom zero load # gnop create -s 1000204821504 gzero # gmirror label -v gm0 gzero.nop ada1 # gmirror forget gm0
gzero.nop does not store any data, so the mirror does not see it as connected. The mirror is told to “forget” unconnected components, removing references to gzero.nop. The result is a mirror device containing only a single disk, ada1.
After creating gm0, view the partition table on ada0.
This output is from a 1 TB drive. If there is some unallocated space at the end of the drive, the contents may be copied directly from ada0 to the new mirror.
However, if the output shows that all of the space on the disk is allocated like the following listing, there is no space available for the 512-byte gmirror(8) metadata at the end of the disk.
# gpart show ada0 => 63 1953525105 ada0 MBR (931G) 63 1953525105 1 freebsd [active]
In this case, the partition table must be edited to reduce the capacity by one sector on mirror/gm0. The procedure will be explained later.
In either case, partition tables on the primary disk should be copied first with the gpart(8) backup and restore subcommands.
# gpart backup ada0 > table.ada0 # gpart backup ada0s1 > table.ada0s1
These commands create two files, table.ada0 and table.ada0s1. This example is from a 1 TB drive:
# cat table.ada0 MBR 4 1 freebsd 63 1953525105 [active] # cat table.ada0s1 BSD 8 1 freebsd-ufs 0 4194304 2 freebsd-swap 4194304 33554432 4 freebsd-ufs 37748736 50331648 5 freebsd-ufs 88080384 41943040 6 freebsd-ufs 130023424 838860800 7 freebsd-ufs 968884224 984640881
If the output of gpart show shows no free space at the end of the disk, the size of both the slice and the last partition must be reduced by one sector. Edit the two files, reducing the size of both the slice and last partition by one. These are the last numbers in each listing.
# cat table.ada0 MBR 4 1 freebsd 63 1953525104 [active] # cat table.ada0s1 BSD 8 1 freebsd-ufs 0 4194304 2 freebsd-swap 4194304 33554432 4 freebsd-ufs 37748736 50331648 5 freebsd-ufs 88080384 41943040 6 freebsd-ufs 130023424 838860800 7 freebsd-ufs 968884224 984640880
If at least one sector was unallocated at the end of the disk, these two files can be used without modification.
Now restore the partition table into mirror/gm0:
# gpart restore mirror/gm0 < table.ada0 # gpart restore mirror/gm0s1 < table.ada0s1
Check the partition table with gpart show. This example has gm0s1a for /, gm0s1d for /var, gm0s1e for /usr, gm0s1f for /data1, and gm0s1g for /data2.
# gpart show mirror/gm0 => 63 1953525104 mirror/gm0 MBR (931G) 63 1953525042 1 freebsd [active] (931G) 1953525105 62 - free - (31k) # gpart show mirror/gm0s1 => 0 1953525042 mirror/gm0s1 BSD (931G) 0 2097152 1 freebsd-ufs (1.0G) 2097152 16777216 2 freebsd-swap (8.0G) 18874368 41943040 4 freebsd-ufs (20G) 60817408 20971520 5 freebsd-ufs (10G) 81788928 629145600 6 freebsd-ufs (300G) 710934528 1242590514 7 freebsd-ufs (592G) 1953525042 63 - free - (31k)
Both the slice and the last partition should have some free space at the end of each disk.
Create filesystems on these new partitions. The number of partitions will vary, matching the partitions on the original disk, ada0.
# newfs -U /dev/mirror/gm0s1a # newfs -U /dev/mirror/gm0s1d # newfs -U /dev/mirror/gm0s1e # newfs -U /dev/mirror/gm0s1f # newfs -U /dev/mirror/gm0s1g
Make the mirror bootable by installing bootcode in the MBR and bsdlabel and setting the active slice:
# gpart bootcode -b /boot/mbr mirror/gm0 # gpart set -a active -i 1 mirror/gm0 # gpart bootcode -b /boot/boot mirror/gm0s1
Йесли у наз избользуедза ГыПыТы, то делайем
# gpart bootcode -b /boot/pmbr -p /boot/gptboot -i 1 ada0
Adjust /etc/fstab to use the new partitions on the mirror. Back up this file first by copying it to /etc/fstab.orig.
# cp /etc/fstab /etc/fstab.orig
Edit /etc/fstab, replacing /dev/ada0 with mirror/gm0.
# Device Mountpoint FStype Options Dump Pass# /dev/mirror/gm0s1a / ufs rw 1 1 /dev/mirror/gm0s1b none swap sw 0 0 /dev/mirror/gm0s1d /var ufs rw 2 2 /dev/mirror/gm0s1e /usr ufs rw 2 2 /dev/mirror/gm0s1f /data1 ufs rw 2 2 /dev/mirror/gm0s1g /data2 ufs rw 2 2
If the gmirror(8) kernel module has not been built into the kernel, edit /boot/loader.conf to load it:
geom_mirror_load="YES"
Filesystems from the original disk can now be copied onto the mirror with dump(8) and restore(8). Note that it may take some time to create a snapshot for each filesystem dumped with dump -L.
# mount /dev/mirror/gm0s1a /mnt # dump -C16 -b64 -0aL -f - / | (cd /mnt && restore -rf -) # mount /dev/mirror/gm0s1d /mnt/var # mount /dev/mirror/gm0s1e /mnt/usr # mount /dev/mirror/gm0s1f /mnt/data1 # mount /dev/mirror/gm0s1g /mnt/data2 # dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr && restore -rf -) # dump -C16 -b64 -0aL -f - /var | (cd /mnt/var && restore -rf -) # dump -C16 -b64 -0aL -f - /data1 | (cd /mnt/data1 && restore -rf -) # dump -C16 -b64 -0aL -f - /data2 | (cd /mnt/data2 && restore -rf -)
Restart the system, booting from ada1. If everything is working, the system will boot from mirror/gm0, which now contains the same data as ada0 had previously. See the Troubleshooting section if there are problems booting.
At this point, the mirror still consists of only the single ada1 disk.
After booting from mirror/gm0 successfully, the final step is inserting ada0 into the mirror.
Important: When ada0 is inserted into the mirror, its former contents will be overwritten by data on the mirror. Make certain that mirror/gm0 has the same contents as ada0 before adding ada0 to the mirror. If there is something wrong with the contents copied by dump(8) and restore(8), revert /etc/fstab to mount the filesystems on ada0, reboot, and try the whole procedure again.
# gmirror insert gm0 ada0 GEOM_MIRROR: Device gm0: rebuilding provider ada0 Synchronization between the two disks will start immediately. gmirror(8) status shows the progress. # gmirror status Name Status Components mirror/gm0 DEGRADED ada1 (ACTIVE) ada0 (SYNCHRONIZING, )
After a while, synchronization will finish.
GEOM_MIRROR: Device gm0: rebuilding provider ada0 finished.
# gmirror status Name Status Components mirror/gm0 COMPLETE ada1 (ACTIVE) ada0 (ACTIVE)
mirror/gm0 now consists of the two disks ada0 and ada1, and the contents are automatically synchronized with each other. In use, mirror/gm0 will behave just like the original single drive.
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