Grow UFS in Solaris

One discussion in toolbox.com give me the idea to write this article. The subject was full root  (/) filesystem and how to extend it. Most of the participants do not believe this is possible, but i will demonstrate how to do it. My demonstration is based on Oracle Solaris 10 Generic_142910-17 i386.

1. What is my OS

# showrev
Hostname: sun02
Hostid: 10b69b13
Release: 5.10
Kernel architecture: i86pc
Application architecture: i386
Hardware provider:
Domain:
Kernel version: SunOS 5.10 Generic_142910-17


2. Check the map of harddisk
#  prtvtoc /dev/dsk/c1t0d0s2
* /dev/dsk/c1t0d0s2 partition map
<snip>
*                          First     Sector    Last
* Partition  Tag  Flags    Sector     Count    Sector  Mount Directory
       0      2    00      16065   2104515   2120579   /
       1      4    00    2570400   6297480   8867879   /usr
       2      5    00          0  33495525  33495524
       3      3    01   11309760   1060290  12370049
       8      1    01          0     16065     16064


As you can see I have some unallocated cylinders after each partition (/. /usr and swap) and this is done on time of installation for the reason of demonstration.

3. Check the exact sizes of filesystems
# df -k / /usr
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/dsk/c1t0d0s0    1019856  377425  581240    40%    /
/dev/dsk/c1t0d0s1    3100362 2251708  786647    75%    /usr
# swap -l
swapfile             dev  swaplo blocks   free
/dev/dsk/c1t0d0s3   30,3       8 1060280 1060280


4. Create two control files, filled with random bytes for control of the integrity of filesystems
# dd if=/dev/urandom of=/checkfileroot bs=1024 count=10240
10240+0 records in
10240+0 records out
# dd if=/dev/urandom of=/usr/checkfileusr bs=1024 count=10240
10240+0 records in
10240+0 records out


5. And get checksums ot the files
# digest -a sha1 /checkfileroot /usr/checkfileusr
(/checkfileroot) = c5ee33c68b147c58e6190a99a647a9baf35581a8
(/usr/checkfileusr) = 77bb739b734ab01a43578479ec4a3abe92e6c4bd


6. Extend slice 0, 1 and 3 with some amount of cylinders
# format
Searching for disks...done

AVAILABLE DISK SELECTIONS:
       0. c1t0d0 <DEFAULT cyl 2085 alt 2 hd 255 sec 63>
          /pci@0,0/pci1000,30@10/sd@0,0
Specify disk (enter its number): 0
selecting c1t0d0
[disk formatted]
Warning: Current Disk has mounted partitions.
/dev/dsk/c1t0d0s0 is currently mounted on /. Please see umount(1M).
/dev/dsk/c1t0d0s1 is currently mounted on /usr. Please see umount(1M).
/dev/dsk/c1t0d0s3 is currently used by swap. Please see swap(1M).

FORMAT MENU:
        disk       - select a disk
        type       - select (define) a disk type
        partition  - select (define) a partition table
        current    - describe the current disk
        format     - format and analyze the disk
        fdisk      - run the fdisk program
        repair     - repair a defective sector
        label      - write label to the disk
        analyze    - surface analysis
        defect     - defect list management
        backup     - search for backup labels
        verify     - read and display labels
        save       - save new disk/partition definitions
        inquiry    - show vendor, product and revision
        volname    - set 8-character volume name
        !<cmd>     - execute <cmd>, then return
        quit
format> p

PARTITION MENU:
        0      - change `0' partition
        1      - change `1' partition
        2      - change `2' partition
        3      - change `3' partition
        4      - change `4' partition
        5      - change `5' partition
        6      - change `6' partition
        7      - change `7' partition
        select - select a predefined table
        modify - modify a predefined partition table
        name   - name the current table
        print  - display the current table
        label  - write partition map and label to the disk
        !<cmd> - execute <cmd>, then return
        quit
partition> 0
Part      Tag    Flag     Cylinders        Size            Blocks
  0       root    wm       1 -  131        1.00GB    (131/0/0)   2104515
Enter partition id tag[root]:
Enter partition permission flags[wm]:
Enter new starting cyl[1]:
Enter partition size[2104515b, 131c, 131e, 1027.60mb, 1.00gb]: 140c
partition> 1
Part      Tag    Flag     Cylinders        Size            Blocks
  1        usr    wm     160 -  551        3.00GB    (392/0/0)   6297480
Enter partition id tag[usr]:
Enter partition permission flags[wm]:
Enter new starting cyl[160]:
Enter partition size[6297480b, 392c, 551e, 3074.94mb, 3.00gb]: 400c
partition> 3
Part      Tag    Flag     Cylinders        Size            Blocks
  3       swap    wu     704 -  769      517.72MB    (66/0/0)    1060290
Enter partition id tag[swap]:
Enter partition permission flags[wu]:
Enter new starting cyl[704]:
Enter partition size[1060290b, 66c, 769e, 517.72mb, 0.51gb]: 80c
partition> la
Ready to label disk, continue? y
partition> q

FORMAT MENU:
        disk       - select a disk
        type       - select (define) a disk type
        partition  - select (define) a partition table
        current    - describe the current disk
        format     - format and analyze the disk
        fdisk      - run the fdisk program
        repair     - repair a defective sector
        label      - write label to the disk
        analyze    - surface analysis
        defect     - defect list management
        backup     - search for backup labels
        verify     - read and display labels
        save       - save new disk/partition definitions
        inquiry    - show vendor, product and revision
        volname    - set 8-character volume name
        !<cmd>     - execute <cmd>, then return
        quit
format> q


7. And the moment of true, extend root (/) filesystem
# growfs -M / /dev/rdsk/c1t0d0s0
Warning: 5748 sector(s) in last cylinder unallocated
/dev/rdsk/c1t0d0s0:     2249100 sectors in 367 cylinders of 48 tracks, 128 sectors
        1098.2MB in 23 cyl groups (16 c/g, 48.00MB/g, 11648 i/g)
super-block backups (for fsck -F ufs -o b=#) at:
 32, 98464, 196896, 295328, 393760, 492192, 590624, 689056, 787488, 885920,
 1279648, 1378080, 1476512, 1574944, 1673376, 1771808, 1870240, 1968672,
 2067104, 2165536

8. Then grow /usr
# growfs -M /usr /dev/rdsk/c1t0d0s1
Warning: 624 sector(s) in last cylinder unallocated
/dev/rdsk/c1t0d0s1:     6426000 sectors in 1046 cylinders of 48 tracks, 128 sectors
        3137.7MB in 66 cyl groups (16 c/g, 48.00MB/g, 5824 i/g)
super-block backups (for fsck -F ufs -o b=#) at:
 32, 98464, 196896, 295328, 393760, 492192, 590624, 689056, 787488, 885920,
 5512224, 5610656, 5709088, 5807520, 5905952, 6004384, 6102816, 6201248,
 6291488, 6389920

9. And swap
# swap -d /dev/dsk/c1t0d0s3
/dev/dsk/c1t0d0s3 was dump device --
invoking dumpadm(1M) -d swap to select new dump device
dumpadm: no swap devices are available
# swap -a /dev/dsk/c1t0d0s3
operating system crash dump was previously disabled --
invoking dumpadm(1M) -d swap to select new dump device
# dumpadm -d swap
      Dump content: kernel pages
       Dump device: /dev/dsk/c1t0d0s3 (swap)
Savecore directory: /var/crash/sun02
  Savecore enabled: yes
   Save compressed: on


For the swap I just delete and add it again. And update dump device, this is important. Of course it is not always possible just to delete virtual memory on production, but its possible to play with creation of new swap device, delete old, add old and delete new. This can take long time on production system, but its relatively safe operation

10. So, let check again the sizes of filesystems
# df -k / /usr
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/dsk/c1t0d0s0    1090677  387745  641741    38%    /
/dev/dsk/c1t0d0s1    3163878 2262020  839851    73%    /usr
# swap -l
swapfile             dev  swaplo blocks   free
/dev/dsk/c1t0d0s3   30,3       8 1285192 1285192


As you can see they are bigger that few minutes a go

11. But what is the situation with control files
# digest -a sha1 /checkfileroot /usr/checkfileusr
(/checkfileroot) = c5ee33c68b147c58e6190a99a647a9baf35581a8
(/usr/checkfileusr) = 77bb739b734ab01a43578479ec4a3abe92e6c4bd


As you can see they are the same

12. Et voila, we successfully extend our filesystems on the fly. By the way in official Oracle Solaris documentations you can see this
--------------
LIMITATIONS
    Only UFS file systems (either mounted or unmounted) can be expanded using the growfs command. Once a file system is expanded, it cannot be decreased in size. The following conditions prevent you from expanding file systems: When acct is activated and the accounting file is on the target device. When C2 security is activated and the logging file is on the target file system. When there is a local swap file in the target file system. When the file system is root (/), /usr, or swap.

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