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Difference between bootdg & rootdg

Rajan_Iyer
Level 4
Certified

Hi

I would like to know more details about difference between bootdg & rootdg terminology.

In my set up below configurations are there

1.vxdg bootdg
rootdg

 

2. While checking all volumes are created under bootdg

 

/dev/vx/dsk/bootdg/rootvol
/dev/vx/dsk/bootdg/abc
/dev/vx/dsk/bootdg/def  
/dev/vx/dsk/bootdg/rnt
 

3. vxdg list

rootdg

My doubt is when expanding any volume do I need to use word "bootdg" or "rootdg" while mentioning the disk group name.

In the same ref. when I am going to add new mount point/file system do I need to use word "bootdg" or "rootdg" while mentioning the disk group name.

 

 

Also let me know the reason.

 

Thanks

 

1 ACCEPTED SOLUTION

Accepted Solutions

Gaurav_S
Moderator
Moderator
   VIP    Certified

Hi Rajan,

From VxVM Admin guide:

System-wide reserved disk groups


The following disk group names are reserved, and cannot be used to name any
disk groups that you create:

bootdg:

Specifes the boot disk group. This is an alias for the disk group that
contains the volumes that are used to boot the system. VxVM sets
bootdg to the appropriate disk group if it takes control of the root
disk. Otherwise, bootdg is set to nodg (no disk group).

 

defaultdg:

Specifies the default disk group. This is an alias for the disk group
name that should be assumed if the -g option is not specified to a
command, or if the VXVM_DEFAULTDG environment variable is
undefined. By default, defaultdg is set to nodg (no disk group).

nodg:


Specifies to an operation that no disk group has been defined. For
example, if the root disk is not under VxVM control, bootdg is set to
nodg

 

So as explained by John as well, bootdg is nothing but an alias to a dg which contains your bootvolumes.

Couple of suggestions / recommendations:

-- It is recommended not to configure any data volumes inside rootdg/bootdg

-- How would u plan to resize the boot volumes ? Be assured on OS & VXVM version you are using. Assuming your bootdg (rootdg) containts all system volumes, here is a note from vxvm admin guide for 5.0 MP3 for solaris

Warning: You cannot grow or shrink any volume associated with an encapsulated
root disk (rootvol, usr, var, opt, swapvol, and so on) because these map to a
physical underlying partition on the disk and must be contiguous. If you attempt
to grow rootvol, usrvol, varvol, or swapvol, the system could become unbootable
if you need to revert back to booting from slices. It can also prevent a successful
Solaris upgrade and you might have to do a fresh install. Additionally, the
upgrade_start script might fail.

Gaurav

 

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4 REPLIES 4

jstucki
Level 4

Here's some useful information  (http://www.symantec.com/business/support/index?page=content&id=TECH31534):

A bootdg alias has been configured to define a disk group that contains the volumes that are used to boot the system.  Volume Manager sets bootdg to the appropriate disk group when the root disk is put under Volume Manager control.  Otherwise, bootdg is set to nodg.

The vxdg bootdg command displays the currently defined system-wide boot disk group whose alias is the reserved name,  bootdg.

So its saying that "bootdg" is an alias to "rootdg", and "rootdg" is your disk group which is used for booting the system.  The real name of the disk group is rootdg.  The bootdg alias was added when VxVM 4.0 was released.

This is a good technote on the subject, but its a bit old:  http://www.symantec.com/business/support/index?page=content&id=TECH54739    It essentially says, "be consistent".  If you use "bootdg" in the /etc/vfstab file, then use "bootdg" when you run commands to change your volumes.

-John

Gaurav_S
Moderator
Moderator
   VIP    Certified

Hi Rajan,

From VxVM Admin guide:

System-wide reserved disk groups


The following disk group names are reserved, and cannot be used to name any
disk groups that you create:

bootdg:

Specifes the boot disk group. This is an alias for the disk group that
contains the volumes that are used to boot the system. VxVM sets
bootdg to the appropriate disk group if it takes control of the root
disk. Otherwise, bootdg is set to nodg (no disk group).

 

defaultdg:

Specifies the default disk group. This is an alias for the disk group
name that should be assumed if the -g option is not specified to a
command, or if the VXVM_DEFAULTDG environment variable is
undefined. By default, defaultdg is set to nodg (no disk group).

nodg:


Specifies to an operation that no disk group has been defined. For
example, if the root disk is not under VxVM control, bootdg is set to
nodg

 

So as explained by John as well, bootdg is nothing but an alias to a dg which contains your bootvolumes.

Couple of suggestions / recommendations:

-- It is recommended not to configure any data volumes inside rootdg/bootdg

-- How would u plan to resize the boot volumes ? Be assured on OS & VXVM version you are using. Assuming your bootdg (rootdg) containts all system volumes, here is a note from vxvm admin guide for 5.0 MP3 for solaris

Warning: You cannot grow or shrink any volume associated with an encapsulated
root disk (rootvol, usr, var, opt, swapvol, and so on) because these map to a
physical underlying partition on the disk and must be contiguous. If you attempt
to grow rootvol, usrvol, varvol, or swapvol, the system could become unbootable
if you need to revert back to booting from slices. It can also prevent a successful
Solaris upgrade and you might have to do a fresh install. Additionally, the
upgrade_start script might fail.

Gaurav

 

View solution in original post

Rajan_Iyer
Level 4
Certified

Hi Gaurav,

 

Thanks for the info.

 

Please let me knoiw can I add any volume under bootdg for data.

 

Will it cause server reboot issue.

 

Thanks

Marianne
Moderator
Moderator
Partner    VIP    Accredited Certified

Best to add data disks to separate diskgroup.

If anything 'happens' to the server, you can attach/zone disks to another server and import the diskgroup.