Unix Admin Reference – Veritas Volume Manager Volume States and Plex States

 

 

While Troubleshooting Veritas Volume Manager, Understanding volume and plex states is key part to investigate about the current issue related to the Veritas Volumes. In this post, I made little effort to write all the possible Volume and Plex states so that it can be readily useful for others ( including me) for the day to day operations. This information is already available in internet in various formats, what I exactly tried here is just a consolidation,  for quick reference.

 

 

 

VXVM Volume States

1.  CLEAN         : The volume is not started (Kernel state DISABLED) and its plexes are synchronized.

2. ACTIVE       : The volume has been started or was in use when the machine was rebooted. If the volume is DISABLED, the plexes cannot be guaranteed to be consistent, but will be consistent when the volume is started.

3. EMPTY        : The volume contents are not initialized. The kernel state is always DISABLED when the volume is EMPTY.

4. SYNC            : The volume is either in read-writeback recovery mode(ENABLED) or was in this mode when the machine was rebooted(DISABLED). With read-writeback recovery, plex consistency is recovered by reading data blocks of one plex and writing the data to all other writable plexes. If the volume is ENABLED, the plexes are being resyncronized.

If volume is DISABLED it was resyncing when machine was rebooted and the plexes need to be resyncronized.

5. NEEDSYNC : The volume will require a resyncronization operation the next time it is started.

 

 

RAID-5 Volume States (Raid-5 have there own set of volume states )

 

1. CLEAN            : The volume is not started and its parity is good. The raid-5 plex stripes are consistent.

2. ACTIVE           : The volume has been started or was in use when the machine was rebooted. If the volume is DISABLED, the parity can’t be guaranteed to be synchronized.

3. EMPTY            : The volume contents are not initialized. The kernel state is always DISABLED when the volume is EMPTY.    

4. SYNC               : The volume is either undergoing a parity resyncronization or was having its parity resyncronization when the machine was rebooted.

5. NEEDSYNC   : The volume will require a parity resyncronization operation the next time it is started.

6. REPLAY          : The volume is in a transient state as part of a log replay. A log replay occurs when it becomes necessary to use logged parity and  data.

 

Plex states

1. EMPTY      :  When a volume is created and the plex isn’t initialized the plex is in an EMPTY state.

2. CLEAN       :   A plex is in a CLEAN state when it is known to contain a good copy (mirror) of  the volume. Therefore all the plexes of a volume are  clean, no action is required.

3. ACTIVE    :  A plex can be in the ACTIVE state in two situations:

When the volume is started and the plex fully participates in normal volume I/O (meaning the plex contents change as the contents of the volume change)

When the volume was stopped as a result of a system crash and the plex was active at the moment of the crash

In the latter case, a system failure may leave plex contents in an inconsistent state. When a volume is started, VxVM performs a recovery action to guarantee that the contents of the plexes are marked as ACTIVE are made identical.

On a well running system – All Plex States Should be “ACTIVE

4. STALE   :  If there is a possibility a plex doesn’t have the complete  and  currently up-to-date volume contents, This plex is placed in a STALE state. Also, if I/O errors occur on a plex, the kernel stops using and updating this plex, and the operation sets the state of the plex to STALE.

To re-attach the plex to the volume you can run the

#  vxplex -g (diskgroup) att volume-name plex-name       

To force a plex into STALE state you can run

# vxplex -g (disk group)  det volume-name plex-name    

 

5. OFFLINE  : We can disable any operations to a plex attached to a volume by making it offline . Although the detached plex is associated with the volume the changes to the volume aren’t reflected to the plex while in the OFFLINE state.

We can offline plex using the below command, which will detach a plex from a volume setting the plex state to OFFLINE

         # vxmend -g diskgroup off volname plexname

And if you want to reattach the plex back to volume so that it will be available for storing volume content you can use below command      

         # vxplex -g (disk group) att volume-name plex-name

Note: When we attach the plex  using the above command it will set the plex state to STALE . And to make the data in Sync and up-to-date with current volume data we use below command.

         #vxvol start vol-name

 

6. TEMP         :  VxVM will set the plex state to TEMP at the start of an operation ..  like adding a new mirror to a volume. The plex will be in this state while it is being associated or attached (sync process). A utility will set the plex state to TEMP at the start of an operation and to an appropriate state at the end of the operation. )

If the system goes down for any reason, a TEMP plex state indicates the operation is incomplete; a subsequent vxvol start     will dissociate plexes in the TEMP state.

 

7. TEMPRM     : A TEMPRM plex state resembles a TEMP state except that at the completion of the operation, the TEMPRM plex is removed.

If the system goes down for any reason, a TEMPRM plex state indicates the operation is incomplete; a subsequent vxvol start will disassociate plexes and remove the TEMPRM plex.

 

8. TEMPRMSD : The TERMPRMSD plex state is used by vxassist when attaching new plexes. If the operation doesn’t complete, the plex and its subdisk are removed.

 

9. IOFAIL        : The IOFAIL plex state is associated with persistent state logging. On the detection of a failure of an ACTIVE plex, vxconfigd places that plex in the IOFAIL state so that it is disqualified from the recovery selection process at volume start time.

 

Plex Kernel States 

The plex kernel state indicates the accessibility of the plex to the volume driver which monitors it. No user intervention is required to set these states; they are maintained internally. On a system that is operating properly, all plexes are enabled

1. DISABLED    :  The plex may not be accessed.

2. DETACHED : A write to the volume is not reflected to the plex. A read request from the volume will never be satisfied from the plex. Plex operations and ioctl functions are accepted.

3. ENABLED    : A write request to the volume will be reflected to the plex. A read request from the volume will be satisfied      from the plex.

you can also check the Veritas Plex state Transition Diagram posted here to know the Plex will change from one to another state

 

 

Ramdev

Ramdev

I have started unixadminschool.com ( aka gurkulindia.com) in 2009 as my own personal reference blog, and later sometime i have realized that my leanings might be helpful for other unixadmins if I manage my knowledge-base in more user friendly format. And the result is today's' unixadminschool.com. You can connect me at - https://www.linkedin.com/in/unixadminschool/

4 Responses

  1. Arora says:

    Hi Ramdev,

    Very helpful consolidated information,Do you have or can you provide the CBT link for Veritas Volume manager….if you have kindly share i am desperately looking for that but i am not getting…

    Regards
    Vikas

  2. chetantare says:

    Hi,

    I want perform SVM to VERITAS conversion activity.
    means currenl FS oracle on /dev/md/dsk/d30 as /oracle that same FS i have convert into veritas as /dev/vx/dsk/oradg/oracle. without lost of single KB file (ENCAPSULATE)

    So i can help me what are the steps that have to take during the activity.

    & 1 more query after conversion can i grow or shrink my FS?????

  1. September 16, 2015

    […] Read – VxMV Quick Reference Guide […]

  2. October 6, 2015

    […] Read – VxVM Volume States and Plex States Read – Veritas Plex state Transition […]

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