Displaying Plex Information
Listing plexes helps identify free plexes for building volumes. Use the plex (–p) option to the vxprint command to list information about all plexes.
To display detailed information about all plexes in the system, use the following command:
# vxprint -lp
To display detailed information about a specific plex, use the following command:
# vxprint [-g diskgroup] -l plex
The -t option prints a single line of information about the plex. To list free plexes, use the following command:
# vxprint -pt
The following section describes the meaning of the various plex states that may be displayed in the STATE field of vxprint output.
Plex States
Plex states reflect whether or not plexes are complete and are consistent copies (mirrors) of the volume contents. VxVM utilities automatically maintain the plex state. However, if a volume should not be written to because there are changes to that volume and if a plex is associated with that volume, you can modify the state of the plex. For example, if a disk with a particular plex located on it begins to fail, you can temporarily disable that plex.
Note
A plex does not have to be associated with a volume. A plex can be created with the vxmake plex command and be attached to a volume later.
VxVM utilities use plex states to:
- indicate whether volume contents have been initialized to a known state
- determine if a plex contains a valid copy (mirror) of the volume contents
- track whether a plex was in active use at the time of a system failure
- monitor operations on plexes
This section explains the individual plex states in detail. For more information about the possible transitions between plex states and how these are applied during volume recovery, see the chapter "Understanding the Plex State Cycle" in the section "Recovery from Hardware Failure" in the VERITAS Volume Manager Troubleshooting Guide.
Plexes that are associated with a volume have one of the following states:
ACTIVE Plex State
A plex can be in the ACTIVE state in two ways:
- when the volume is started and the plex fully participates in normal volume I/O (the plex contents change as the contents of the volume change)
- when the volume is stopped as a result of a system crash and the plex is ACTIVE at the moment of the crash
In the latter case, a system failure can leave plex contents in an inconsistent state. When a volume is started, VxVM does the recovery action to guarantee that the contents of the plexes marked as ACTIVE are made identical.
Note
On a system running well, ACTIVE should be the most common state you see for any volume plexes.
CLEAN Plex State
A plex is in a CLEAN state when it is known to contain a consistent copy (mirror) of the volume contents and an operation has disabled the volume. As a result, when all plexes of a volume are clean, no action is required to guarantee that the plexes are identical when that volume is started.
DCOSNP Plex State
This state indicates that a data change object (DCO) plex attached to a volume can be used by a snapshot plex to create a DCO volume during a snapshot operation.
EMPTY Plex State
Volume creation sets all plexes associated with the volume to the EMPTY state to indicate that the plex is not yet initialized.
IOFAIL Plex State
The IOFAIL plex state is associated with persistent state logging. When the vxconfigd daemon detects an uncorrectable I/O failure on an ACTIVE plex, it places the plex in the IOFAIL state to exclude it from the recovery selection process at volume start time.
This state indicates that the plex is out-of-date with respect to the volume, and that it requires complete recovery. It is likely that one or more of the disks associated with the plex should be replaced.
LOG Plex State
The state of a dirty region logging (DRL) or RAID-5 log plex is always set to LOG.
OFFLINE Plex State
The vxmend off task indefinitely detaches a plex from a volume by setting the plex state to OFFLINE. Although the detached plex maintains its association with the volume, changes to the volume do not update the OFFLINE plex. The plex is not updated until the plex is put online and reattached with the vxplex att task. When this occurs, the plex is placed in the STALE state, which causes its contents to be recovered at the next vxvol start operation.
SNAPATT Plex State
This state indicates a snapshot plex that is being attached by the snapstart operation. When the attach is complete, the state for the plex is changed to SNAPDONE. If the system fails before the attach completes, the plex and all of its subdisks are removed.
SNAPDIS Plex State
This state indicates a snapshot plex that is fully attached. A plex in this state can be turned into a snapshot volume with the vxplex snapshot command. If the system fails before the attach completes, the plex is dissociated from the volume. See the vxplex(1M) manual page for more information.
SNAPDONE Plex State
The SNAPDONE plex state indicates that a snapshot plex is ready for a snapshot to be taken using vxassist snapshot.
SNAPTMP Plex State
The SNAPTMP plex state is used during a vxassist snapstart operation when a snapshot is being prepared on a volume.
STALE Plex State
If there is a possibility that a plex does not have the complete and current volume contents, that plex is placed in the STALE state. Also, if an I/O error occurs on a plex, the kernel stops using and updating the contents of that plex, and the plex state is set to STALE.
A vxplex att operation recovers the contents of a STALE plex from an ACTIVE plex. Atomic copy operations copy the contents of the volume to the STALE plexes. The system administrator can force a plex to the STALE state with a vxplex det operation.
TEMP Plex State
Setting a plex to the TEMP state eases some plex operations that cannot occur in a truly atomic fashion. For example, attaching a plex to an enabled volume requires copying volume contents to the plex before it can be considered fully attached.
A utility sets the plex state to TEMP at the start of such an operation and to an appropriate state at the end of the operation. If the system fails for any reason, a TEMP plex state indicates that the operation is incomplete. A later vxvol start dissociates plexes in the TEMP state.
TEMPRM Plex State
A TEMPRM plex state is similar to a TEMP state except that at the completion of the operation, the TEMPRM plex is removed. Some subdisk operations require a temporary plex. Associating a subdisk with a plex, for example, requires updating the subdisk with the volume contents before actually associating the subdisk. This update requires associating the subdisk with a temporary plex, marked TEMPRM, until the operation completes and removes the TEMPRM plex.
If the system fails for any reason, the TEMPRM state indicates that the operation did not complete successfully. A later operation dissociates and removes TEMPRM plexes.
TEMPRMSD Plex State
The TEMPRMSD plex state is used by vxassist when attaching new data plexes to a volume. If the synchronization operation does not complete, the plex and its subdisks are removed.
Plex Condition Flags
vxprint may also display one of the following condition flags in the STATE field:
IOFAIL Plex Condition
The plex was detached as a result of an I/O failure detected during normal volume I/O. The plex is out-of-date with respect to the volume, and in need of complete recovery. However, this condition also indicates a likelihood that one of the disks in the system should be replaced.
NODAREC Plex Condition
No physical disk was found for one of the subdisks in the plex. This implies either that the physical disk failed, making it unrecognizable, or that the physical disk is no longer attached through a known access path. The plex cannot be used until this condition is fixed, or the affected subdisk is dissociated.
NODEVICE Plex Condition
A physical device could not be found corresponding to the disk ID in the disk media record for one of the subdisks associated with the plex. The plex cannot be used until this condition is fixed, or the affected subdisk is dissociated.
RECOVER Plex Condition
A disk corresponding to one of the disk media records was replaced, or was reattached too late to prevent the plex from becoming out-of-date with respect to the volume. The plex required complete recovery from another plex in the volume to synchronize its contents.
REMOVED Plex Condition
Set in the disk media record when one of the subdisks associated with the plex is removed. The plex cannot be used until this condition is fixed, or the affected subdisk is dissociated.
Plex Kernel States
The plex kernel state indicates the accessibility of the plex to the volume driver which monitors it.
Note
No user intervention is required to set these states; they are maintained internally. On a system that is operating properly, all plexes are enabled.
The following plex kernel states are defined:
DETACHED Plex Kernel State
Maintenance is being performed on the plex. Any write request to the volume is not reflected in the plex. A read request from the volume is not satisfied from the plex. Plex operations and ioctl function calls are accepted.
DISABLED Plex Kernel State
The plex is offline and cannot be accessed.
ENABLED Plex Kernel State
The plex is online. A write request to the volume is reflected in the plex. A read request from the volume is satisfied from the plex.
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