Chapter 14 RAID 5 Volumes (Tasks)
This chapter provides information about performing Solaris Volume Manager
tasks that are associated with RAID 5 volumes. For information about the concepts
involved in these tasks, see Chapter 13, RAID 5 Volumes (Overview).
RAID 5 Volumes (Task Map)
The following task map identifies the procedures needed to manage Solaris Volume Manager
RAID 5 volumes.
Creating RAID 5 Volumes
Caution –
Do not create volumes larger than 1TB if you expect to run
the Solaris Operating Environment with a 32–bit kernel or if you expect
to use a version of the Solaris Operating Environment prior to Solaris 9 4/03.
See Overview of Large Volume Support in Solaris Volume Manager for more information about large
volume support in Solaris Volume Manager.
How to Create a RAID 5 Volume
-
Check Prerequisites for Creating Solaris Volume Manager Components and Background Information for Creating RAID 5 Volumes.
-
To create the RAID 5 volume, use one of the following methods:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node, then choose Action->Create
Volume and follow the steps in the wizard. For more information, see the online
help.
-
Use the following form of the metainit
command:
metainit name -r component component component
|
-
name is the name for the volume
to create.
-
r specifies to create a RAID 5
volume.
-
component specifies a slice or
soft partition to include in the RAID 5 volume.
To specify an interlace value, add the -i interlace-value option. For more information, see the metainit(1M) man page.
Example—Creating a RAID 5 Volume of Three Slices
# metainit d45 -r c2t3d0s2 c3t0d0s2 c4t0d0s2
d45: RAID is setup
|
In this example, the RAID 5 volume d45 is created
with the -r option from three slices. Because no interlace
value is specified, d45 uses the default of 16 Kbytes.
The system verifies that the RAID 5 volume has been set up, and begins initializing
the volume.
You must wait for the initialization to finish before you can use the
RAID 5 volume.
Where to Go From Here
To prepare the newly created RAID 5 volume for a file system, see “Creating
File Systems (Tasks)” in System Administration Guide: Basic
Administration. An application, such as a database, that
uses the raw volume must have its own way of recognizing the volume.
To associate a hot spare pool with a RAID 5 volume, see How to Associate a Hot Spare Pool With a Volume.
Maintaining RAID 5 Volumes
How to Check the Status of a RAID 5 Volume
To check status on a RAID 5 volume, use one of the following methods:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node and view the status
of the volumes. Choose a volume, then choose Action->Properties to see more
detailed information. For more information, see the online help.
-
Use the metastat command.
For each slice in the RAID 5 volume, the metastat
command shows the following:
-
“Device” (device name of the slice in the stripe)
-
“Start Block” on which the slice begins
-
“Dbase” to show if the slice contains a state
database replica
-
“State” of the slice
-
“Hot Spare” to show the slice being used to hot
spare a failed slice
Example—Viewing RAID 5 Volume Status
Here is sample RAID 5 volume output from the metastat
command.
# metastat
d10: RAID
State: Okay
Interlace: 32 blocks
Size: 10080 blocks
Original device:
Size: 10496 blocks
Device Start Block Dbase State Hot Spare
c0t0d0s1 330 No Okay
c1t2d0s1 330 No Okay
c2t3d0s1 330 No Okay
|
The metastat command output identifies the volume
as a RAID 5 volume. For each slice in the RAID 5 volume, it shows the name
of the slice in the stripe, the block on which the slice begins, an indicator
that none of these slices contain a state database replica, that all the slices
are okay, and that none of the slices are hot spare replacements for a failed
slice.
RAID 5 Volume Status Information
The following table explains RAID 5 volume states.
Table 14–1 RAID 5 States
|
State
|
Meaning
|
|
Initializing
|
Slices are in the process of having all disk
blocks zeroed. This process is necessary due to the nature of RAID 5 volumes
with respect to data and parity interlace striping.
Once the
state changes to “Okay,” the initialization process is complete
and you are able to open the device. Up to this point, applications receive
error messages.
|
|
Okay
|
The device is ready for use and is currently free from
errors.
|
|
Maintenance
|
A slice has been marked as failed due to I/O
or open errors that were encountered during a read or write operation.
|
The slice state is perhaps the most important information when you are
troubleshooting RAID 5 volume errors. The RAID 5 state only provides general
status information, such as “Okay” or “Needs Maintenance.”
If the RAID 5 reports a “Needs Maintenance” state, refer to the
slice state. You take a different recovery action if the slice is in the “Maintenance”
or “Last Erred” state. If you only have a slice in the “Maintenance”
state, it can be repaired without loss of data. If you have a slice in the “Maintenance”
state and a slice in the “Last Erred” state, data has probably
been corrupted. You must fix the slice in the “Maintenance” state
first then the “Last Erred” slice. See Overview of Replacing and Enabling Components in RAID 1 and RAID 5
Volumes.
The following table explains the slice states for a RAID 5 volume and
possible actions to take.
Table 14–2 RAID 5 Slice States
|
State
|
Meaning
|
Action
|
|
Initializing
|
Slices are in the process of having all disk
blocks zeroed. This process is necessary due to the nature of RAID 5 volumes
with respect to data and parity interlace striping.
|
Normally none. If an I/O error occurs during
this process, the device goes into the “Maintenance” state. If
the initialization fails, the volume is in the “Initialization Failed”
state, and the slice is in the “Maintenance” state. If this happens,
clear the volume and re-create it.
|
|
Okay
|
The device is ready for use and is currently free from
errors.
|
None. Slices
can be added or replaced, if necessary.
|
|
Resyncing
|
The slice is actively being resynchronized.
An error has occurred and been corrected, a slice has been enabled, or a slice
has been added.
|
If desired,
monitor the RAID 5 volume status until the resynchronization is done.
|
|
Maintenance
|
A single slice has been marked as failed due
to I/O or open errors that were encountered during a read or write operation.
|
Enable or replace the
failed slice. See How to Enable a Component in a RAID 5 Volume, or How to Replace a Component in a RAID 5 Volume.
The metastat command will show an invoke
recovery message with the appropriate action to take with the metareplace command.
|
|
Maintenance/ Last Erred
|
Multiple slices have encountered errors.
The state of the failed slices is either “Maintenance” or “Last
Erred.” In this state, no I/O is attempted on the slice that is in the “Maintenance”
state, but I/O is attempted to the slice marked “Last Erred” with
the outcome being the overall status of the I/O request.
|
Enable or replace the failed slices. See How to Enable a Component in a RAID 5 Volume, or How to Replace a Component in a RAID 5 Volume.
The metastat command will show an invoke
recovery message with the appropriate action to take with the metareplace command, which must be run with the -f flag. This
state indicates that data might be fabricated due to multiple failed slices.
|
Note –
RAID 5 volume initialization or resynchronization cannot be interrupted.
How to Expand a RAID 5 Volume
In general, attaching components is a short-term solution to a RAID
5 volume that is running out of space. For performance reasons, it is best
to have a “pure” RAID 5 volume. If you must expand an existing
RAID 5 volume to gain extra storage space, use this procedure.
Caution –
Do not create volumes larger than 1TB if you expect to run
the Solaris Operating Environment with a 32–bit kernel or if you expect
to use a version of the Solaris Operating Environment prior to Solaris 9 4/03.
See Overview of Large Volume Support in Solaris Volume Manager for more information about large
volume support in Solaris Volume Manager.
-
Make sure that you have a current backup of all data and that you have
root access.
-
Read Background Information for Creating RAID 5 Volumes.
-
To attach additional components to a RAID 5 volume, use one of the following
methods:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node, then open the RAID
5 volume. Choose the Components pane, then choose Attach Component and follow
the instructions. For more information, see the online help.
-
Use the following form of the metattach
command:
metattach volume-name name-of-component-to-add
|
See the metattach(1M)
man page for more information.
Example—Adding a Component to a RAID 5 Volume
# metattach d2 c2t1d0s2
d2: column is attached
|
This example shows the addition of slice c2t1d0s2
to an existing RAID 5 volume named d2.
Where to Go From Here
For a UFS, run the growfs command on the RAID 5 volume.
See Volume and Disk Space Expansion.
An application, such as a database, that uses the raw volume must have
its own way of growing the added space.
How to Enable a Component in a RAID 5 Volume
Note –
If a disk drive is defective, you can replace it with another
available disk (and its slices) on the system as documented in How to Replace a Component in a RAID 5 Volume.
Alternatively, you can repair/replace the disk, label it, and run the metareplace command with the -e option.
-
Make sure that you have a current backup of all data and that you have
root access.
-
To enable a failed component in a RAID 5 volume, use one of the following
methods:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node, then open the RAID
5 volume. Choose the Components pane, then choose the failed component. Click
Enable Component and follow the instructions. For more information, see the
online help.
-
Use the following form of the metareplace
command:
metareplace -e volume-name component-name
|
-
-e specifies to replace the failed component
with a component at the same location (perhaps after physically replacing
a disk).
-
volume-name is the name of the
volume with a failed component.
-
component-name specifies the name
of the component to replace.
metareplace automatically starts resynchronizing
the new component with the rest of the RAID 5 volume.
Example—Enabling a Component in a RAID 5 Volume
# metareplace -e d20 c2t0d0s2
|
In this example, the RAID 5 volume d20 has a slice, c2t0d0s2, which had a soft error. The metareplace
command with the -e option enables the slice.
How to Replace a Component in a RAID 5 Volume
This task replaces a failed slice
of a RAID 5 volume in which only one slice has failed.
Caution –
Replacing a failed slice when multiple slices are in error
might cause data to be fabricated. The integrity of the data in this instance
would be questionable.
You can use the metareplace command on non-failed
devices to change a disk slice or other component. This procedure can be useful
for tuning the performance of RAID 5 volumes.
-
Make sure that you have a current backup of all data and that you have
root access.
-
Use one of the following methods to determine which slice of the RAID
5 volume needs to be replaced:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node, then open the RAID
5 volume. Choose the Components pane, then view the status of the individual
components. For more information, see the online help.
-
Use the metastat command.
Look for the keyword “Maintenance” to identify the failed
slice.
-
Use one of the following methods to replace the failed slice with another
slice:
-
From the Enhanced Storage tool within the Solaris Management Console, open the Volumes node, then open the RAID
5 volume. Choose the Components pane, then choose the failed component. Click
Replace Component and follow the instructions. For more information, see the
online help.
-
Use the following form of the metareplace
command:
metareplace volume-name failed-component new-component
|
-
volume-name is the name of the
volume with a failed component.
-
failed-component specifies the
name of the component to replace.
-
new-component specifies the name
of the component to add to the volume in place of the failed component.
See the metareplace(1M)
man page for more information.
-
To verify the status of the replacement slice, use one of the methods
described in Step 2.
The state of the replaced slice should be “Resyncing” or “Okay”.
Example—Replacing a RAID 5 Component
# metastat d1
d1: RAID
State: Needs Maintenance
Invoke: metareplace d1 c0t14d0s6 <new device>
Interlace: 32 blocks
Size: 8087040 blocks
Original device:
Size: 8087520 blocks
Device Start Block Dbase State Hot Spare
c0t9d0s6 330 No Okay
c0t13d0s6 330 No Okay
c0t10d0s6 330 No Okay
c0t11d0s6 330 No Okay
c0t12d0s6 330 No Okay
c0t14d0s6 330 No Maintenance
# metareplace d1 c0t14d0s6 c0t4d0s6
d1: device c0t14d0s6 is replaced with c0t4d0s6
# metastat d1
d1: RAID
State: Resyncing
Resync in progress: 98% done
Interlace: 32 blocks
Size: 8087040 blocks
Original device:
Size: 8087520 blocks
Device Start Block Dbase State Hot Spare
c0t9d0s6 330 No Okay
c0t13d0s6 330 No Okay
c0t10d0s6 330 No Okay
c0t11d0s6 330 No Okay
c0t12d0s6 330 No Okay
c0t4d0s6 330 No Resyncing
|
In this example, the metastat command
displays the action to take to recover from the failed slice in the d1 RAID 5 volume. After locating an available slice, the metareplace command is run, specifying the failed slice first, then
the replacement slice. (If no other slices are available, run the metareplace command with the -e option to attempt
to recover from possible soft errors by resynchronizing the failed device.)
If multiple errors exist, the slice in the “Maintenance” state
must first be replaced or enabled. Then the slice in the “Last Erred”
state can be repaired. After the metareplace command, the metastat command monitors the progress of the resynchronization.
During the replacement, the state of the volume and the new slice will is “Resyncing.”
You can continue to use the volume while it is in this state.
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