In an IRIX window, use raidcli getagent to get the device name (node number):

raidcli getagent 

If necessary, use raidcli getdisk to verify the disk positions.

Use raidcli unbind to unbind the individual disk units:

raidcli -d device unbind lun-number [-o] 

In this syntax, device is the device name as returned by getagent and lun-number is the number of the logical unit to unbind. The -o flag specifies that the user is not prompted for permission.

The unbind parameter has no output.

Determine the amount of memory you can use for each SP. If necessary, use raidcli getcache to determine each SP's total memory. Look for Raid 3 memory size for spA/spB in the output.

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Note: For RAID-3, you must allocate at least 2 MB of RAID-3 memory per LUN for each SP. Failover requires a minimum of 4 MB per LUN for each SP. See the guidelines in “Planning a RAID-3 Bind,” earlier in this chapter.

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Quiesce the bus: log users off and back up the system. The system cannot be used during RAID-3 memory allocation.

Make sure read and write caches are disabled and there are no unassigned dirty pages. For example:

raidcli -d sc4d2l0 getcache

In the output, look for these lines:

Cache State: Disabled
...
Unassigned Cache Pages: 0 
... 
Prct Dirty Cache Pages = 0 
... 
SPA Read Cache State enabled 
SPB Read Cache State enabled

Use raidcli setcache to set the total amount of caching dedicated to RAID-3. (For full details of setcache, see “Setting Cache Parameters” in Chapter 7.)

Note these guidelines:

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Caution: Setting RAID-3 cache memory reboots the firmware. Make sure the system is not in use before proceeding.

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The following example sets the RAID-3 cache to 6 MB:

raidcli -d sc4d2l0 setcache 1 -r3 6

For failover, RAID-3 memory assigned to each SP must be the total of the SPs used in the failover system. This example sets the RAID-3 cache for a system in which each SP has 6 MB:

raidcli -d sc4d2l0 setcache 1 -r3 12

When you press <Enter> to complete the command, a message informs you that the SPs will be rebooted.

Wait two minutes; then stop and restart the RAID agent:

/etc/init.d/raid5 stop 
/etc/init.d/raid5 start 

Create LUNs for each SP using the -r3 option to allocate RAID-3 memory; for example:

raidcli -d sc4d2l0 bind r3 2 a2 b2 c2 d2 e2 -r3 4
raidcli -d sc2d2l0 bind r3 3 a3 b3 c3 d3 e3 -r3 4 

In this example:

For failover, you must set a total of the memory for this SP's LUNs plus that of the other SP; each SP must have the same amount of memory allocated. That is, the RAID-3 cache memory you set with raidcli bind -r3 for each SP must be half the amount you have set with raidcli setcache -r3 in step 4. See “Planning a RAID-3 Bind,” earlier in this chapter.

Open the Summary View window for the Challenge RAID storage system. Figure 4-4 shows an example.

Figure 4-4. Summary View

Click the button of a LUN you want to unbind. The LUN information window appears, as shown in Figure 4-5.

Figure 4-5. LUN Information Window

Click Unbind. Verification dialog boxes appear; answer them appropriately to unbind the individual disk unit.

The SP unbinds the LUN. In the Bind window, the black outline disappears from around the disk module buttons, and select buttons appear next to the disk module buttons for the newly unbound disk modules. In the Summary View window, the state of the newly unbound disk modules changes from Enabled to Unbound, the LUN number disappears from next to the disk module buttons, and the button for the LUN that was unbound disappears.

Log users off the system and back it up. The system cannot be used during allocation of RAID-3 memory.

Disable automatic polling. Choose “Poll Settings...” in the Options menu and set Manual Polling n the Poll Settings window.

Make sure read and write caches are disabled and no unassigned dirty pages exist:

As in the example, the Cache Status for both read and write caches should be Disabled, the percentage of dirty pages should be 0%, and the number of unassigned dirty pages should be 0.

Close the SP Cache Summary window and the SP Summary window.

Click Cache in the Equipment or Summary View.

In the SP Cache Settings window that appears, click Parameters.... The SP Cache Parameters window appears, as shown in Figure 4-7.

Figure 4-7. Allocating Memory for RAID-3

In the RAID3 text field for each SP used for RAID-3, set SP memory, noting these guidelines:

(Other settings in this window are explained in “Setting Cache Parameters” in Chapter 7.)

When you allocate RAID-3 memory for one SP, the software automatically allocates the same amount of RAID-3 memory for the other SP.

When you are satisfied with the memory allocation, click Set in the Cache Parameters window. A message appears:

Current settings will cause FLARE to reboot, Continue?

Click Yes in this window. The firmware reboot starts. A message appears, as shown in Figure 4-8.

Figure 4-8. Setting the RAID-3 Memory Change

Click OK and exit RAID5GUI.

After two minutes have elapsed since the firmware reboot began, stop and restart the RAID agent and restart RAID5GUI:

/etc/init.d/raid5 stop 
/etc/init.d/raid5 start 
/usr/raid5/raid5gui 

To speed up the binding operation, turn off automatic polling; see “Using RAID5GUI Automatic Polling” in Chapter 3. To see status information during binding, poll for it manually by clicking Poll in the Equipment or Summary View toolbar.

Click Bind in the Equipment View or Summary View. The Bind window for that chassis appears; Figure 4-9 shows an example for RAID-5 LUNs.

Figure 4-9. Bind Window: RAID-5 LUN

You can also open this window by selecting “Bind” in the Equipment View or Summary View's Configure menu.

The disk module buttons in the Bind window resemble those in the Summary View window. You can click on a disk module button to display information about it.

A disk module button for an unbound disk has a select button next to it, as shown in Figure 4-9.

The parameters for the LUN that you can select in the Bind window vary, depending on the RAID level. Table 4-2 summarizes the LUN parameters that are available for the various RAID levels.

In the Raid Type text field, select the RAID level for the first LUN you want to create. If you plan to use different RAID levels for the LUNs you create, follow the order specified in “Planning the Bind,” earlier in this chapter.

If you select RAID-3, the Bind window changes; Figure 4-10 shows an example.

Figure 4-10. Bind Window: RAID-3 LUN

Notice that selecting RAID-3 disables the LUN caching and element size selections and displays a section for RAID-3 memory allocation.

In the LUN (Hex) text field, select the LUN number you want for the first LUN.

The default number is 0 for the first LUN that you bind, regardless of the number of SPs or hosts attached to the Challenge RAID storage system. The default number for the second LUN you bind is 1; for the third LUN, it is 2; for the fourth LUN, it is 3, and so on. You can select nondefault numbers if desired.

The Challenge RAID storage system allows a maximum of eight LUNs (0-7).

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Note: For hot spares, assign LUN numbers starting with the highest number available and continue downward.

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All disk modules in a bind should have the same capacity to use the modules' disk space fully.

If the LUN you are creating is RAID-1, -1_0, -3, or -5, use the Rebuild Time text field to select a different rebuild time from the default 4 hours, if desired.

The rebuild time is the amount of time that the storage system allots to reconstruct the data on either a hot spare or a new disk module that replaces a failed disk module in a LUN. It applies to all RAID LUNs except RAID-0. The time you specify determines the amount of resource the SP devotes to rebuilding instead of to normal I/O activity.

The default time of 4 hours is adequate for most situations. A rebuild time of 2 hours rebuilds the disk more quickly, but degrades response time slightly. A rebuild time of 0 hours rebuilds the disk module as quickly as possible, but degrades response time significantly. If your site requires fast response time and you want to minimize degradation to normal I/O activity, you can extend the rebuilding process over a longer period of time, such as 24 hours.

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Note: The actual rebuild time can differ significantly from the time you specify, especially for a RAID-1_0 LUN, or a LUN containing 4 GB disk modules. Since a RAID-1_0 with n disk modules can continue functioning with up to as many as n/2 failed drive modules and only one drive at a time is rebuilt, the actual rebuild time for such a LUN is the time you specify multiplied by the number of failed drives. For 4 GB disk modules, the minimum rebuild time should be 2 hours, because a rebuild time of less than 2 hours actually takes about 2 to 3 hours. If you specify any other time, the actual rebuild time for the disk module is about twice as long.

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If the LUN you are creating is RAID-0, -1_0, or -5, use the Element Size text field to select a different number of sectors for the stripe element for the default (128 sectors).

The stripe element size is the number of disk sectors that the storage system can read or write to a single disk module without requiring access to another disk module (assuming that the transfer starts at the first sector in the stripe). The stripe element size can affect the performance of a RAID-5 or RAID-1_0 LUN. A RAID-3 LUN has a fixed stripe element size of one sector, a value that you cannot change.

The smaller the stripe element size, the more efficient the distribution of data read or written. However, if the stripe size is too small for a single I/O operation, the operation requires access to two stripes, which causes the hardware to read or write from two disk modules instead of one. Generally, you use the smallest stripe element size that rarely forces access to another stripe.

For the LUN to have a different default SP owner than that shown at Default SP, select the diamond-shaped radio button for the other SP.

The default SP assumes ownership of the LUN after the storage system's power is cycled. If the storage system has two SPs, you can choose to bind some LUNs using one SP and the rest using the other SP. Splitting the LUNs can balance the load across the SPs and establish the primary server for the LUN in a dual-server configuration. The primary route to a LUN is the route through the default SP, and the secondary route is through the other SP.

Disable auto-assign by deselecting the Auto Assign select button in the Assignment field. Disabling auto-assign is recommended for most uses, and is required if failover software is present.

Auto-assign controls the ownership of the LUN when an SP fails in a storage system with two SPs. With auto-assign enabled, if the SP that owns a LUN fails and the server tries to access that LUN through the second SP, the second SP assumes ownership of the LUN so that access can occur. The second SP continues to own the LUN until the SP's power is cycled (turned off and on again). When the power is cycled, ownership of each LUN returns to its default SP. If auto-assign is disabled in the previous situation, the other SP does not assume ownership of the LUN, so the access to the LUN does not occur.

For a LUN to be used in a high-availability configuration, auto-assign must be disabled. By default, auto-assign is disabled in RAID5GUI.

For any LUN except RAID-3 with RAID-3 memory assigned, click the button at Cache Enabled in the LUN Caching field to enable or disable caching. If the caching is enabled, click the button at Write Cache or Read Cache in the LUN Caching field to enable or disable write or read caching.

Whether or not you should use caching for a specific LUN depends on the LUN's RAID type. These fields are not available for fast RAID-3. See Table 4-2 for recommendations for using caching for the different RAID levels.

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Note: “Setting Cache Parameters” in Chapter 7 explains how to set other caching parameters.

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If you are binding a RAID-3 LUN, change the default memory size if desired. Divide the amount of RAID-3 memory you allocated for the SP (as explained earlier in “Assigning Memory for RAID-3 LUNs”) evenly between this LUN and other RAID-3 LUNs for this SP. For a failover system, take half the amount of RAID-3 memory you allocated for this SP and divide it among this SP's RAID-3 LUNs.

Once you have selected all the parameters for the LUN, select each disk module for the LUN by clicking on the select button that appears next to each disk module button. Follow the guidelines in Table 4-1 in “Planning the Bind,” earlier in this chapter.

Clicking on a select button selects the disk module; a heavy black border appears around the disk module button to show that it is selected. To select more than one disk module, hold down a <Shift> key and click the disk module's select button. To deselect a disk module button, click the disk module's select button again.

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Note: If you are creating a RAID-1_0 LUN, the order in which you select the modules is important. The first module you select is the first part of the mirror's primary image, the second module is the first part of the mirror's secondary image, the third module is the second part of the primary image, the fourth module is the second part of the secondary image, and so on for any other modules in the LUN. In other words, the first and second modules selected are a pair of peer image parts, the third and fourth modules are another pair of peer image parts, and so on. Figure 4-11 diagrams this scheme.

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Figure 4-11. Disk Module Selection for RAID-1_0 Mirror Image

The RAID5GUI Bind window displays a different color border for each pair of disk modules you select. The first and second modules you select have a red border, the third and fourth a blue border, and so on. Deselecting one disk module in a pair causes the other module in the pair to be deselected, so that both are no longer paired and are available.

For high availability, the modules in a pair must be on different SCSI buses. For highest availability and performance in a RAID-1_0 LUN, select modules on consecutive SCSI buses. For example, for a six-module LUN, select these modules in order: A0, B0, C0, D0, E0, and A1. Modules A0 and B0 are peers, C0 and D0 are peers, and E0 and A1 are peers.

When you have selected all disk modules for the LUN and the LUN parameters specify the values you want, click Bind.

The bind operation begins, and the borders around the buttons of the disk modules in the LUN disappear, along with their select buttons. In the Summary View window, the state of each disk module in the LUN changes from Unbound to Binding. Generally, binding takes about 15 to 60 minutes for 2 GB disk modules, depending on system traffic. When the bind operation is completed, the state of each disk module in the LUN changes to Ready.

Repeat steps 11 and 12 for the remaining LUNs you want to create.

If you are binding RAID-3 LUNs in a failover system, take half the SP's RAID-3 memory and divide it evenly between this SP's LUNs. The remaining half of this SP's memory covers failover for the other SP. See “Planning a RAID-3 Bind,” earlier in this chapter for more detail.

When a LUN is assigned to an SP, its state becomes Assigned; the state of its disk modules becomes Enabled when you use the SP that owns the LUN as the communications path to the chassis.

Verify that the LUNs are the way you want them; see “Getting Disk Group (LUN) Information” later in this chapter.