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Changing Controller Parameters

Use this option to modify the parameters for the array controller.

  1. Select the appropriate array controller from the main window.
  2. Select Configuration > Custom Configure. If necessary, log into the configuration level of the program with the ssconfig password.
  3. From the Custom Configuration Options window, select Change Controller Parameters. The Change Controller Parameters window with the Channel tab is displayed.
  4. Controller Name. If the controller name needs to be set, select Controller Name and type the desired name. Click OK to save the change.

    Controller Unique ID. The Controller Unique ID is automatically set.

The tabs in this window include:

Channel Tab

RS 232 Tab

Cache Tab

Disk Array Tab

Drive I/F Tab

Host I/F Tab

Redundancy Tab

Network Tab

Some of the options on the Change Controller Parameters window require that the controller be reset so the changes can take effect. For details about saving changes in the Change Controller Parameters window, see Saving Changed Values.

Channel Tab

  1. From the Channel tab, select the channel to be edited.
  2. Click Change Settings.
  3. The Change Channel Settings window is displayed. For the server to recognize the array, a host channel must have an ID assigned to a logical drive and a logical drive mapped to that host channel and ID. This window enables you to configure the host/drive channel.

  4. From the Channel Mode list box, select either Host or Drive. A Drive channel is what the drives are connected to (internal or external). A Host channel is what is connected to the server.

  5. NOTE: Depending on the controller configuration, you might need to select both primary and secondary channel IDs as described in the following steps.

  6. From the Available SCSI IDs list box, first select the primary channel ID, which is designated as PID. Then click Add PID.
  7. If you have two controllers installed, select a secondary channel ID from the Available SCSI IDs list box, and click Add SID.

  8. For changes to take effect, reset the controller.

Changing Host ID in a Fibre Configuration

  1. If you want an ID higher than 15, click Select SCSI ID Range and select the desired range.

    NOTE: Each channel's ID must be within the same range.

  2. Click Remove to remove the PID or SID.
  3. Once your selections have been made, click OK to redisplay the previous window.

RS 232 Tab

  1. After all channel settings have been made, from the Change Controller Parameters window, select the RS 232 Settings tab.
  2. Select the port desired, and click Change Settings. The Change RS232 Port Settings window is displayed.
  3. Select any baud rate desired including the default rate of 9600, and click OK to return to the previous window.

Cache Tab

From the Cache tab, you can select the optimization mode for the logical drive, which indicates the amount of data that is written across each drive in an array. Sequential I/O indicates large blocks of data. Random I/O indicates small blocks of data. The following table specifies the stripe sizes for each RAID level, depending on the optimization mode.

RAID Level Sequential I/O Random I/O
0, 1, 5 128 32
3 16 4

The type of application the array is working with determines whether Random or Sequential I/O should be applied. Video/imaging application I/O size can be 128, 256, 512 Kbyte, or up to 1 Mbyte, so the application reads and writes data to and from the drive as large-block, sequential files. Database/transaction-processing applications read and write data from the drive as small-block, randomly-accessed files.

There are two limitations that apply to the optimization modes:

  • One optimization mode must be applied to all logical drives in an array.

  • Once the optimization mode is selected and data written to logical drives, the only way to change the optimization mode is to back up all data to another location, delete all logical configurations of drives, reconfigure the logical drive with the new optimization mode, and reboot the array.
  • NOTE: The maximum allowable size of a logical drive optimized for Sequential I/O is 2 Tbyte. The maximum allowable size of a logical drive optimized for Random I/O is 512 Gbyte. When creating a logical drive that is greater than these limits, an error message is displayed.

    See also Write-Back Cache and Maximum Number of Disks and Maximum Usable Capacity for Random and Sequential Optimization.

  1. From the Change Controller Parameters window, select the Cache tab.
  2. Select Optimization from the list box or accept the current setting.

    This option indicates the amount of data that is written across each drive in an array. Sequential I/O indicates large blocks of data; random I/O indicates small blocks of data.

  3. If an existing logical drive was created with Optimization set for Random I/O, the same logical drive is not be capable of reading or writing data when changed to sequential mode. The reverse is also true because the stripe size is different for each.

  4. To utilize Write Back, click the list box and select either Enables or Disabled.

Disk Array Tab

  1. From the Change Controller Parameters window, select the Disk Array tab. Four list boxes are displayed.
  2. Select either Disabled or Enabled from the three Write Verify list boxes.
  3. Normally, errors might occur when a hard drive writes data. To avoid the write error, the controller can force the hard drives to verify the written data.

    • Write Verify on Initialization - performs verify-after-write while initializing the logical drive.
    • Write Verify on Rebuild - performs verify-after-write during the rebuilding process.
    • Write Verify on Normal - performs verify-after-write during normal I/O requests.


  4. Select from the four options available in the Rebuild Priority list box: Low, Normal, Improved, or High.
  5. The RAID controller provides a background rebuilding ability. This means the controller is able to serve other I/O requests while rebuilding the logical drives. The time required to rebuild a drive set largely depends on the total capacity of the logical drive being rebuilt. Additionally, the rebuilding process is totally transparent to the host computer or the operating system.

    • Low - the default that uses the controller's minimum resources to rebuild
    • Normal - to speed up the rebuilding process
    • Improved - to allocate more resources to the rebuilding process
    • High - to use the controller's maximum resources to complete the rebuilding process in the shortest time possible

Drive I/F Tab

  1. From the Change Controller Parameters window, select the Drive I/F tab.
  2. From the SCSI Motor Spin Up field, select either Disabled or Enabled.
  3. The SCSI Motor Spin-Up decides how the SCSI drives in a Disk Array are started. When the power supply is unable to provide sufficient current for the hard drives and controllers that are powered up at the same time, spinning up the hard drives serially is one of the best ways to consume lower powerup current. By default, all hard drives spin up when powered on.

  4. From the Power Up SCSI Reset field, select either Enabled or Disabled.
  5. By default, when the controller is powered up, it sends a SCSI bus reset command to the SCSI bus. When disabled, it does not send a SCSI bus reset command on the next power up.

    When connecting dual host computers to the same SCSI bus, the SCSI bus reset interrupts all the read/write requests being performed. This might cause some operating systems or host computers to act abnormally. Disable Power Up SCSI Reset at power up to avoid this situation.

  6. Set the Disk Access Latency.
  7. This function sets the delay time before the controller tries to access the hard drives after power on. The default is 15 seconds.

  8. Set the Tag Count Per Drive.
  9. This is the maximum number of tags that can be sent to each drive at the same time. A drive has a built-in cache that is used to sort all of the I/O requests (tags) that are sent to the drive, enabling the drive to finish the requests faster.

    The cache size and maximum number of tags varies between different brands and models of drive. Use the default setting of 32. Changing the maximum tag count to Disable causes the internal cache of the drive to be ignored (not used).

    The controller supports tag command queuing with an adjustable tag count from 1 to 128.

  10. From the SAF-TE Polling Period (Sec.) field, select the variable time options shown in the list box, or select 0.0 to disable this function so that all installed Event Recording Modules (ERMs) are never polled.
  11. From the SCSI I/O Timeout (Sec) field, select from 0.5 through 30 seconds.
  12. The SCSI I/O Timeout is the time interval for the controller to wait for a drive to respond. If the controller attempts to read data from or write data to a drive but the drive does not respond within the SCSI I/O timeout value, the drive is considered a failed drive.

    The SCSI I/O Timeout is the time interval for the controller to wait for a drive to respond. If the controller attempts to read data from or write data to a drive but the drive does not respond within the SCSI I/O timeout value, the drive is considered a failed drive.

    The default setting for SCSI I/O Timeout is 15 seconds for the SCSI array and 30 seconds for the Fibre Channel array.

    CAUTION: Do not change this setting. Setting the timeout to a lower value causes the controller to judge a drive as failed while a drive is still retrying or while a drive is unable to arbitrate the SCSI bus. Setting the timeout to a greater value causes the controller to keep waiting for a drive, and it might sometimes cause a host timeout.

    When the drive detects a media error while reading from the drive platter, it retries the previous reading or recalibrates the head. When the drive encounters a bad block on the media, it reassigns the bad block to another spare block. However, all of this takes time. The time to perform these operations can vary between different brands and models of drives.

    During SCSI bus arbitration, a device with higher priority can use the bus first. A device with lower priority sometimes receives a SCSI I/O timeout when devices of higher priority keep using the bus.

  13. From the Drive Check Period (Sec) field, select from 0.5 through 30 seconds.
  14. The Periodic Drive Check Time is an interval for the controller to check the drives on the SCSI bus. The default value is Disabled, which means if there is no activity on the bus, the controller does not know if a drive has failed or has been removed. Setting an interval enables SANscape to detect a drive failure when there is no array activity; however, performance is downgraded.

Host I/F Tab

  1. From the Change Controller Parameters window, select the Host I/F tab.
  2. Set the Max Queued IO Count.
  3. This function enables you to configure the maximum size of the I/O queue the controller can accept from the host computer by byte size. The default is 256. The predefined range is from 1 to 1024 bytes, or you may choose the Auto Computer (Automatically Configured) mode.

  4. Set the LUNs Per Host.
  5. This function is used to change the number of LUNs per host SCSI ID. The default setting is 32 LUNs, with a predefined range of 1 to 32 LUNs available.

  6. For changes to take effect, reset the controller.

Redundancy Tab

  1. From the Change Controllers Parameter window, select the Redundancy tab.
  2. Three information-only fields are displayed: Controller Configuration, Controller Status, and the Secondary Serial No. fields.

  3. Select an option from the Set Controller Config field.
    • Redundant Deassert Reset - if you have failed a controller and want to bring it back online.
    • Redundant Force Sec Fail - if you want to force the secondary controller to fail.
    • Redundant Force Pri Fail - if you want to force the primary controller to fail.

    NOTE: Set both controllers in the Redundant Primary configuration. The controllers then determine which one is primary and which one is secondary. This prevents any possible conflicts between controllers.

  4. To save any changes in the Change Parameters window, select the Issue Controller Reset.
  5. Click Close to return to the main window.

Network Tab

  1. From the Change Controllers Parameter window, select the Network tab.
  2. To manually configure an IP address, subnet mask, gateway, and MAC address, click Change Settings.
  3. If you have set up an array in an environment with a DHCP Server, you can select Enable Dynamic IP Assignment to enable the array to automatically obtain an IP address from the network.

Saving Changed Values

Some of the options on the Change Controller Parameters window require that the controller be reset so that the changes take effect. If a change requires a controller reset, the following message is displayed in the lower left side of the window:

[Controller reset is required for changes to take effect.]

To reset the controller and save changed values, you can either select the Issue Controller Reset check box at the time of making the change, or reset the controller later through the Controller Maintenance window. If you are making multiple changes, you might not want to stop and reset the controller after each change. If you do not select the Issue Controller Reset check box, and the change requires a reset, when you click OK, a warning message is displayed.

  1. Select the Issue Controller Reset check box.

  2. Make the changes and click OK.
or
  1. Do not select the Issue Controller Reset check box.

  2. Make the changes and click OK.

  3. Reset the controller later.
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