SSA RSM The Array View Resource Lists Component Exchange Contents

RAID 0 RAID 1 RAID 5 RAID 10 FAST W

The Array View lists the attributes of the selected array. The array members are shown with a summary of their attributes.

This help is divided into sections :


Common Attributes:
(Common to all RAID types)

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Additional 'Hot-spare' Attributes:
(Common to RAID 1, 5 & 10)
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All array types, except RAID 0, can make use of Hot-spare resources to further enhance the availability of the SSA subsystem.


Additional 'Hot-spare Pool' Attribute:
(IBM Advanced SerialRAID/X Adapter Only)
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With the IBM Advanced SerialRAID Adapter, all array types, except RAID 0, can make use of Hot-spare Pool resources. These pools further enhance the availability of the SSA subsystem.


Additional 'System (PC)' Attribute:
(System 'PC' Resources Only)
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RAID 0 Icon

Additional 'RAID 0' Attributes:

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Note:

RAID 0 arrays can consist of three to sixteen components. The larger the number of components, the more the data is spread across disks and performance is increased. The disadvantage of a large number of components is that as RAID-0 provides no redundancy and data is striped across all the member disks, the loss of a single disk results in the loss of more data.

RAID 0 attributes depend on which adapter created the array. Select your adapter from this list to view the relevant attributes.


RAID 0 Icon

Additional 'RAID 0' Attribute:

when created with the
IBM SSA RAID Adapter (LL03 and LL11)

RAID 0 Arrays created with this adapter have the following attribute. This is in addition to the common attributes outlined above.

Note:

The Block Size can only be 512 with this adapter.


RAID 0 Icon

Additional 'RAID 0' Attribute:

when created with the
IBM Advanced SerialRAID/X Adapter

RAID 0 Arrays created with either of these adapters have the following attribute. This is in addition to the Common attributes outlined above.


RAID 1 Icon

Additional 'RAID 1' Attributes:

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Note:

RAID 1 arrays can only consist of two components.

The attributes of your RAID 1 arrays will depend on the adapter that created the array. Select your adapter from this list to view the RAID 1 attributes your adapter will present.


RAID 1 Icon

Additional 'RAID 1' Attributes:

when created with the
IBM SSA RAID Adapter or the
IBM SSA RAID Cluster Adapter

RAID 1 Arrays created with either of these adapters will have the following attributes. These are in addition to the Common and Hot-spare attributes outlined above.

  • Initial Rebuild:
    Default:Off
    Supports:On, Off

    When Initial Rebuild is set to 'On', the array will initially be rebuilding and will copy the data from the first component to the second. If this bit set to 'Off', the array starts life with its contents undefined, and will immediately become non-degraded.

    This attribute can only be used at creation time, and cannot be subsequently be changed. This attribute also insists that the first component has less than or an equal number of data blocks as the second.

    With the Initial Rebuild bit set to 'On' and user data has yet to be written to the array, the same data will be returned by whichever member disk is read. If the attribute is 'Off', it is not guaranteed to always return the same data for the same block before that block contains user data.

    Note:

    It is recommended that the Initial Rebuild attribute is set to 'On', to avoid possible problems if applications depend on the same data returned before data is written. Note that this will incur some performance overhead while the array is being rebuilt.

  • Data Scrub Enabled:
    Default:Off
    Supports:On, Off

    When Data Scrub Enable is set to 'On', the array will, when it is non-degraded, verify in the background that all the data for the array on the member disks can be read without error. If an error is detected during this verification, the failing block on the disk is repaired by rewriting the data from the mirrored array member disk.

  • Data Scrub Rate:
    Default:24 (hours)
    Supports:6 to 48 (hours) in steps of 1

    The Data Scrub rate sets the time in hours for the period of a single pass of data scrubbing the array. The default time is 24 hours. The shorter time incurs more interference with processing requests but detects latent failures earlier.

  • Rebuild Priority:
    Default:50%
    Supports:1% to 100%

    A higher value will result in faster array rebuilds, but may reduce the performance of applications during the rebuild period. A lower value will result in slower array rebuilds, but may increase the performance of applications during the rebuild period.

  • Split Confirm:
    IBM SSA RAID Cluster Adapter Only
    Default:Off
    Supports:On, Off

    When Split Confirm is set to 'On', an array with only one member disk, and previously both member disks were not attached to this adapter, is not brought online and an SSA event is generated. This provides protection from a member disk being moved to another system and then being used whilst the other disk of a mirrored pair is still being used on the original system.


RAID 1 Icon

Additional 'RAID 1' Attributes:

when created with the
IBM Advanced SerialRAID/X Adapter

RAID 1 Arrays created with this adapter will have the following attributes. These are in addition to the Common and Hot-spare attributes outlined above. For further information see the help which explains Multiple Domains and Component Ordering.

  • Split Array Resolution:
    Default:Primary
    Supports:Primary, Secondary

    This attribute controls how the subsystem will react in the event of a split between the domains. When set to 'Primary', the normal setting, ONLY the Primary Domain will continue to operate when a split occurs. When set to 'Secondary' ONLY the Secondary Domain will continue when a split occurs.

    In use, if a split occurs due to the loss of the Primary Domain, all operation will stop. Changing the setting of this attribute to 'Secondary' will allow the secondary domain to continue to operate. This should only be done when you are sure that the other using system has lost access to and is not using the Primary Domain. If the fault has occurred in the SSA loop, for example a cable fault, and the other using system is still using the Primary Domain, both systems will be able to access the two domains independently which will result in unsynchronised data. Cluster Mode Only

  • Initial Rebuild:
    Default:Off
    Supports:On, Off

    When Initial Rebuild is set to 'On', the array will initially be rebuilding and will copy the data from the first component to the second. If this bit set to 'Off', the array starts life with its contents undefined, and will immediately become non-degraded.

    This attribute can only be used at creation time, and cannot be subsequently be changed. This attribute also insists that the first component has less than or an equal number of data blocks as the second.

    With the Initial Rebuild bit set to 'On' and user data has yet to be written to the array, the same data will be returned by whichever member disk is read. If the attribute is 'Off', it is not guaranteed to always return the same data for the same block before that block contains user data.

    Note:

    It is recommended that the Initial Rebuild attribute is set to 'On', to avoid possible problems if applications depend on the same data returned before data is written. Note that this will incur some performance overhead while the array is being rebuilt.

  • Rebuild Priority:
    Default:50%
    Supports:1% to 100%

    A higher value will result in faster array rebuilds, but may reduce the performance of applications during the rebuild period. A lower value will result in slower array rebuilds, but may increase the performance of applications during the rebuild period.

  • Invalid Data Strips:

    The number of data strips which are invalid.

  • Unbuilt Data Strips:

    The number of data strips remaining to be built.


RAID 5 Icon

Additional 'RAID 5' Attributes:

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Note:

RAID 5 arrays can consist of three to sixteen components. The larger the number of components, the worse the performance may be for long transfers. However, the larger the number of components, the greater the reduction in the overhead of the parity function. Therefore the available capacity is maximised by using a larger number of components.

RAID 5 attributes depend on the adapter that created the array. Select your adapter from this list to view the relevant attributes.


RAID 5 Icon

Additional 'RAID 5' Attributes:

when created with the
IBM SSA RAID Adapter

RAID 5 Arrays created with this adapter will have the following attributes. These are in addition to the common and the 'Hot-spare' attributes outlined above.


RAID 5 Icon

Additional 'RAID 5' Attributes:

when created with the
IBM SerialRAID Adapter or the
IBM Advanced SerialRAID/X Adapter

RAID 5 Arrays created with either of these adapters will have the following attributes. These are in addition to the common and 'Hot-spare' attributes outlined above.


RAID 10 Icon

Additional 'RAID 10' Attributes:

when created with the
IBM Advanced SerialRAID/X Adapter

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RAID 10 Arrays are only supported by the IBM Advanced SerialRAID/X Adapter. Such arrays have the following attributes in addition to the Common and the 'Hot-spare' attributes outlined above. For further information see the help which explains Multiple Domains and Component Ordering.

Note:

RAID 10 arrays can consist of four to sixteen components. The larger the number of components, the more the data is spread across disks and performance is increased. With a finite number of disks available for RAID 10 arrays, best performance is achieved with an equal number of RAID 10 arrays on each SSA loop.


Fast Write Icon

Additional 'Fast Write' Attributes:

when created with the
IBM SerialRAID Adapter or the
IBM Advanced SerialRAID/X Adapter

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Fast Write resources have the following Fast Write attributes in addition to the Common array, or Common disk attributes.


Actions:

Serial Number

Select any serial number to display the relevant Disk View.

Refresh

This action updates the current page.

Flash On

This action starts the flashing indicator light on all of the array components.
Note:

A message will be displayed in the Information Area indicating the resource is flashing. This message will appear only once. You must remember to Flash Off the resource, or the light will continue to flash. To clear all indicators, use the Flash All Off button on the Adapter View to Flash Off the indicator lights on all disks attached to the selected adapter.

Flash Off

This action stops the indicator light flashing on all of the array components.

Attach

This action changes the use of an array from 'Free' to 'System (PC)'. The array will then be available to the operating system. This action links to the Attach page, where a resource number is chosen. This number dictates the order in which resources are presented to the operating system.

'Free' Resources Only.

Detach

This action changes the use of an array from 'System (PC)' to Free. The resource will no longer be available to the operating system.

'System (PC)' Resources Only.

Delete

This action destroys the array and returns its component disks to the 'Free' usage class.

Create

This action will take you to the Create Array page. The default attributes will be assigned to the same values as the current array.

Modify Attributes

This action will take you to the Modify Array page where you can modify the relevant array's attributes.

Create FW

This action will take you to the Create Fast Write Array page. When complete, the array will use the Fast Write Cache for data writes.

'Free' Resources, and Fast Write Adapters Only.

Modify FW

This action will take you to the Modify Fast Write Array page where you can modify some of the current array attributes.

'Free' Resources, and Fast Write Adapters Only.

Delete FW

This action will stop the array using the Fast Write Cache Feature for data writes.

'Free' Resources, and Fast Write Adapters Only.

Assign Hot-spare pool

This action allows you to assign or modify the Hot-spare P that ALL of the array components will be protected by. A JavaScript text entry pop-up will be displayed. Enter the new Pool number.

IBM Advanced SerialRAID/X Adapter Only


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