SSA RSM Create Array Disk View Create Array - Candidates Contents

RAID-0 RAID-1 RAID-5 RAID-10 FAST W


There are two steps which must be completed when creating a new array.

  1. Define the array attributes - attributes are adapter and array specific. All attributes are explained below.

  2. Selecting the array members - the candidate disks are 'Free' disks which possess the relevant attributes as defined in step 1.

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' Attributes:
(IBM Advanced SerialRAID/X Adapter Only)
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With the Adanced 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.

Note:

When assigning a Hot-spare Pool to protect an array, please ensure the pool contains the correct capacity of resources as the array. i.e. the pool contains resources with the same or greater capacity as the array member resources.


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. A 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 should normally be set to 'Primary' When it is set to 'Secondary', the system only needs access to the secondary domain to continue operation if it has lost access to the other using system and the primary domain. This should only be set to 'Secondary' when you are sure that the other using system has lost access to and is not using the Primary Domain. If the fault has occured 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 independantly 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.


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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See the Fast Write Attributes in the array view help.


Actions:

OK

This action submits the attributes and displays a list of suitable candidates.

Auto

This action create a new array, with the chosen attributes. You will not be asked to select the components from the candidate list, the first n appropriate 'Free' disks will be chosen - where n is the number of components in the array. All disks will be the same size - if possible. When Auto is selected on IBM Advanced SerialRAID/X Adapter, the array will be assigned to the global hot-spare pool on the given SSA Loop, that is either pool A0 or B0 - unless this pool does not exist, when the lowest numbered available pool is used. If no hot-spare pools exist, the global pool will be created and the array assigned to this pool.

Cancel

This action aborts the array creation, and returns to the relevant Resource List.

Confirm

IBM Advanced SerialRAID/X Adapter Only
This action displays the RAID-10 Confirmation page. If you have chosen to create your RAID-10 array using multiple domains this page allows you to check that you have assigned the resources to the correct domain. You can flash the indicator lights on either half of the array as part of this confirmation.


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