This page allows you to modify some of the array attributes.
This help is divided into sections :
- RAID Attributes
( Select the RAID type below )
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RAID-1
|
Data Mirroring
2 member disks. |
 |
RAID-5
|
Data Striping with Parity
3 to 16 member disks. |
 |
RAID-10
|
Mirrored Data Striping
4 to 16 member disks, in steps of 2. |
 |
Fast Write Arrays
|
Arrays which use the Fast Write Cache Feature
(RAID-10 Fast Write Array Shown) |
- Hot-spare Attributes
( RAID-1, 5 & 10 )
- Hot-spare Pool Attributes
( RAID-1, 5 & 10 created on the
Advanced SerialRAID/X Adapter Only )
Additional 'Hot-spare' Attributes:
(Common to RAID-1, 5 & 10) |
 |
All array types, except RAID-0, can make use of
Hot-spare resources to further enhance the availability
of the SSA subsystem.
Hot-spare Exact Size:
Default: | Off |
Supports: | On, Off |
When Hot-spare exact is set to 'On', only Hot-spares of exactly
the same size as the failing disk will be used. When Hot-spare exact is
'Off', the Hot-spare used may have a greater capacity than the failing
disk it is replacing.
 |
Additional 'Hot-spare Pool' Attributes:
(IBM Advanced SerialRAID/X Adapter Only) |
 |
With the 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.
-
Hot-spare Splits:
Default: | Off |
Supports: | On, Off |
When Hot-spare Splits is set to 'On', and only one half of the RAID-10,
or RAID-1 array is available for use; Hot-spare
disks will still be used, if required, from the chosen or available pools.
When Hot-spare Splits is set to 'Off', hot-spare disks will not be used if
only one half of the RAID-10, or RAID-1 array is available.
- Minimum Number of Hot Spares in Pool:
This is the minimum number of hot spare disks that can be
available in this pool before an error is raised.
Hot-spare Preferred:
Default: | Off |
Supports: | On, Off |
When Hot-spare Preferred is set to 'On', only a hot-spare from the
preferred Hot-spare pool will be used to replace a failing disk. When
Hot-spare preferred is 'Off', a suitable Hot-spare from a Hot-spare pool
other than the preferred pool may be used to replace a failing disk if
the preferred Hot-spare pool is empty. Pool 0 will be tried first, then
any other available pools.
Note: |
If Hot-spare preferred is 'On', Hot-spare disks in the global
pool 0 will not be used. |
 |
Additional 'RAID-0' Attributes:
|
 |
Note: |
RAID-0 arrays do not have any attributes that can be modified. |
 |
Additional 'RAID-1' Attributes:
|
 |
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.
 |
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
Hot-spare attributes outlined above.
-
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.
 |
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
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
-
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.
 |
Additional 'RAID-5' Attributes:
|
|
 |
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 which adapter created the array.
Select your adapter from this list to view the relevant attributes.
 |
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
'Hot-spare' attributes outlined above.
-
Strip Size:
Default: | 128 |
Supports: | 128 Only |
This defines the number of contiguous blocks held on a disk before
switching to the next disk. Larger values may result in worse performance
for long transfers as the data may be striped across fewer disks. Lower
values can result in worse performance for writes but incur a longer
rebuild time when a failed component is replaced..
-
Stretch Size:
Default: | 4 |
Supports: | 1 to 9999 in steps of 1. |
This is the number of strips before the disk that holds the
parity data is changed. The default value is 4 and there is nothing to be
gained by using any other value.
-
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.
 |
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
'Hot-spare' attributes outlined above.
-
Strip Size:
Default: | 128 |
PC Supports: | 32, 64, 128 |
This defines the number of contiguous blocks held on a disk before
switching to the next disk. Larger values may result in worse performance
for long transfers as the data may be striped across fewer disks. Lower
values can result in worse performance for writes but incur a longer
rebuild time when a failed component is replaced.
-
Stretch Size:
Default: | 4 |
Supports: | 1 to 9999 in steps of 1. |
This is the number of strips before the disk that holds the
parity data is changed. The default value is 4 and there is nothing to be
gained by using any other value.
-
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.
 |
Additional 'RAID-10' Attributes:
when created with the
IBM Advanced SerialRAID/X Adapter |
 |
RAID-10 Arrays are only supported by the
Advanced SerialRAID/X Adapter. Such arrays have the following
attributes in addition to 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. |
-
Strip Size:
Default: | 32 |
Supports: | 32, 64, 128 |
This defines the number of contiguous blocks held on a disk before
switching to the next disk. Larger values may result in worse performance
for long transfers as the data may be striped across fewer disks. Lower
values can result in worse performance for writes but incur a longer
rebuild time when a failed component is replaced..
-
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
-
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.
 |
Additional 'Fast Write' Attributes:
when created with the
IBM SerialRAID Adapter or the
IBM Advanced SerialRAID/X Adapter |
 |
See the Fast Write Attributes in
the array view help.
Actions:
Modify |
This action submits the modified attributes.
Note: |
Some modifications may cause the array to start rebuilding. |
|
Cancel |
This action aborts the array modification, and returns to the
relevant Array View. |
Related Information