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SSA RSM Tutorial - RAID-10 and the Hot-Spare Manager

NB - Do not click any of the "action buttons" on this page as they do nothing! The forms are shown here to provide an example of how the pages look.

This section provides a simple step through of the processes involved in configuring :

(IBM Advanced SerialRAID/X Adapter Only)


Creating a Hot-Spare Pool.

To create a Hot-Spare Pool, go to the Logical View and select the Hot-Spare Pools list. Then click "Create Hot-Spare Pool". You will be presented with a form as shown here :


Hot-spare

SSA Create Hot-spare

ATTRIBUTES

S8390080

Block size INFO. bytes
Network ID INFO.
Hot-spare Pool NumberValue limits: Min value: 0, Max value
: 31, Step value: 1
Minimum Number of Hot-spares In PoolValue limits: Min value: 1, Max value: 48, Step value: 1


Select Network ID, which loop this pool will be able to protect, the pool number ( RSM will automatically default to the next available pool number on the chosen loop. Selecting another loop may result in the pool number changing automatically ), and the minimum number of hot-spare disks that may be present before and error is raised. When complete, select "OK". You will then be presented with the candidate selection form.


Hot-spare

SSA Create Hot-spare

CANDIDATES

S8390080

Block size 512 bytes
Network ID B
Hot-spare Pool is synchronised on
Hot-spare Pool Number 2
Number of Hot-spares In Pool (Actual) 0
Hot-spares In Pool (Configured) 0
Minimum Number of Hot-spares In Pool 1

Select resources 1 ... 11
  Location Serial number Status Size Network ID
RSM1-1 29C8CF47 Online 9.1 GB B
RSM1-2 29C8A881 Online 4.5 GB
RSM1-3 29C8CE2F Online 9.1 GB
RSM2-1 29D034D8 Online 4.5 GB
RSM2-2 29D03626 Online 4.5 GB


The attributes chosen in step1 are shown above a table of suitable Hot-Spare candidate disks. These are disks that are either free or are Hot-spare resources which have defaulted to pool0. Select the disks you wish to add to this pool, that is, those disks that will become Hot-Spare disks which can be used by this pool. When you are finished select "Create". You will be returned to the Hot-Spare Pool List, where the newly created pool will be listed as 'unused'. Follow the RAID-10 Tutorial below to use the pool to protect array members.

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Adding Hot-spare Disks to a Pool

To add a Hot-spare Disk to a Pool, select the Logical View, then Hot-Spare Pools to view the Hot-Spare Pool List. From here, select the Pool you wish to add a new Hot-Spare disk to. On the Hot-Spare Pool View, select the action "Add". You will be presented with a Candidate List, where you can select which disk you wish to add to the pool of Hot-Spares. The Candidate List is identical to that shown above.

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Creating a RAID-10 Array with Multiple Domains

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.

RAID 10 - Component Order

When you are creating a RAID 10 array, you can also assign the Component Order. This allows you to control which candidates will become mirrored pairs within the array.

RAID 10 uses mirrored stripe sets, where the data is striped across a set of drives (The stripe set). At the same time, the stripe set is mirrored to another set of disks. Using this method of redundancy allows multiple domains to be created within one array.

RSM provides component ordering to allow you to create two domains within an array which has an even number of component disks, or members. Each domain contains a copy of the entire stripe set. One domain is assigned as the Primary, the other being the Secondary. As long as the Primary Domain is accessible, the array can continue to process read and write requests, even if the Secondary Domain has been lost.

Consider when assigning the array component order if multiple domains are to be used. For example, you can physically separate one domain from the other. i.e. in a different enclosure, in a different building and so on. Thus, power failing in one enclosure, or building will not take the array offline.

NOTE: The secondary domain will be prevented from continuing if it loses contact with the primary domain and the Split Resolution attribute is set to 'Off'.

NOTE: If you do not wish to use multiple domains leave the component order as 'default'

The first step is to select the RAID-10 array attributes. Select RAID-10 from the Logical View. Then select the "Create Array" action, you will be presented with this form:


RAID 10

SSA Create array

ATTRIBUTES

S9155043

Resource name Number of components

Block sizeINFO. bytes
Strip sizeINFO.
Hot-spare enabledINFO.
Hot-spare exact sizeINFO.
Hot-spare splits
Initial rebuild INFO.
Split resolution
Rebuild priority Value limits: Min value: 1%, Max value: 100%, Step value: 1% %
Network IDINFO.
Hot-spare PreferredINFO.


Complete the form as is required, for help relating to each attribute, see the context sensitive help page - select the help icon on the relevant page. Select "OK" to proceed to select the disks that will become members of this array. Select "Auto" to let RSM select the first N available candidates and automatically create the array. If you select "OK" you will be presented with the following form:


RAID 10

SSA Create array

CANDIDATES

S9072115

Resource name Your_R10_Array
Number of components 4

Block size 512 bytes
Strip size 32
Hot-spare enabled on
Hot-spare exact size off
Hot-spare splits off
Initial rebuild off
Split resolution off
Rebuild priority 50 %
Network ID A
Invalid data strips 0
Unbuilt data strips 0
Hot-spare Preferred off

Select components 4
  Pool ID Component Order Location Serial number Status Size Network ID
MAK8-14 AC7AD183 Online 9.1 GB A
MAK8-13 AC7AD185 Online 9.1 GB
MAK8-12 AC7AD197 Online 9.1 GB
MAK8-9 AC7AD153 Online 9.1 GB

Select the checkboxes beside each candidate disk that you wish to become a member of the array. At this point you can also assign which Hot-Spare pool will protect each individual array member. The component ordering, as described above, should be selected, assuming you wish to create the array and control the pairing with the array.

RSM component ordering allows you to pick the candidates that will become members of each domain if the following rule is followed :

The data written to the disk 'X (Primary)' is always mirrored on 'X (Secondary)' - where X is any value between 1 and 8.

When finished, select "Create" to go ahead and create the array with the candidates and component ordering as selected. If you wish to confirm that you have assigned the correct component ordering, select "Confirm" and you will be presented with the confirmation screen below :

Create array
Your_R10_Array

SSA Create array

Confirm

S9155043

Resource name Your_R10_Array
Number of components4

Mirroring will occur between the Primary and Secondary resources as listed below. You can correct the mirroring by modifying the Component Order values below. (Press 'Refresh' to check the result)

Primary resourcesSecondary resources
Component OrderSerial numberLocationmirrored withComponent OrderSerial numberLocation
29CCC0A4 TFXX-5 AC7AE55C TFXX-7
29CCC16E TFXX-6 AC7AE55E TFXX-8


You can start the indicator lights on all disk assigned to each domain to confirm that you have assigned the correct component ordering. Select "Flash All Off" to stop ALL indicator lights. You can also modify the ordering, should you have made a mistake. You must select "Refresh" after such modification to ensure the correct indicator lights are started. When you have finished, select "Create" to complete the creation.

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Adding / Changing the Hot-Spare Pool assignments

When an array has been created, you can modify the Hot-Spare pool that is protecting each array component. From the relevant array view, select the component you wish to modify. On the disk view for the selected component, select "Assign Hot-spare Pool". A Popup window is presented where you can change the value to the pool number you wish to protect this component.

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