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There are two different ways to configure the SCSI reservation agent resource and the shared disk agents resource. It depends on the attribute of the SCSI reservation agent resource.
1. When shared disk and SCSI Lock resource is configured with the same LUN (PrType=1)
In the SCSI reservation agent resource, use the option of PrType = 1. In this case, LUN will be used to configure the shared disk resource and the SCSI reservation resource.
A shared disk agent uses the MVL driver to manage DATA-DISK and a SCSI reservation agent uses the SCSI3-PR function to manage LOCK-DISK.
By setting the dependency between the SCSI reservation resource and the shared disk resource, you can prevent damages to DATA-DISK caused by Split-Brains and so on.
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[Figure] Shared disk and SCSI Lock resource configured in same LUN (PrType=1)
2. Shared disk and SCSI lock resource is configured with different LUN (PrType=3)
A shared disk agent manages DATA-DISK on the single drive character basis, and a SCSI reservation agent manages the standalone LUN exclusively for LOCK-DISK.
For this configuration, there must be at least two LUN segments existing on the shared disk.
As shown below, create the LOCK-DISK volume that will depend on a shared disk agent in a 1:1 relationship.
By using multiple shared disk agents, and one SCSI reservation agent, you can configure the dependency for use.
This disk with small capacity is allowed because it is used to check the node that can access the storage.
By setting the dependency between the SCSI reservation resource and the shared disk resource, you can prevent damages to DATA-DISK caused by Split-Brains and so on.
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[Figure] Shared disk and SCSI Lock resource is configured with different LUN( PrType=3)
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Attribute | Description | Type | Default | Edit | Note |
| DiskDUID | DUID(Device Unique ID, 16 byte as Hex value) of disk is used as identifier. Specify DUID of reserve disk. | STRING | X | ||
| DriveLetter | Disk to be used for reservation is specified by drive letter. | STRING | X | ||
| Key | MAC address is used as Reserved-Key. This key is automatically set by agent. | STRING | |||
| PreemptWaitCount | Time waiting for permission of other node before reservation | INTEGER | 2 times | O | |
| PrType | This attribute decides on how to give the permission of reserve disk access as Persist Type specified in SCSI3-PR spec. | INTEGER | Prtype=1 | O |
scsicmd.cmd Command
Syntax
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scsicmd [option] [diskID] |
Option
This is the utility to use SCSI 3 PR command more easily. Following is the provided options
Option | Description |
-c diskId | It deletes Reserved-Key and Registered-Key of local node of disk. |
-cf diskId | It forcely deletes Reserved-Key and Registered-Key of local node of disk. |
| -r diskId | Registers diskld-specified disk. |
-l diskId | If node is yet to reserve, close the specified disk and reserve. |
-lf diskId | It forcelu closes specified disk and reserve, even node has been reserved. |
| -h | It shows help of scsicmd. |
no option | It shows the state information regarding disk reservation when there is no other option. |
Print Sample
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The output of 'scsicmd' command from source node (C29043F13 is MAC Address of NIC from source node.)
The output of 'scsicmd' command from target node (C29043F13 is MAC Address of NIC from source node.)
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