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SCSI-Lock resource can be configured in 2 ways with shared disk resource. Configuration process changes according to the attribute value of SCSI Lock resource.
1. When shared disk and SCSI Lock resource is configured with the same LUN (PrType=1)
When you define an attribute of SCSI Lock resource as PrType=1, you can configure shared disk and SCSI Lock resource with the same LUN.
SCSI Lock agent manages DATA-DISK(shared disk resource) using by MOUNT/UMOUNT command and manages LOCK-DISK(SCSI Lock resource) using by SCSI-3 PR as shown below.
By setting up the dependency between SCSI Lock resources and shared disk resources, any damage of data-disk can be prevented which may occur in such case like Split-Brain.
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[Figure] Shared disk and SCSI Lock resource configured in same LUN (PrType=1)
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At this type, shared disk agent manages DATA-DISK where user data is stored and SCSI lock agent uses exclusive LUN for key reservation. Therefore, two LUNs is required at least.
Lock-disk volume is created for 1:1 dependency with shared disk agent like a figure below.
By using multiple shared disk agents, and one SCSI reservation agent, you can configure the dependency relationship for use.
The storage capacity of this disk can be small 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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1. Shared disk and SCSI Lock resource is configured in same LUN (PrType = 1)
[Figure] Shared disk and SCSI Lock resource configured in same LUN
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2.Shared disk and SCSI Lock resource configured with different LUN (PrType = 3)
[Figure] Shared disk and SCSI Lock resource configured with different LUN
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- When add a resource from a group name, select a group → right click → 'Add Resource'.
[Figure] Adding Resource in a group - Select 'SCSILOCK' from Resource Type lists and click 'Next' button.
[Figure] Select Resource Wizard View - Next steps are same as adding in resource type.
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- ResourceType → Right Click → Click Add Resource
[Figure] Adding Resource in a resource type - If all the information is retrieved, you can select a device path used as the SCSI reservation resource.
[Figure] Selecting driver letter View - When there is no disk for SCSI Lock resource, "Disk Not Found" message appears.
[Figure] Disk Not Found - If you select a device path used for the SCSI reservation resource, a name will be automatically recommended.
[Figure] Select device path - Click 'Finish' and SCSI Lock resource is added.
[Figure] Adding SCSI Lock resource is completed
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- Select "Delete Resource".
[Figure] Delete SCSI Lock resource view
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| Status | Agent command | Description | Note |
|---|---|---|---|
Online Disk key is exclusively reserved at an online node. | Offline | It ignores the reservation key stored. It first creates a new reservation key and switches to offline while maintaining the reservation. | |
| Monitoring | Compares the key reserved in the disk and check if there is a reservation made on the disk. | ||
Offline 1. Disk is reserved but the resource is still offline. | Online | Register a key for a disk reservation and wait for a response from the other node. After going online once, the other node reservation is stolen. This is called preempt. | |
| Monitoring | Compares the key reserved in the disk and check if there is a reservation made on the disk. | ||
Trouble It occurs when a reservation is stolen while going online. | Online | Register a key for a disk reservation and wait for a response from the other node. After going online once, the other node reservation is stolen. This is called preempt. | |
| Offline | It ignores the reservation key stored. It first creates a new reservation key and switches to offline while maintaining the reservation. |
Attribute
[Figure] SCSI Lock Attribute view
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