5. DESCRIPCIÓN DEL SISTEMA
5.2. DIAGRAMA CAUSA-EFECTO
system requires a snapshot virtual disk repository for each member of the consistency group to provide the host application with WRITE access to a copy of the data contained in the snapshot image. You can create the repository automatically using the default settings or you can manually create the repository by defining the capacity settings for the repository.
You are initially creating an overall repository with one individual repository virtual disk. However, the overall repository can contain multiple repository virtual disks in the future for expansion purposes.
Use the Consistency Group Snapshot Virtual Disk Repository Settings - Manual option to manually
define the capacity requirements for a consistency group snapshot virtual disk repository. The Manual method is considered advanced and only those who understand physical disk consistency, provisioning, and optimal physical disk configurations should use this method.
The following guidelines apply:
• There is a minimum required capacity for a snapshot virtual disk repository (depending on your configuration).
• When you define the capacity requirements for a repository, keep in mind any future requirements that you may have for other virtual disks in this disk group or disk pool. Make sure that you have enough capacity to meet your data storage needs, but you do not over allocate because you can quickly use up all the storage in your storage array.
• The list of repository candidates can contain both new and existing repository virtual disks. Existing repository virtual disks are left on the storage array by default when you delete a consistency group snapshot virtual disk. Existing repository virtual disks are placed at the top of the list. The benefit to reusing an existing repository virtual disk is that you can avoid the initialization process that occurs when you create a new one.
To create a consistency group snapshot virtual disk repository:
1. From the AMW, select the Storage & Copy Services tab.
2. Select the consistency group to which you want to add member virtual disks and then select Copy
Services → Consistency Group → Remove Member Virtual Disks.
The Consistency Group Snapshot Virtual Disk Settings window is displayed.
3. Select Manual and click Next to customize the repository candidate settings for the consistency
group.
The Consistency Group Snapshot Virtual Disk Repository Settings - Manual window is displayed.
4. Select how you want filter the repository candidates for each member virtual disk in the consistency
group, based on either a percentage of the base virtual disk capacity or by preferred capacity. The best repository candidate for each member virtual disk based on your selections is displayed.
5. Select Edit individual repository candidates if you want to edit repository candidates for the
member virtual disks.
6. Select the repository, from the Repository candidates table, that you want to use for each member
virtual disk in the consistency group.
Select a repository candidate that is closest to the capacity you specified.
• The Repository candidates table shows both new and existing repositories that are capable of
being used for each member virtual disk in the consistency group based on the value you specified for percentage or the value you specified for preferred capacity.
repository candidates, and those with different Data Service (DS) attributes. If appropriate
candidates are not returned using these settings, you can click Run Auto-Choose to provide
automatic candidate recommendations.
• The Difference column shows the mathematical difference between your selected capacity and
the actual capacity of the repository candidate. If the repository candidate is new, the system uses the exact capacity size that you specified and displays zero (0) in the Difference column.
7. To edit an individual repository candidate:
a. Select the candidate from the Repository candidates table and click Edit to modify the capacity
settings for the repository. b. Click OK.
8. In the % full box, define the value that determines when a warning is triggered when the capacity of a
consistency group snapshot virtual disk repository reaches the defined percentage.
9. Click Finish to create the repository.
Disabling A Snapshot Virtual Disk Or Consistency Group Snapshot Virtual
Disk
Use the Disable option when you want to invalidate a snapshot copy or a consistency group snapshot
virtual disk. If the snapshot virtual disk or consistency group snapshot virtual disk is designated as read- write, this option also allows you stop any further write activity to its associated snapshot repository virtual disk.
Use the Disable option if one of these conditions applies:
• You are finished with the snapshot virtual disk or consistency group snapshot virtual disk for the time being.
• You intend to re-create the snapshot virtual disk or consistency group snapshot virtual disk (that is designated as read-write) at a later time and want to retain the associated snapshot repository virtual disk so that it does not need to be created again.
• You want to maximize the storage array performance by stopping write activity to the snapshot repository virtual disk.
If you decide to re-create the snapshot virtual disk or consistency group snapshot virtual disk, you must choose a snapshot image from the same base virtual disk.
If you disable the snapshot virtual disk or consistency group snapshot virtual disk, the system performs the following actions:
• Retains the World-Wide Name (WWN) for the snapshot virtual disk or consistency group snapshot virtual disk.
• Retains the snapshot virtual disk or consistency group snapshot virtual disk’s association with the same base virtual disk.
• Retains the snapshot virtual disk or consistency group snapshot virtual disk’s associated repository (if the virtual disk is designated as read-write).
• Retains any host mapping and access (any read-write requests will fail).
• Removes the snapshot virtual disk or consistency group snapshot virtual disk’s association with the current snapshot image.
• For a consistency group snapshot virtual disk, disables each member’s snapshot virtual disk.
NOTE: If you are finished with the snapshot virtual disk or consistency group snapshot virtual disk and do not intend to re-create it at a later time, you must delete the virtual disk, instead of disabling it.
1. From the AMW, select the Storage & Copy Services tab.
2. Select the snapshot virtual disk or consistency group snapshot virtual disk that you want to disable
• Copy Services → Snapshot Virtual disk → Disable. The Confirm Disable Snapshot Virtual Disk
window is displayed.
• Copy Services → Consistency Group Snapshot Virtual Disk → Disable. The Confirm Disable Consistency Group Snapshot Virtual Disk window is displayed.
3. Type yes in the text box and then click Disable to disable the snapshot virtual disk.
The snapshot virtual disk or consistency group snapshot virtual disk is displayed in the Logical pane with the Disabled Snapshot status icon. If you disabled a read-write snapshot virtual disk or consistency group snapshot virtual disk, its associated snapshot repository virtual disk does not change status. The write activity to the snapshot repository virtual disk stops until the snapshot virtual disk or consistency group snapshot virtual disk is re-created.
Re-creating A Snapshot Virtual Disk Or Consistency Group Snapshot Virtual
Disk
Use the Re-Create option when you want to re-create a snapshot virtual disk or consistency group
snapshot virtual disk that you previously disabled. Re-creating a snapshot virtual disk or consistency group snapshot virtual disk takes less time than creating a new one.
If you have a snapshot virtual disk or consistency group snapshot virtual disk that you no longer need, you can reuse it (and any associated snapshot repository virtual disk), instead of deleting it, to create a different snapshot virtual disk or consistency group snapshot virtual disk of the same base virtual disk. You can re-associate the snapshot virtual disk or consistency group snapshot virtual disk with the same snapshot image or a different snapshot image as long as the snapshot image is in the same base virtual disk.
NOTE: If the snapshot virtual disk or consistency group snapshot virtual disk is part of an online
copy relationship, you cannot perform the Re-create option on the virtual disk.
Keep these important guidelines in mind when you re-create a snapshot virtual disk or consistency group virtual disk:
• The snapshot virtual disk or consistency group snapshot virtual disk must be in either an Optimal
status or Disabled status.
• For consistency group snapshot virtual disk, all member snapshot virtual disks must be in a Disabled state before you can re-create the consistency group snapshot virtual disk.
• You cannot re-create an individual member snapshot virtual disk, you can re-create only the overall consistency group snapshot virtual disk.
• All write data on any associated snapshot repository virtual disk is deleted. Snapshot virtual disk or consistency group snapshot virtual disk parameters remain the same as the previously disabled virtual disk parameters. The original names for the snapshot virtual disk or consistency group snapshot virtual disk are retained. You can change these names after the re-create option completes.
To re-create a snapshot virtual disk or consistency group snapshot virtual disk:
1. From the AMW, select the Storage & Copy Services tab.
2. Select the snapshot virtual disk or consistency group snapshot virtual disk that you want to disable
and then select one of the following:
• Copy Services → Snapshot Virtual disk → Re-create. The Confirm Re-Create Snapshot Virtual Disk window is displayed.
• Copy Services → Consistency Group Snapshot Virtual Disk → Re-create. The Confirm Re- Create Consistency Group Snapshot Virtual Disk window is displayed.
3. Select whether to re-create the snapshot virtual disk or consistency group snapshot virtual disk using
an existing snapshot image, or a new snapshot image and then click Re-create.
The status of the snapshot virtual disk or consistency group snapshot virtual disk is changed from