Cisco MDS 9000 Family SAN Volume Controller Configuration Guide - Managing Virtual Disks [Cisco MDS 9000 NX-OS and SAN-OS Software]

Table Of Contents

Managing Virtual Disks

Virtualization Policies

Striped

Sequential

Image

Licensing Requirements

Configuring VDisks

Managing Virtual Disks

A VDisk is a virtual representation of a LUN that is exposed by the cluster to the hosts in a SAN. Each VDisk is independently associated with a single I/O group.

This chapter includes the following sections:

•Virtualization Policies

•Licensing Requirements

•Configuring VDisks

Virtualization Policies

Virtualization is the process of creating a pool of storage that can be split into VDisks. VDisks are visible to the host systems that use them and provide a common way to manage SAN storage. VDisks in the Cisco MDS 9000 Family use one of three virtualization policies: striped, sequential, or image.

Striped

When a VDisk is created using a striped policy its extents are allocated from the specified ordered list of MDisks. The allocation algorithm starts with the first MDisk in the ordered list and attempts to allocate an extent to it and then moves on to the next disk.

MDisk in turn process allocation—if a specified MDisk has no free extents then it misses its turn and the turn passes to the next MDisk in the list. When the end of the list is reached the turn loops back to the first disk in the list. The disk allocation proceeds until all required extents are allocated.

A specific MDisk can appear more than once in the list. This causes two extents to be allocated from the disk on each pass of the list. This might be useful when striping across MDisks of different sizes.

Sequential

When a VDisk is created using a sequential policy its extents are allocated from a single specified MDisk. The target MDisk is searched for regions containing free extents which are sequential such that the region is large enough to allocate the VDisk from completely sequential extents. If it finds more than once such region, it chooses the smallest region which satisfies this condition. If it finds no such regions, the VDisk creation fails.

Image

Image mode provides support to import existing data from a disk that was previously not managed by SVC.

Licensing Requirements

The total virtualized capacity that is licensed is the number of Gigabytes (GB) of VDisk capacity that are exported by the cluster. By default, this capacity is set to zero (0). The required amount of virtualization capacity must be licensed and configured using the feature enable command before creating any VDisk.

When you reach 90% capacity, any attempt to create or extend VDisks results in a warning messages. The software does not stop you from creating and expanding VDisks. Instead, errors are placed in the featurization log when your usage reaches or exceeds 100%.

Configuring VDisks

To configure VDisks, follow these steps.

Step 1 Create and identify three (3) VDisks from the marketing MDisk group and one (1) VDisk for the finance group.
switch1(svc)# cluster config SampleCluster
switch1(svc-cluster)# vdisk add crm-log iogroup 1 mdisk-grp marketing capacity 2 gb 
Warning: licensed virtualisation capacity has been exceeded
Tip The official purchased virtualization capacity must be configured before any VDisk is created.

This warning is used if you are exceed the amount of virtualization for which you have a license. Use the feature enable capacity command to configure the amount of purchased virtualization capacity.

Step 2 Configure the licensed virtualization capacity to be 200GB and continue to create the VDisks for the marketing and finance MDisk groups.
switch(svc-cluster)# vdisk add crm-data iogroup 1 mdisk-grp marketing capacity 2 gb clean 
switch(svc-cluster)# vdisk add crm-idx iogroup 1 mdisk-grp marketing capacity 1 gb
switch(svc-cluster)# vdisk add fn-1 iogroup 2 mdisk-grp finance capacity 2 gb 
Note The clean option initializes the entire VDisk to 0. Until the cleaning is done, the VDisk stays in the offline state.

Step 3 Exit to the SVC configuration mode.
switch(svc-cluster)# exit
switch(svc)#
Step 4 Verify the VDisk configuration using the show cluster cluster-name vdisk command.
switch(svc)# show cluster SampleCluster vdisk
-------------------------------------------------------------------------------
name             capacity     iogroup mdisk-grp name    policy      status
-------------------------------------------------------------------------------
crm-idx          1.00 GB      1       marketing         striped     online
crm-log          1.00 GB      1       marketing         striped     online
crm-data         2.00 GB      1       marketing         striped     offline
fn-1             2.00 GB      2       finance           striped     online
Tip The crm-data VDisk is offline due to the use of the clean option during the VDisk creation process in Step 2. Clearing a disk takes time—please wait for this process to complete.

Step 5 Reissue the show cluster cluster-name vdisk command to ensure that all VDisks are online.
switch(svc)# show cluster SampleCluster vdisk
-------------------------------------------------------------------------------
name             capacity     iogroup mdisk-grp name    policy      status
-------------------------------------------------------------------------------
crm-idx          1.00 GB      1       marketing         striped     online
crm-log          1.00 GB      1       marketing         striped     online
crm-data         2.00 GB      1       marketing         striped     online
fn-1             2.00 GB      2       finance           striped     online
Note The online status for each VDisk indicates that formatting is complete.

Step 6 Use the show cluster cluster-name mdisk-group command to verify the number of VDisks created in each MDisk.
switch(svc)# show cluster SampleCluster mdisk-grp 
-------------------------------------------------------------------------------
name             Capacity      free     extent   number    number    status
                                        size(MB) of mdisks of vdisks
-------------------------------------------------------------------------------
finance          7.56 GB       5.56 GB  16       5         1         online
marketing        6.48 GB       2.48 GB  16       5         3         online
Step 7 Use the show cluster cluster-name iogroup command to verify the number of VDisks available for each I/O group.
switch(svc)# show cluster SampleCluster iogroup 
------------------------------------------
ID  Name             Node count Vdisk count
------------------------------------------
1   io_grp0          2          3         
2   io_grp1          2          1         
3   io_grp2          0          0         
4   io_grp3          0          0         
5   recovery_io_grp  0          0 
Note The recovery-io-group is an internal SVC I/O group created for cluster recovery processes.

	Cisco MDS 9000 Family SAN Volume Controller Configuration Guide
	Managing Virtual Disks
Cisco MDS 9000 Family SAN Volume Controller Configuration Guide New and Changed Information Full Book PDF Preface SVC Product Overview Getting Started Creating and Managing Clusters Managing Back-end Storage Managing Virtual Disks Configuring Hosts Configuring Copy Services Upgrading CSM Software Configuring SPAN on SVC Interfaces Configuring a Dual Fabric SAN Environment	Download this chapter Managing Virtual Disks Feedback Table Of Contents Managing Virtual Disks Virtualization Policies Striped Sequential Image Licensing Requirements Configuring VDisks Managing Virtual Disks A VDisk is a virtual representation of a LUN that is exposed by the cluster to the hosts in a SAN. Each VDisk is independently associated with a single I/O group. This chapter includes the following sections: •Virtualization Policies •Licensing Requirements •Configuring VDisks Virtualization Policies Virtualization is the process of creating a pool of storage that can be split into VDisks. VDisks are visible to the host systems that use them and provide a common way to manage SAN storage. VDisks in the Cisco MDS 9000 Family use one of three virtualization policies: striped, sequential, or image. Striped When a VDisk is created using a striped policy its extents are allocated from the specified ordered list of MDisks. The allocation algorithm starts with the first MDisk in the ordered list and attempts to allocate an extent to it and then moves on to the next disk. MDisk in turn process allocation—if a specified MDisk has no free extents then it misses its turn and the turn passes to the next MDisk in the list. When the end of the list is reached the turn loops back to the first disk in the list. The disk allocation proceeds until all required extents are allocated. A specific MDisk can appear more than once in the list. This causes two extents to be allocated from the disk on each pass of the list. This might be useful when striping across MDisks of different sizes. Sequential When a VDisk is created using a sequential policy its extents are allocated from a single specified MDisk. The target MDisk is searched for regions containing free extents which are sequential such that the region is large enough to allocate the VDisk from completely sequential extents. If it finds more than once such region, it chooses the smallest region which satisfies this condition. If it finds no such regions, the VDisk creation fails. Image Image mode provides support to import existing data from a disk that was previously not managed by SVC. Licensing Requirements The total virtualized capacity that is licensed is the number of Gigabytes (GB) of VDisk capacity that are exported by the cluster. By default, this capacity is set to zero (0). The required amount of virtualization capacity must be licensed and configured using the feature enable command before creating any VDisk. When you reach 90% capacity, any attempt to create or extend VDisks results in a warning messages. The software does not stop you from creating and expanding VDisks. Instead, errors are placed in the featurization log when your usage reaches or exceeds 100%. Configuring VDisks To configure VDisks, follow these steps. Step 1 Create and identify three (3) VDisks from the marketing MDisk group and one (1) VDisk for the finance group. switch1(svc)# cluster config SampleCluster switch1(svc-cluster)# vdisk add crm-log iogroup 1 mdisk-grp marketing capacity 2 gb Warning: licensed virtualisation capacity has been exceeded Tip The official purchased virtualization capacity must be configured before any VDisk is created. This warning is used if you are exceed the amount of virtualization for which you have a license. Use the feature enable capacity command to configure the amount of purchased virtualization capacity. Step 2 Configure the licensed virtualization capacity to be 200GB and continue to create the VDisks for the marketing and finance MDisk groups. switch(svc-cluster)# vdisk add crm-data iogroup 1 mdisk-grp marketing capacity 2 gb clean switch(svc-cluster)# vdisk add crm-idx iogroup 1 mdisk-grp marketing capacity 1 gb switch(svc-cluster)# vdisk add fn-1 iogroup 2 mdisk-grp finance capacity 2 gb Note The clean option initializes the entire VDisk to 0. Until the cleaning is done, the VDisk stays in the offline state. Step 3 Exit to the SVC configuration mode. switch(svc-cluster)# exit switch(svc)# Step 4 Verify the VDisk configuration using the show cluster cluster-name vdisk command. switch(svc)# show cluster SampleCluster vdisk ------------------------------------------------------------------------------- name capacity iogroup mdisk-grp name policy status ------------------------------------------------------------------------------- crm-idx 1.00 GB 1 marketing striped online crm-log 1.00 GB 1 marketing striped online crm-data 2.00 GB 1 marketing striped offline fn-1 2.00 GB 2 finance striped online Tip The crm-data VDisk is offline due to the use of the clean option during the VDisk creation process in Step 2. Clearing a disk takes time—please wait for this process to complete. Step 5 Reissue the show cluster cluster-name vdisk command to ensure that all VDisks are online. switch(svc)# show cluster SampleCluster vdisk ------------------------------------------------------------------------------- name capacity iogroup mdisk-grp name policy status ------------------------------------------------------------------------------- crm-idx 1.00 GB 1 marketing striped online crm-log 1.00 GB 1 marketing striped online crm-data 2.00 GB 1 marketing striped online fn-1 2.00 GB 2 finance striped online Note The online status for each VDisk indicates that formatting is complete. Step 6 Use the show cluster cluster-name mdisk-group command to verify the number of VDisks created in each MDisk. switch(svc)# show cluster SampleCluster mdisk-grp ------------------------------------------------------------------------------- name Capacity free extent number number status size(MB) of mdisks of vdisks ------------------------------------------------------------------------------- finance 7.56 GB 5.56 GB 16 5 1 online marketing 6.48 GB 2.48 GB 16 5 3 online Step 7 Use the show cluster cluster-name iogroup command to verify the number of VDisks available for each I/O group. switch(svc)# show cluster SampleCluster iogroup ------------------------------------------ ID Name Node count Vdisk count ------------------------------------------ 1 io_grp0 2 3 2 io_grp1 2 1 3 io_grp2 0 0 4 io_grp3 0 0 5 recovery_io_grp 0 0 Note The recovery-io-group is an internal SVC I/O group created for cluster recovery processes.
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