Planning for EMC PowerMax storage

Before using PowerMax storage

Support requirements

• For NPIV connectivity using EMC PowerPath installed on the virtual machine, the following apply:
  • PowerVC can capture and deploy AIX® 6.1 or 7.x virtual machines with EMC PowerPath enabled for the boot disks. PowerPath driver version 5.7 SP2 is required.
  • For AIX 7.1 virtual machines that use EMC PowerPath, deploys must use compute templates that specify at least 2 GB of memory.
• IBM® i virtual machines are not supported for NPIV connectivity.
• For vSCSI attachments, the supported multipathing software driver solutions are AIX path control module (PCM) and EMC PowerPath.
• Migration is supported only between Virtual I/O Servers that use the same multipathing software driver solution.
• PowerVC supports only secure communication to the Unisphere/REST server (HTTPS). You cannot register VMAX providers on HTTP-only ports.

Considerations for using PowerMax storage

• When attaching volumes out-of-band (outside of PowerVC) to a Virtual I/O Server where you are also using vSCSI connections to a virtual machine, volumes that are attached directly to the Virtual I/O Server must be on Fibre Channel ports that PowerVC is not using for vSCSI connectivity.

  For example, assume the Virtual I/O Server is getting its rootvg disk from a managed VMAX array. The rootvg volume should be masked by using Virtual I/O Server ports that are dedicated to this purpose, so that the VMAX driver in PowerVC does not mistakenly remove the mapping when a virtual machine volume is detached.

  The Fibre Channel ports that are dedicated for Virtual I/O Server vSCSI use outside of PowerVC must have Connectivity set to NPIV or NONE on the Fibre Channel Port Configuration in PowerVC.
• The VMAX driver lets you provision volumes to oversubscribed pools. The amount of oversubscription allowed is limited by the pool configuration on the VMAX. It is not limited by the Cinder max_over_subscription_ratio configuration option because PowerVC does not support pool scheduling where the option is used. The Available Capacity reported by the VMAX provider is the raw capacity available. It is not the unsubscribed capacity that would be left if the thin volumes were fully utilizing their allocated sizes.
• Port group considerations

  Port groups are named groupings of storage ports defined on the array.

  • Multiple PowerVC instances cannot manage the same storage and hosts if they have different storage port group configurations.
  • If the port group configuration is changed for the provider after deploying to a host with a vSCSI attached volume, subsequent volume attachments use the port group that is chosen for the initial deployment, whether it was for the same virtual machine or for a different virtual machine that uses the same VIOS. If that port group is not valid, an error is logged and the operation attempts to continue. If the port group does not have valid storage ports with connectivity to the virtual machine, then the deploy, attach, migrate, or remote restart operation fails.
  • For every attach operation, a VMAX port group is chosen in order to load balance between sets of front-end VMAX ports. See the information about port groups in Table 1. You might have multiple port groups if a significant number of VMAX front-end ports are cabled to your Fibre Channel fabrics.
  • You can choose to select a list of port groups on the storage template. When a virtual machine is deployed using this storage template, the port group with least number of masking views will be used to form the masking view. This only applies to the first volume of a specific connectivity type (NPIV, vSCSI) being attached to a virtual server (NPIV) or VIOS (vSCSI) as subsequent volumes will get assigned to existing masking views.
  • Port group configuration

    The term port group configuration refers to the list of port groups associated with a registered VMAX provider. This is the list of port groups that the storage provider can choose from when mapping a volume to a virtual machine.

    • A port group configuration is global for a storage provider.
    • For new registrations, the auto-configuration property is set to true. However, it has no effect if no fabrics are registered. When this property is true, each time the provider service restarts, including when fabrics are managed or unmanged, PowerVC evaluates the port groups defined on the array and filters out any that do not contain any ports that are visible on a registered fabric.
    • For VMAX providers that were registered in a PowerVC version prior to 1.4.1, the initial port group configuration consists of all possible storage port groups that were defined on the backend array at the time of registration. The auto-configuration property is not set to true. Therefore, port groups that might be invalid for host connectivity are not removed from the list.
    • You can manually enable or disable the auto-configuration property for any VMAX provider by running powervc-config storage portgroup --arrayid <vmax_serial> --auto-config true or false --restart.
    • To manually restrict PowerVC from using certain port groups or to add port groups to PowerVC, use the powervc-config storage portgroup command. Most of the command's options either require auto-config to be false, or the command automatically sets auto-config to false so that your port group configuration changes are not overwritten at the next service restart.

      For detailed instructions to use this command, run powervc-config storage portgroup --help.

    Note: A front-end Director port on the VMAX can be a member of multiple port groups.
• Volume considerations
  • The VMAX volume driver supports volume replication from the registered provider array to a target failover array. The SRDF replication group and other required resources must be configured outside of PowerVC. To enable a VMAX storage provider to use the SRDF group, run the powervc-config storage replication command. For instructions to use this command, run powervc-config storage replication -h.

    If you enable SRDF replication support and later disable the support, you might not be allowed to perform storage operations on the volumes that were created with a replication-enabled storage template while replication was enabled.

    For more information about the Dell EMC support, see the Volume replication support section on the page Dell EMC VMAX iSCSI and FC drivers page. You can also refer to the VMAX3 Volume Replication blog.

  • Only a single SRP (Storage Resource Pool) is supported on VMAX/PowerMax by the EMC driver. This is the pool selected when initially managing the VMAX/PowerMax array.
  • VMAX volumes have device IDs that are unique hexadecimal strings, such as 0B9A2. This value is listed on the PowerVC volume details page as the Storage provider volume name ID. When you choose to manage existing volumes from a VMAX provider, the volume names might be prefixed by this device ID. For example, 0B9A2+My Volume Name. This correlation is helpful for storage administrators.
  • When creating a new volume on a VMAX storage provider, the block device driver supports only the following characters in the name:

    0-9 A-Z a-z (space) ! # , - . @ _

    The PowerVC user interface and APIs accept other characters in volume names, including double-byte characters. However, any characters not in the above list are changed to underscores for the storage provider volume name.

• Deployed or captured volume considerations

  If you use a dot (.) in the first 14 characters of the display name of a virtual machine, the information before the dot must be unique to guarantee successful deployment.

• Storage template setting considerations
  • Service Level: The service level on the VMAX defines quality of service metrics for the workload, such as response time performance targets. See the VMAX white paper EMC VMAX3 FAMILY NEW FEATURES OVERVIEW for details. The default is None. If you specify a Service Level other than None, then there might be additional considerations. Service levels are more influential on older hybrid array types that have a combination of flash and spinning disk.
  • Workload: Not every service level and Workload combination is supported for every PowerMax array. It depends on configuration and licensing. There are additional considerations depending on your microcode level. For example, microcode 5978 does not support Workload levels like 5977 did, so if you have that level or later, choose None for Workload.

Converting legacy masking views and storage groups

python /usr/lib/python2.7/site-packages/powervc_cinder/cmd/samples/vmax_util.py -s 000196800573 migrate-cascaded -h

This migration can happen when the virtual machine is in Active state.

-h

Show the help.

-i VM_ID [VM_ID --vms VM_ID [VM_ID ...]

IDs of one or more virtual servers to migrate. This option cannot be used with -l.

-l

Output the list of virtual servers that have legacy storage groups in their masking views. This option cannot be used with -i.

-f

Continue with the operation even if a validation failure is encountered.

Example usage:

python /usr/lib/python3.6/site-packages/powervc_cinder/cmd/samples/vmax_util.py -s 000196800573 migrate-cascaded -l

python /usr/lib/python3.6/site-packages/powervc_cinder/cmd/samples/vmax_util.py -s 000196800573 migrate-cascaded -i 7b4b608b-aea3-4a4b-a878-ab9d73e6e781