EMC VMAX – Setting Auto Meta Attributes

This post provides instructions and information around the Symmetrix Auto Meta feature. The Auto Meta feature is a configurable option during the Bin File configuration or the setting can be enabled and configured via Unisphere or using Solutions Enabler (symcli).

Auto-meta Symmetrix Settings
So what does each setting mean:

auto_meta: Parameter must be enabled to use the auto meta device functionality. Auto_meta can be enabled only if the other auto meta parameters min_auto_meta_size, auto_meta_config and auto_meta_member_size are set to valid values.
auto_ meta_config: this parameter must be set to either striped or concatenated.
auto_meta_member_size: This is the default meta member size used when the auto_meta feature is triggered. This value as specified in cylinders (CYL) and needs to be less than or equal to 262668 cylinders. The min_auto_meta_size cannot be set less than the auto_meta_member_size.
min_auto_meta_size: this value is set by the user. This is the largest volume size that can be created before the Auto_Meta feature comes into play. When a user attempts to create a volume or volumes larger than the min_auto_meta_size and with auto_meta set to enabled what will result is the creation of a meta device. Thus the min_auto_meta_size is the size threshold that will trigger an Auto_Meta volume creation and any devices larger will automatically be a meta device. min_auto_meta_size needs to be less than or equal to the maximum defined value of 262669 cylinders (240GB) – these figures are for Enginuity Version 5874 and above.

A common mistake that has been encountered while provisioning via UIM is when a meta is requested that is not an exact multiple of the meta member size. The result is that a larger volume than was requested gets created with a multiple of the meta member size. For eaxmple if you resuest a size of 2TB and the auto_meta_member_size is set at 240Gig then the result would be a meta device with a size of 2160Gig.

Example with Auto_Meta Disabled:
As you can see from the image below the Auto Meta details have not been completed during the BIN File configuration and the default is Auto Meta disabled:

The result of not having Auto_Meta configured is that we are unable to provision volumes larger than the defined Meta Size from a Thin Pool as is the case in this example:

Procedures For Setting Auto_Meta Attributes
Via Solutions Enabler:
1.Run the following command to verify if Auto_Meta is disabled: symcfg list -sid xxx -v
2.If Auto_Meta is not enabled, create a file auto_meta.txt with the following configuration:
set Symmetrix auto_meta=enable, min_auto_meta_size=262669, auto_meta_member_size=262668, auto_meta_config=striped;
3.Run the following command: symconfigure -sid xxx -f auto_meta.txt commit -nop

This configuration specifies that any attempt to create a volume larger than 262669 cylinders will exceed the minimum auto meta size threshold and will therefore trigger an Auto_Meta device creation.

Via Unisphere:
Go to the Unisphere For VMAX Interface
1. Select the Symmetrix system.
2. Select System > Settings > Symmetrix Attributes to open the Symmetrix Attributes page.
3. Select to enable “Enable Auto Meta”.
4. Set the following properties:
◆ Minimum Meta Capacity — Type the minimum volume size that will trigger the creation of a meta volume.
Setting a value of 262669 cylinders.
◆ Member Capacity — Type the size of the meta members to use when creating meta volumes.
Setting a value of 262668 cylinders.
◆ Configuration —meta configuration as Striped when creating meta volumes.
When enabled and attempting to create a volume larger than the value specified in the Minimum Meta Capacity field, or larger than 240 GB, it automatically triggers the creation of a meta volume according to the values specified in the Member Capacity and Configuration fields.

Now if we take a look in SymmWin we can see that Auto Meta is enabled and configured:

Now the creation of the volumes that had failed in the example above will succeed as a result of configuration changes made:

Note that it is possible using Symcli to manually configure meta volumes that ignore the Auto_Meta setting. Example creating a 4 way meta using volumes 100 – 103:
Creta TDEVs and BInd to Pool:
create dev count=4, size=5120MB, emulation=fba, config=TDEV;
bind tdev 0100:0103 to pool Pool_Name preallocate size=ALL;

Create Meta Device:
“form meta from dev 100 config=striped; add dev 101:103 to meta 100;”

Note: You can check the status using command symcfg list -v

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