IBM Support

Compressed Volumes Are Limited to 96TiB

Flashes (Alerts)


Abstract

When creating a compressed volume, the size of the compressed volume should never be greater than 96TiB of user data. Any compressed volume that is larger than 96 TiB may experience a loss of access to the volume. A future release of software will prevent compressed volumes and compressed volume copies that are larger than 96TiB from being created.

This limitation applies to compressed volumes in regular pools only. Compressed volumes in data reduction pools are not affected.

This limitation does not affect data integrity.

Content

Any compressed volume that is larger than 96 TiB may experience a loss of access.
Most volumes that are greater than 96 TiB will not experience this loss of access. Nevertheless, IBM strongly recommends that customers stop using these volumes as soon as possible. If a volume experiences this issue, the volume may be taken offline, causing the application to lose access to the data. In some rare scenarios, some data may become unreadable.

Customers should not create any new compressed volumes that are larger than 96 TiB. A future release of software will not allow any compressed volumes or compressed volume copies to be created that are larger than 96 TiB


What to do if you have compressed volumes with a capacity of greater than 96 TiB

To retain the benefits of compression for this data, create multiple smaller compressed volumes and use host techniques to migrate the data from the current volume onto the new volumes.

Alternatively you can convert the large compressed volume into a thin provisioned volume by adding a thin provisioned copy to the volume and then deleting the compressed copy once the two copies are in sync.


How to check the capacity for your volumes

Using the GUI

In the volumes panel of the GUI, right click on the heading bar at the top of the table and add the Compressed column to the table

Then you can sort by the capacity column to find the largest volumes in the system, and check which of them have a compressed copy.

Using the CLI

The following command will list all compressed volume copies in your system
    lssevdiskcopy -filtervalue compressed_copy=yes -delim :

The output will look like this. The capacity, compressed_copy columns have been highlighted
    vdisk_id:vdisk_name:copy_id:mdisk_grp_id:mdisk_grp_name:capacity:used_capacity:real
    _capacity:free_capacity:overallocation:autoexpand:warning:grainsize:se_copy:compressed_copy
    :uncompressed_used_capacity
    0:vv1:0:0:ppp:16.00GB:2.00GB:2.01GB:6.00GB:796:off:20:32:no:yes:3.27GB
    1:se1:1:0:ppp:16.00GB:2.00GB:2.01GB:14.00GB:796:off:45:256:no:yes:4.46GB


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Document Information

Modified date:
22 June 2018

UID

ssg1S1005731