Adding large disks to the system leads to messages "Very big device. Trying to use READ CAPACITY(16)."

This document (7023343) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 15

Situation

After a large disk has been added to the system the kernel logs a message like:

kernel: [93442.940949] sd 0:0:2:0: [sdc] Very big device. Trying to use READ CAPACITY(16).

p, li { white-space: pre-wrap; }

Resolution

While probing the new disk the size of it is calculated.If the size exceeds or is equal to 4294967296 sectors the message will be logged.

If the size of the disk is reduced by 1 sector so the entire disk size is max. 4294967295 sectors large the notice can be avoided.

This message is nothing to worry about unless additional messages indicating that the "Read Capacity (16)" has failed are logged.

Cause

Some internal kernel variables of the SCSI driver can hold maximum values of 4294967295 (0xffffffff). If a disk, larger than this amount of sectors is added to the system a function (read_capacity_16) needs to be called to deal with the larger amount of sectors. To do so special SCSI commands need to be sent to the disk.

Additional Information

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.