[rescue] Boot fails with data access error (Solaris 10 on SB2500 Red)

[Nemo Nusquam]

Greetings.

My SB2500 Red rebooted and failed with the following error:


| Rebooting with command: boot
| Boot device: disk:a File and args:
|     ERROR: /packages/deblocker: Last Trap: Data Access Error
|Short disk read

The system had been up for a few months before this (and a few years 
before then) running Solaris 10.

Advice and assistance on how to proceed gratefully and gladly accepted.

Thank you in advance.

Sincerely,
N.

Note: I posted the same query on comp.unix.solaris (but no reply yet).