"sudo smartctl -l xselftest -dsat,12 /dev/rdsk/c7t5d0" errors with 

ATA_READ_LOG_EXT (addr=0x00:0x00, page=0, n=1) failed: 48-bit ATA commands require SAT ATA PASS-THROUGH (16)

Read GP Log Directory failed

SMART Extended Self-test Log (GP Log 0x07) not supported

There are some unusual aspect to this that I cannot explain: The commands "sudo smartctl --xall xselftest -dsat,12 /dev/rdsk/c7t5d0" and "sudo smartctl --xall xselftest -dsat,16 /dev/rdsk/c7t5d0" return very different outputs with the former saying they are not supported and the latter clearly stating extended self test logs are supported:

General Purpose Log Directory Version 1

Address    Access  R/W   Size  Description

0x00       GPL     R/O      1  Log Directory

0x01       GPL     R/O      1  Summary SMART error log

0x02       GPL     R/O     51  Comprehensive SMART error log

0x03       GPL     R/O     77  Ext. Comprehensive SMART error log

0x06       GPL     R/O      1  SMART self-test log

0x07       GPL     R/O      1  Extended self-test log

0x09       GPL     R/W      1  Selective self-test log

0x10       GPL     R/O      1  NCQ Command Error log

0x11       GPL     R/O      1  SATA Phy Event Counters

0xa0       GPL     VS    4096  Device vendor specific log

On 13 August 2014 21:26, Christian Franke <Christian.Franke@t-online.de> wrote:
Richard Flint wrote:
I have set up smartd and have scheduled a daily short self test and weekly long self test of an OCZ VERTEX PLUS SSD. I have an issue where the "lifetime(hours)" column in the selftest report appears incorrect (see below). Interestingly, querying the power on hours attribute shows the correct figure of 5555 hours.

Any advice on why the hours value is incorrect in the self test logs would be appreciated.

This is likely a firmware bug. Check the extended self-test log (-l xselftest). It may provide more reasonable values.