G A L A X Y ® A U R O U R A L S C O N F I G U R A T I O N A N D S Y S T E M I N T E G R A T I O N G U I D E
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Section 3 Management
The next section shows the Error Counter log. The output, when viewed with a fixed-space
font, forms a table – here is a sample of what that table might look like:
Definition of log entries:
‘read’ row is showing numbers relating to reads.
‘write’ row shows numbers relating to writes. Most of the write row will always be 0, because
this particular drive does what are called blind writes (i.e. Isn't capable of detecting errors on
writes without a verify or read)
‘verify’ row shows numbers relating to verifies (which are writes followed by reads to check the
data).
The first two columns are errors corrected by ECC (Error Correction and Control). With ECC
extra bits are sent with the data which provide parity for the data. If the parity doesn't match
the data, it is corrected by the processor on the drive. The third column shows errors which
were corrected by rereads (Where the drive had to reread the sector to get the data), or
rewrites (Where the drive had to write the sector more than once, based on a verify failure).
The forth column shows the total numbers of errors corrected (i.e. The sum of the first three
columns). The fifth column shows how many times it had to call the error correction algorithms
(whether or not the errors were corrected) – kind of also like a sum of the first three columns.
The sixth column indicates how many Gigabytes have passed through the error-checking
algorithm. In this case, a little over 8.3TB was processed. Finally, the right column is number
of errors which could not be corrected either with ECC or with rereads/rewrites.
The final two lines are: GLTSD, which records multiple test results (it should be disabled), and
finally, the long (extended) self-test duration, which indicates the amount of time in seconds
and minutes that it took the last time it ran the long self-test. This is a good indicator of how
long futures tests would take to run. In the example, the test took about 63 minutes to run,
which is very good for a 1TB SAS drive.
The following is a sample output of the SMART command from a SAS data drive:
Error counter log:
Errors Corrected by Total Correction Gigabytes Total
ECC rereads/ errors algorithm processed uncorrected
fast | delayed rewrites corrected invocations [10^9 bytes] errors
read: 130744731 235 0 130744966 130744966 8302.908 0
write: 0 0 0 0 0 11336.165 0
verify: 5990726 0 0 5990726 5990726 0.000 0
