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the caching is on the drive. If the computer (initiator) requested the same block twice,
and it happened to be in the cache of the drive, then the drive would not have to read it
again from the disks, so in general, this number would be the same or always higher than
the Blocks sent to the Initiator. The higher the number goes, it means the less work the
heads on the disks have to do.
Number of Read or Write Commands who's size <= Segment Size:
The drive only
sends data to the computer in groups of blocks, into an area of the cache, called a cache
segment. If the commands being sent or the data being sent back is smaller or the same
size as a cache segment, it would register here. This number doesn't necessarily indicate
something good or bad – just a number of commands sent which were not the same size
or smaller than the cache segment – most are not.
Number of Read or Write Commands who's size > Segment Size:
This indicates data
or commands which had to be broken up into multiple transfers to send to the drive or
the computer. This doesn’t mean anything good or bad.
Vendor (Factory) Information:
This is a category heading for the next two lines.
Number of Hours Powered Up:
This indicates how long a drive has been powered up
(in hours), regardless of whether or not it was reading or writing – even just sitting idle
counts as being powered up. In fact, if the drive had power and was put to sleep, it would
also be counted here.
Number of Minutes until next SMART test:
The drive has two diagnostic tests. One is a
quick test, which only takes a few seconds, and is run by the drive itself (if not manually
triggered). The other is a full surface scan, which is only initiated by the user. In this ex-‐
ample, there is 1 minute until the drive is going to run the quick test on itself. The quick
test is how the drive updates this information.
The next section shows the Error Counter log. The output, when viewed with a fixed-‐
space font, forms a table – below is a sample of what that table might look like. The three
rows separate the data into reads (data accessed from the drives), writes (data written to
the drives), and verifies (data verified by reading/checking the data after a write).
Errors Corrected By ECC Fast/Delayed:
Counts the number of errors corrected by ECC
(Error Correction and Control).
Errors Corrected By Rereads/Rewrites:
Counts the number of errors corrected by re-‐
reading or rewriting the data on the drive.
Total Errors Corrected:
A sum of the first three columns.
Correction Algorithm Invocations:
Counts the number of times the total errors correct-‐
ed required correction algorithms.
Gigabytes Processed:
The total Gigabytes of data that passed through the Error Correc-‐
tion Algorithm.
Total Uncorrected Errors:
The number of errors that were never fixed by the system.
QOS 8-Bay User Manual
QOS Server is a subsidary of Ocean Tides Productions Ltd. © Copyright 2013
