[smartmontools-support] Couple of questions about Offline data collection [resent in plaintext]

[l***@avc.su]

Hello.

My questions could be silly and answers could be obvious, but I'll be glad if you point me to the right docs.

What exactly does the Offline data collection? As far as I understood, it's contrary to short and long self-tests, and results are written to "Offline" attributes such as "Offline_uncorrectable".
Long self-test, above all, tries to read and verify every sector of the hard drive. This test can run for 214 minutes on my 2TB Seagate Barracuda 7200.14, but the Offline data collection runs only for 575 seconds.
Does it mean that Offline data collection is not trying to read/verify every sector, and there could be dozens of unreadable sectors out there, and I'll know about them only after long selftest?
I'm curious because we're relying on weekly "short" self-tests routines, and I'm wondering whether or not auto offline data collection could be combined with short selftests.

The other question is about Auto Offline data collection: I cannot enable it on my drives:

# smartctl -c /dev/sda
=== START OF READ SMART DATA SECTION ===
Offline data collection status:  (0x00) Offline data collection activity
                                        was never started.
                                        Auto Offline Data Collection: Disabled.
Self-test execution status:      (  0) The previous self-test routine completed
                                        without error or no self-test has ever
                                        been run.
Total time to complete Offline
data collection:                (  575) seconds.
Offline data collection
capabilities:                    (0x73) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        command.
                                        No Offline surface scan supported.
                                        Self-test supported.
                                        Conveyance Self-test supported.
                                        Selective Self-test supported.


# smartctl -s on -S on -o on /dev/sda
=== START OF ENABLE/DISABLE COMMANDS SECTION ===
SMART Enabled.
SMART Attribute Autosave Enabled.
SMART Automatic Offline Testing Enabled every four hours.

# smartctl -c /dev/sda                                                                                                                 
=== START OF READ SMART DATA SECTION ===
General SMART Values:
Offline data collection status:  (0x00) Offline data collection activity
                                        was never started.
                                        Auto Offline Data Collection: Disabled.

I've tried to issue the test with '-t offline', and I saw errors in '-l error' log, but the Auto collection cannot be enabled without any reasons.
The version is "smartctl 6.2 2013-07-26 r3841", kernel 3.10.0-514.6.1

Any hint is appreciated.

[Christian Franke]

Post by l***@avc.su
Hello.
My questions could be silly and answers could be obvious, but I'll be glad if you point me to the right docs.

See
https://www.smartmontools.org/wiki/Links#ATAATAPIReferences
https://www.smartmontools.org/wiki/Links#TheoriginalSMARTspecification

Post by l***@avc.su
What exactly does the Offline data collection? As far as I understood, it's contrary to short and long self-tests, and results are written to "Offline" attributes such as "Offline_uncorrectable".

This was possibly the original idea. What actually happens is hidden in
firmware and typically not documented by device vendors.

Post by l***@avc.su
Long self-test, above all, tries to read and verify every sector of the hard drive. This test can run for 214 minutes on my 2TB Seagate Barracuda 7200.14, but the Offline data collection runs only for 575 seconds.
Does it mean that Offline data collection is not trying to read/verify every sector, and there could be dozens of unreadable sectors out there, and I'll know about them only after long selftest?

Yes.

Post by l***@avc.su
...
# smartctl -s on -S on -o on /dev/sda
...
# smartctl -c /dev/sda
=== START OF READ SMART DATA SECTION ===
Offline data collection status: (0x00) Offline data collection activity
was never started.
Auto Offline Data Collection: Disabled.
I've tried to issue the test with '-t offline', and I saw errors in '-l error' log, but the Auto collection cannot be enabled without any reasons.

Then the "SMART ENABLE AUTOMATIC OFF-LINE" ATA command is unsupported by
the drive firmware (see -o option on smartctl man page).

Regards,
Christian