The original post: /r/datahoarder by /u/stuartlevy67 on 2024-07-23 20:11:19.
Hardware: LSI9305-16e HBA, a couple of 8-bay 2010-era external SATA/SAS enclosures, some ST6000NM0105 SAS drives.
Puzzle (+ explanation below): why weren't any of the drives detected?
One of the new 6TB SAS drives worked fine in another RAID array, so the drives seemed OK.
The same controller+cables+enclosure works fine with an assortment of older Seagate drives -- ST4000NM0085 (4Kn SATA) and ST3000NM0023 (512n SAS).
The intent was to replace a similar older setup using a RocketRaid 2744, which is no longer supported under Linux.
Some frantic searching turned up comments about a new (2017?) SAS feature, Power Disable. It redefines pin 3 of the power connector. If that pin is powered, the drive shuts itself off. Looking closely at the spec sheet for the ST6000NM0105 shows it has this feature.
(The Seagate ST000NM0023 was too old to have Power Disable - that's why it worked!)
One page about this feature ( https://serverpartdeals.com/blogs/news/what-are-power-disable-hard-drives ) suggests a little strip of kapton tape covering that pin on the drive side. I tested with a bit of easily-removable scotch tape. It's surprisingly hard to make a thin strip of tape and put it in the right spot - but, it did work. The scotch-taped drive spun up and behaved normally in the enclosure that hadn't recognized it before.
I don't want to use kapton tape for drives that I still might return - its adhesive is really strong, so I might not be able to remove it.
Checked out the enclosure's backplane - could I modify it instead? Did the power supply have a 3.3V lead that I could just cut? Answer: for my enclosure, no. It appears to generate 3.3V on the backplane PCB. Oh well. I am not going to cut traces on the backplane.
Hope this saves someone else some trouble. Check whether your enclosure provides power on SAS/SATA pin 3, and check the detailed spec sheet for the drive(s) to see whether it implements power disable.