On 10/09/2018 23:39, Don NetBSD wrote:
All SES control requests are optional as some simple enclosures can only report basic status. So its a genuinely has to be optional rather than a mandatory bit of the standard everyone ignores. For power control the enclosure either has to have dedicated drive power control hardware or initiate the stop unit commands for itself which would have been challenging up until the SAS era. The enclosures I worked on did support SES drive power :).On 9/10/2018 11:33 AM, Mike Pumford wrote:On 10/09/2018 01:49, Don NetBSD wrote:I'm not concerned with automatically detecting insertion/removal; that's the job that the operator performs (above) -- along with the tagging of the media, etc.I've done a lot of work with SAS disk enclosures that support SES. They often have an SES command that can turn off the drive in a bay prior to removal (but support is optional).Aren't standards *wonderful*? What value to "optional" if folks can elect toNOT implement?? <frown>
Anything AHCI will detect the removal. Not sure where netbsd is on removing/adding disk devices now. Last time I tested it with SATA ahci was 7.1 and I couldn't force a freshly inserted disk to create a wd device but this could be down to lack of knowledge on my part. AHCI did report the drive link rate correctly when I plugged it in. drvctl looks like it ought to be able to do the removal insertion but I'd need help from someone on the lists to advise on how to make it work with disks ;).My read of the SATA spec indicated that hot plugging was part of the SATA standard (and, by extension, SAS). But, that support for it on HBA's was(ahem) "optional". In particular, support for cold presence detect (but, I'mrelying on the operator to perform that function as HE will be the person doing the plugging/unplugging!)
Linux does have hotplug disk support (at least with SAS HBAs). Haven't tried AHCI as all my AHCI systems are NetBSD. ;)But, some bright-eyed dweeb uttered "Why not use an old server and write something in Linux to do the job?!" -- because, to said dweeb, Linux is the panacea for all problems technical (ignorance must be a wonderful state of mind -- everything is "easy-peasy"!)
Mike