does sym53c8xx_2 hardware support hotplug
Hi,
Does the hardware sym53c8xx_2 works with support removing and adding devices?
When using sym53c8xx_2 if we find storage, remove the device using the sysfs/proc interface, then physically remove the device, everything goes well. However, if we physically plug the disk back in and try to readd it through the sysfs/proc scanning interfaces, it looks like scsi_scan.c's inquiry will time out. This causes the sym error handler to run, which works great and we end up doing a BUS RESET (BDR failed so we got escalated), and after that the inqiury is retried and we find the device and it works fine.
Is the inquiry timing out expected? Does the hardware even support hotplug? Or does it support it partially support it (support it with some help), and we are we supposed to be manually resetting the bus, with something like a sg_reset, after we have physically plug the disk back in?
Thanks for any info,
Mike
Hi Mike,
Quoted 4 lines · Mike Christie
Hi,
Does the hardware
sym53c8xx_2works with support removing and adding devices?
Oh. Hmm. That is tricky and complicated.
Quoted 2 lines
When using
sym53c8xx_2if we find storage, remove the device using the sysfs/proc interface, then physically remove the device, everything goes well. However, if we physically plug the disk back in and try to readd it through the sysfs/proc scanning interfaces, it looks like scsi_scan.c's inquiry will time out. This causes the sym error handler to run, which works great and we end up doing a BUS RESET (BDR failed so we got escalated), and after that the inqiury is retried and we find the device and it works fine.
Yes.
Quoted 2 lines
Is the inquiry timing out expected? Does the hardware even support hotplug? Or does it support it partially support it (support it with some help), and we are we supposed to be manually resetting the bus, with something like a
sg_reset, after we have physically plug the disk back in?
Hi, join the club.
As the saying goes: Radio Yerewan answers: in principle, yes.
The whole matter of SCSI parallel hotplugging depends strongly on the backplane. For fun reading have a look at
SPI-3 Annex D: Removal and insertion of SCSI devices.
It basically leaves it open to the vendor of the backplane how much intelligence he wants to put in there.
But yes, sending a SCSI reset is listed there. It actually states that the RST line should be asserted continuously by the initiator during the hotplugging process.
HTH.
Cheers,
Hannes
Signature · 8 lines
Dr. Hannes Reinecke zSeries & Storage [email protected] +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Markus Rex, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html