Hello, Владимир Дашевский wrote: >> Not all EMIs are one-shot events. Some can span seconds. Links don't >> always come up right after failures. Sometimes they require more than >> one hardresets to get back to working order. Link status report is >> not reliable. Sometimes they report offline for a while after certain >> events. If you know how to work around the above problems under a >> second, I'm all ears but I doubt it unless it involves an additional >> mechanical switch. >> > Well, for example, USB devices have a pull-up resistor on their D+ line. > DC bias can be used for detection of device presence without mechanical > switch. SATA is not USB and onlineness detection isn't that simple. Also, have you tried to run a system on a USB device over flaky connection? >> The echo to delete node is synchronous. It will return after the >> device is completely removed but please note that "removing" in this >> sense only covers the device itself. It will flush the request queue >> and spin the drive down but won't do anything about filesystems. You >> need to unmount first. hal and desktop stuff already do the right >> thing for devices marked removable. >> > Ok, but two more questions: > 1. Is there any generic mechanism of notifiing processes which had > previously opened device being deleted of this event? What will happen > to such processes? Is it possible to check who are those who uses the > drive at the moment? -EIO will happen, fuser, but if you want something intelligent, hal + dbus. > 2. If the drive was deleted is it possible to start it back without > physical re-connection? Can I simulate status change og that port to > force the driver to auto-detect block device? I don't really follow what you're trying to achieve but if you want some fancy snapshotting + remapping trick, the best place would be dm. > PS: as for this: >> I'll be happy to improve EH behavior but you need to come up with >> better reasons. >> > I can tell that for me enclosure management support is quite a good > reason. How is that in any way exclusive against longer detach delay? > Unfortunately, there is no this support in official kernel. I have > seen only limited support of activity LED in kernel 2.6.28. > However, I am using Debian where the latest kernel is only > 2.6.26. As a result I had to write a simple ahci_em module which > register simple proc interface to send LED states to all ICH9 > ports. However, final goal is to integrate this module with mdadm to > have proper indication of RAID state. The biggest obstacle is that there aren't too many enclosure devices floating around. What kind of device are you using? -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
