Kit Gerrits wrote: > How do you expect them to know -in advance- that their disk will spin down, > possibly killing their filesystem? (Well, this has of course nothing to do with the sg_start utility.) > People are alresdy reporting these problems: > http://www.nslu2-linux.org/wiki/FAQ/DealWithAutoSpinDownOnSeagateFreeAgent > http://www.mail-archive.com/linux-usb-devel@xxxxxxxxxxxxxxxxxxxxx/msg52952.html The second report (about Seagate Freeagent USB, FireWire, eSATA with Linux 2.6.21-rc7) doesn't have enough detail. The former report (about Seagate Freeagent USB?) suggests a seemingly successful workaround for Seagate Freeagent disks: Switch on the allow_restart flag via sysfs. In Linux 2.6.24 and later, this flag is already enabled by default for all USB HDDs, i.e. the user doesn't have to do anything anymore to activate this fix. I guess the problem with /your/ disk could be that the kernel cannot easily tell from the type of error status which it gets from the firmware of the disk (of its USB chip, to be precise) that it should issue the START STOP UNIT command to get the disk going again. > I can understand Linux' UN*X roots imply big servers with SCSI disks that > need to be highly available. > It would, however, be nice if the O/S could optionally manage disks the way > 'a certain other O/S' does. > > If everyone could save those 10 watts per disk with their little server at > home, they might even save a few pennies. About auto-spin-down: Auto-spin-down (and thus auto-spin-up) managed by the kernel for SCSI disks (as opt-in feature; and thus for USB disks too) has been in the works, but I don't know what the status of this work is. About auto-spin-up: Note that many firmwares of cheap devices don't care a damn about standards; they just barely work with some luck with some versions of Windows if the Windows user doesn't do anything extraordinary with them. From what I understand, proper sense data from the disk would be enough for the kernel to send a START STOP UNIT to switch the motor on and to retry the last request. Somebody correct me if I'm wrong. BTW, if you stopped the disk with sg_start --stop, can you always successfully start it again with sg_start --start (if you run it before any other accesses to this disk)? -- Stefan Richter -=====-==--- =-== -=-=- http://arcgraph.de/sr/ -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
