On Tue, Dec 1, 2020 at 9:42 AM Patrick O'Callaghan <pocallag...@gmail.com> wrote: > > On Tue, 2020-12-01 at 09:01 -0700, Chris Murphy wrote: > > On Tue, Dec 1, 2020 at 6:59 AM Tom Horsley <horsley1...@gmail.com> wrote: > > > > > > On Tue, 1 Dec 2020 14:52:21 +0100 > > > Roberto Ragusa wrote: > > > > > > > How do you power them down? > > > > > > I don't know about the original poster, but my "noauto" disks > > > timeout and power down all by themselves, then even when they aren't > > > mounted at all, every time I reboot, the reboot hangs while it > > > spins up the disks for some reason. I constantly wish I could make > > > it stop doing that. > > > > Enumeration. I'm not sure if it's udev scanning everything, or the > > kernel or both. And also maybe libblkid, to know what everything is. > > The only way it can know what it is, it needs to be spun up to read > > the partition map and all the signatures on each partition. > > Obviously it needs to spin up if it needs to know these things. My > point is that it doesn't need to know them until I tell it.
Yeah that's not how it works. $ dmesg | grep sda [ 2.149354] sd 0:0:0:0: [sda] 3907029168 512-byte logical blocks: (2.00 TB/1.82 TiB) [ 2.149397] sd 0:0:0:0: [sda] 4096-byte physical blocks [ 2.149514] sd 0:0:0:0: [sda] Write Protect is off [ 2.149545] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.149722] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 2.235611] sda: sda1 [ 2.236610] sd 0:0:0:0: [sda] Attached SCSI disk $ The second to last line, where it discovers the sda1 partition, is needed in order to create all the symlinks for all the various parts of that drive. Not just the dev node, but also the /dev/disk/by- things. If you don't want that to happen, you'd need a udev rule to inhibit that. And then when it goes looking for a particular fs UUID in fstab to mount, of course it doesn't exist, so the mount will fail. It doesn't know it needs to scan everything NOW. There's no correlation between fs UUID in fstab to a particular device until it's scanned, which happens by udev during early startup. -- Chris Murphy _______________________________________________ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
