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Joined duela 2 urte
Cake day: urt. 22, 2021


A rather more sophisticated way to identify a disk, if it’s in an enclosure that has ID LEDs, is to use sg_ses.

The rough process for that is:

  • Run lsscsi -g to get the generic SCSI device (/dev/sgN) for the enclosure.
  • Run lsscsi -t to get the SAS address for a disk. (Not sure whether this will work if it’s a SATA enclosure; all of mine are SAS.)
  • Run sg_ses -p aes /dev/sgN | less, where /dev/sgN is the enclosure’s generic SCSI device. Look through the output to find the SAS address and, from that, get the index number of the disk.
  • Run sg_ses --set ident --index I /dev/sgN, where I is the disk index number and /dev/sgN is the enclosure’s device. This will turn on the ID LED for the disk.
  • Run sg_ses --clear ident --index I /dev/sgN to turn the LED off.

You can also use fault instead of ident to turn on the “drive fault” LED, in case the enclosure has those but not ID LEDs.

One super-easy way to identify disks on the fly is just to do a cat </dev/sdx >/dev/null and see which disk activity light stays on.

What I do is figure out which names in /dev/disk/by-path correspond to which disks. The by-path names are stable, even if you replace the disks (as long as the cabling doesn’t change). Then I set up aliases in /etc/zfs/vdev_id.conf to give the disks names that correspond to the external labels on the enclosure.

For example, disk /dev/disk/by-path/pci-0000:06:08.0-sas-0x5842b2b2167fc188-lun-0 might be the disk in slot zero in the array I’ve designated as “array0”. So /etc/zfs/vdev_id.conf would have:

alias  array0-0  pci-0000:06:08.0-sas-0x5842b2b2167fc188-lun-0

Then I create the pool with the /dev/disk/by-vdev names so I can tell immediately what each disk is. (If you’ve already created the pool, you can export it and then use zpool import -d /dev/disk/by-vdev to switch to the vdev names.)

In theory, you can use some other settings in /etc/zfs/vdev_id.conf to get the system to enumerate the disks itself, rather than working out the aliases by hand. In my case, my enclosures don’t have stable numbering that the automatic settings can work with.

Another good reason is the sheer quantity of bullshit you can read on Reddit. Most people talk, talk, and they really don’t know a shit of what they’re talking about.

That’s just a factor of the size of the site, though. If Lemmy gets big, even if it’s widely distributed, there’ll be large communities with tons of people, most of whom won’t know what they’re talking about.

Community-wise, you can do just fine on Reddit if you curate your subreddits carefully. (And I happen to think that Reddit’s interface is more conducive to useful discussion than many other places, like Facebook or web forums.)

IMHO, the biggest advantage of Lemmy over Reddit is the federation. I think Reddit gets a lot right, and those things plus federation might well make for my ideal link/discussion site.