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fedora-users: Re: Fedora 15 + scsi tape drive

Re: Fedora 15 + scsi tape drive

From: Cameron Simpson <cs_at_nospam>
Date: Mon Oct 17 2011 - 04:22:47 GMT
To: Chris Adams <cmadams@hiwaay.net>, users@lists.fedoraproject.org

On 16Oct2011 20:15, Chris Adams <cmadams@hiwaay.net> wrote:
| Once upon a time, Cameron Simpson <cs@zip.com.au> said:
| > I'm all ok with providing sda/hda as discovered, _provided_ one also has
| > nice bus/id type names as well. Solaris' bus/id/partition drive names
| > looked long and complicated but they were reliable - you could look at
| > the device ids and know what the OS would call them.
|
| See /dev/disk/by-{id,path,uuid}.

And does this work _before_ boot, in the root= kernel command line, via
grub.conf?

| This is also an advantage of LVM; it
| knows how to find the physical volumes, and you generally don't have to
| care (/dev/vg_foo is always /dev/vg_foo). Even Solaris' bus number
| wasn't stable in the face of card changes IIRC.

Yeah, but that is at least infrequent.

With my problem system, the hardware RAID appears before the SATA boot
drives. If RAID volumes are missing (totally failed, for example - there's
some weak hardware involved here) then my boot drive can be any of sda, sdb
or sdc. Normally it is sdc because the RAID has two volumes which land at
sda and sdb.

| The problem with enumerating devices by HBA/bus/ID/LUN is that today's
| storage is more dynamic. USB ports are "SCSI" (protocol); how do you
| number those? IIRC USB ports on a hub are not deterministically
| ordered, so a flash card reader on a hub may come before a thumb drive
| on one boot and after on the next.

I would at least number then _last_! (I know this is slightly
simplistic.)

But I'd be happy if linux presented /dev/usb0/node2/part1, for example.
I don't _care_ about the protocol, and few users of the device _by_name_
care either. As far as that level of user is concerned it is a block
storage device; the protocol is the kernel's problem, not the user's.

Cheers,
-- Cameron Simpson <cs@zip.com.au> DoD#743 http://www.cskk.ezoshosting.com/cs/ One rider (Kenny Roberts?) described The CorkScrew as: It's like driving your bike into a phone booth, and then having the phone booth dropped down an elevator shaft! -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines