How to find the root partition with root=dhcp root-path=iscsi:::...
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount
/dev/disk/by-label/\x2f (LABEL=/)/dev/disk/by-label/ROOT (LABEL=ROOT)
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Quoted 8 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)
I think this was the intent of netroot=dhcp for remote block device protocols, then you can define something else in root=. Whether it is implemented yet I don't know.
Warren
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Quoted 7 lines · Warren Togami
Quoted 6 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount
Quoted 8 lines
Quoted 2 lines
/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)I think this was the intent of netroot=dhcp for remote block device protocols, then you can define something else in root=. Whether it is implemented yet I don't know.
Warren
Well, but the root-path does not specify the root partition!
Either we extend the iscsi:::: spec with a root partition or we make requirements like I did above. --
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Quoted 15 lines · Harald Hoyer
Quoted 14 lines · Warren Togami
Quoted 8 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)I think this was the intent of netroot=dhcp for remote block device protocols, then you can define something else in root=. Whether it is implemented yet I don't know.
Quoted 5 lines
Quoted 1 line
Warren
Well, but the root-path does not specify the root partition! Either we extend the iscsi:::: spec with a root partition or we make requirements like I did above.
root= cannot specify the root partition?
In any case, nothing really stops us from extending the iscsi RFC spec if we really want to.
Warren Togami
[email protected]
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Quoted 9 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)
BTW, I'm not against this as a fallback, but am I incorrect about root= being explicitly usable with netroot=dhcp?
Warren
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Quoted 15 lines · Harald Hoyer
Quoted 14 lines · Warren Togami
Quoted 8 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)I think this was the intent of netroot=dhcp for remote block device protocols, then you can define something else in root=. Whether it is implemented yet I don't know.
Quoted 5 lines
Quoted 1 line
Warren
Well, but the root-path does not specify the root partition! Either we extend the iscsi:::: spec with a root partition or we make requirements like I did above.
The RFC only says we need to boot off the LUN specified, 0 if none listed. That's your default partition.
It's workable, as these can be virtual disks anyways, but as Warren mentions, we can extend the RFC.
Also, you can specify root=LABEL=ROOT or root=/dev/sda1 etc and it should work, or at least it used to with the netroot= code. I haven't tested it this week -- vacation.
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Quoted 15 lines · David Dillow
Quoted 14 lines · Harald Hoyer
Quoted 13 lines · Warren Togami
Quoted 8 lines · Harald Hoyer
If we have root=dhcp and root-path from dhcp with "iscsi::... " nothing is know about the partition where root lives in.
RFC:
provide a pre-mount fallback, which tries to mount/dev/disk/by-label/\x2f (LABEL=/)
/dev/disk/by-label/ROOT(LABEL=ROOT)I think this was the intent of netroot=dhcp for remote block device protocols, then you can define something else in root=. Whether it is implemented yet I don't know.
Quoted 7 lines
Quoted 4 lines
Quoted 1 line
Warren
Well, but the root-path does not specify the root partition! Either we extend the iscsi:::: spec with a root partition or we make requirements like I did above.
The RFC only says we need to boot off the LUN specified, 0 if none listed. That's your default partition.
ok, so the LUN is the partition number?
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Quoted 5 lines · Harald Hoyer
Quoted 2 lines · David Dillow
The RFC only says we need to boot off the LUN specified, 0 if none listed. That's your default partition.
ok, so the LUN is the partition number?
No, a LUN is a whole disk. You would map the LUN to /dev/sda or /dev/sdb or such depending on which one it is, and use the entire disk -- no partitions needed. If you wanted to separate /var or /home etc, you would put them on a different LUN(s) -- partitions optional -- and use /etc/fstab to mount them.
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Quoted 11 lines · David Dillow
Quoted 4 lines · Harald Hoyer
Quoted 2 lines · David Dillow
The RFC only says we need to boot off the LUN specified, 0 if none listed. That's your default partition.
ok, so the LUN is the partition number?
No, a LUN is a whole disk. You would map the LUN to
/dev/sdaor/dev/sdbor such depending on which one it is, and use the entire disk -- no partitions needed. If you wanted to separate /var or /home etc, you would put them on a different LUN(s) -- partitions optional -- and use/etc/fstabto mount them.
hmm, so I would have to create a rule, which would look for the next disk which appears and has some /sys magic iSCSI attributes and try to mount the whole disk. --
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Quoted 7 lines · Harald Hoyer
Quoted 6 lines · David Dillow
Quoted 4 lines · Harald Hoyer
Quoted 2 lines · David Dillow
The RFC only says we need to boot off the LUN specified, 0 if none listed. That's your default partition.
ok, so the LUN is the partition number?
Quoted 8 lines
Quoted 5 lines
No, a LUN is a whole disk. You would map the LUN to
/dev/sdaor/dev/sdbor such depending on which one it is, and use the entire disk -- no partitions needed. If you wanted to separate /var or /home etc, you would put them on a different LUN(s) -- partitions optional -- and use/etc/fstabto mount them.hmm, so I would have to create a rule, which would look for the next disk which appears and has some /sys magic iSCSI attributes and try to mount the whole disk.
You're looking for the disk that makes the directory /sys/class/scsi_disk/<HOST>:0:0:<LUN>
HOST will almost always be 0, unless we try multiple iSCSI roots in sequence. LUN will be the one specified by root-path.
I'm not sure if you can match this via udev rules, perhaps using a match rule such as SYMLINK=="by-path/*-scsi-0:0:0:<LUN>"
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