lvm doesn't document -m option

[Ketil Malde]

Binary package hint: lvm2

I'm currently looking into a mirrored disk setup for my server.

Now, I can do it the old-fashioned way using 'dm', but I notice there's also an option to do it with LVM, which seems a lot more flexible and ..well, nice.

Although 'lvcreate --help' shows '-m' as an option,it is not documented in the manual pages, and this makes me a bit queasy about using it. There also seems to be little information about it on the web.

So I think the manual page should either mention it, *or*, in the case it is unstable or otherwise not recommended, include a note to that effect.

[Ketil Malde (ketil-ii)]

I see from bug #119364 that this isn't enabled. I'll happily add my voice to the chorus requesting this, but in *any case* I think it should be documented.

[xomix (txomix)]

Just a "me too". I think it's very confusing having the wrong doc (old one) for lvm2. On top of that it is not easy to find info about the raid1 mirror setup through LVM instead of madm. I also find it more intuitive to mirror through LVM (like in other OSs, as AIX) than with mdadm.

I know this is definitely not the place to ask for info, but do you know if this raid1 mirror in LVM works OK? Is the dm-mirror module in the initramfs, ie, will my system boot if I place / and /boot under this type of mirror?

[Áron Sisak (asisak)]

Thanks for reporting this issue. What exactly do you mean by "is not documented"? I think the manual page for "pvcreate" is very straightforward in documenting the "-m, --mirrors" option.

[xomix (txomix)]

Well, first of all the mirror option is in lvcreate command, not the pvcreate command.
And the lvcreate man page installed in feisty doesn't say a word about the mirror (-m) flag. As stated in the bug report, lvcreate --help does show the option.
That's exactly what I mean by "not documented" option. ;)
Thanks for your answer.

[Áron Sisak (asisak)]

Sorry, I wanted to write the manual page of "lvcreate" (the "pvcreate" man page does not, of course). Which, however, documents the "-m / --mirrors" option properly in my opinion.

I mark this issue fixed, as we have a proper manual page in Gutsy. This bug, however does not seem appropriate to backport.

[Ketil Malde (ketil-ii)]

> I mark this issue fixed, as we have a proper manual page in Gutsy.

s/have/will have/ ?

I'm a bit surprised by this, as I presume I am not the only one who run a Ubuntu *release* on my production systems, and not a beta version. I realize this is not a security or otherwise crucial issue, but on the other hand, the fix (adding a few lines to the man page) should be harmless in the extreme.

And I notice we still don't have an answer as to what status LVM mirroring has in Edgy or Feisty, and whether it is stable enough to use instead of md mirroring...

-k