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Re: Re: [linux-lvm] vgscan not returning UPDATE



On Fri, Sep 20, 2002 at 05:50:08PM -0400, Ali Zaidi wrote:
> I seem to have LVM working for me now.
> This is just so some of you guys can tell me if i have done something horribly 
> wrong.
> As vgscan was never returning, i did a strace on it and found out that it was 
> getting stuck at a read call for /dev/nb0.
> 
> As i would only be using /dev/hd devices for LVM, i figured if i can comment 
> out references to "nb" from the LVM source, that might do the trick.
> I ended up commenting out two lines from tools/lib/lvm_dir_cache.c and one line 
> from tools/lib/lvm_check_partitioned_dev.c.
> After recompiling, vgscan now returns and i was also able to run pvcreate and 
> vgcreate successfully.
> 
> As i understand, if i am not going to be using Network Block devices under LVM, 
> i should be fine with the above arrangement.

Ali,

you shouldn't be forced to change the source.
If you don't need nbd anyways, disabling it in you kernel config should be fine.

FYI: LVM2 enables you to filter out devices in a config file.
     If you get a chance, please give it a try.

Regards,
Heinz    -- The LVM Guy --

> 
> Ali
> 
> 
> 
> ---- On Thu, 19 Sep 2002, James Hawtin (oolon ankh org) wrote:
> 
> > 
> > 
> > On Thu, 19 Sep 2002, Ali Zaidi wrote:
> > 
> > > Hi:
> > > I am a novice with LVM but after going through the man pages and howtos i 
> was
> > > unable to find a solution to my problem. I am hoping one of you might find 
> some
> > > time to point me in the right direction.
> > >
> > > I am trying to setup LVM on a RH box. I run vgscan before i can create the
> > > volumes but it never returns. Same thing happens with lvmdiskscan and 
> pvscan.
> > > Here is a -v and -d output of vgscan
> > 
> > Ok and now to try to answer your problem....
> > 
> > Did you do a pvcreate?
> > 
> > did the disk have existing data on it?
> > 
> > Try dd to write /dev/zero to the first bit of the partitions you want to
> > put into lvm. then do you vgscan which should then return with an error
> > saying it found nothing.... you can then use pvcreate on them
> > 
> > Of course your LAME disk layout could be confusing lvm in which case as a
> > work arround just have one lvm partion and use lvm to allocate the disk,
> > which is what you should be doing in the first place!
> > 
> > 
> > ------
> > 
> > And now a few quick questions and answers....
> > 
> > Q: I can allocate my disk better than LVM!
> > 
> > A: No you cannot! or rather you can allocate your disk when you
> > first get the machine to produce nice continuous partions. YOU CAN DO THIS
> > WITH LVM. If you have a brand new volume group and just add partions to
> > it they will be continuous with LVM as well.... Don't trust LVM.. you can
> > do a pvdisplay to show you this fact!
> > 
> > A2: Sure, but what happens if you want to remove 2 partions, that are not
> > next door to each other, and them make the one big partion... with fdisk
> > its a dd nigtmare... with LVM its easy.
> > 
> > Q: but how can I move my stuff onto another disk... I use DD!
> > 
> > A: SO? There is nothing special about lvm devices apart from the fact they
> > make things easer for you... You want to work that way, make your new
> > device using LVM or fdisk and do your dd! But you could save yourself time
> > by using pvmove!
> > 
> > Q: LVM adds a level of indirection to my disk.. surely its better to use
> > the real disk
> > A: Theoritically yes... but the translation to where on the disk is a
> > calculation done on your computer not on the disk the slowest part of the
> > operation is pulling stuff from your disk! Think about is a software raid
> > faster or slower? Its faster cos the slow part was the disk and now there
> > is more than one disk!
> > 
> > Q: I like to micromanage my disk...
> > A: You can do that with LVM if you like or you can let LVM do the best it
> > can for you and use your bonus time to go down the pub.
> > 
> > 
> > James
> > 
> > 
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm sistina com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> > 
> > 
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm sistina com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen Sistina com                           +49 2626 141200
                                                       FAX 924446
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