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 ---- 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/
