Set up two thumb drives as one volume. (For Ray)
Find out where the drives are mounted using df I can see that the system software is on /dev/sda1
Looks like you already started doing a few things because I can see
pvscan PV /dev/sdb1 VG 128flash1 lvm2 [116.37 GiB / 0 free] PV /dev/sdd1 VG 128flash1 lvm2 [116.37 GiB / 760.00 MiB free] Total: 2 [232.74 GiB] / in use: 2 [232.74 GiB] / in no VG: 0 [0 ]
shows me that the 2 flash drives have already been put in the volume group "128flash1" and with
lvscan ACTIVE '/dev/128flash1/Two128GB_as_One' [232.00 GiB] inherit
I can see there is a logical volume called "Two128GB_as_One" and the logical volume is mounted at
/dev/mapper/128flash1-Two128GB_as_One on /media/256GB_as_One type ext4 (rw)
So I guess this section is "for Brian"! If there were nothing set up already
Recipe to set up two thumb drives as a single volume using LVM
1. Mark the drives are physical volumes to be used by LVM
pvcreate /dev/sdb1 pvcreate /dev/sdd1
2. Add the drives to a volume group, choose a name to identify the group (Ray used "128flash1")
vgcreate 128flash1 /dev/sdb1 /dev/sdd1
3. Create a logical volume; thats a lower case L in the option -l and 100%VG says "use all the space in the volume group"
lvcreate Two128GB_as_One -l100%VG 128flash1
4. Now you should be able to use it just like a single drive with
mkfs.ext4 /dev/128flash1/Two128GB_as_One mkdir /data mount /dev/128flash1/Two128GB_as_One /data
It looks like in your case the device mapper found it and put it at /media/Two128GB_as_One; that works too.
Add a drive to an existing logical volume
I have not done this yet and can't test right now... TEST IT YOURSELF seems like you should be able to add a drive to the volume group and then expand the file system to fill the larger drive?
Say you added /dev/sdg (and it is already partitioned), so make a new physical volume
then add it to the volume group
vgextend 128flash1 /dev/sdg1
then expand the logical volume (which no longer has a meaningful name!)
lvextend -l100%VG Two128GB_as_One
then resize the filesystem to fill the new space
Recipe to examine system
For example, you know LVM is in use but don't know how it's set up.
[email protected]:/mnt# pvscan PV /dev/md127 VG vg_mirror lvm2 [1.82 TiB / 0 free] Total: 1 [1.82 TiB] / in use: 1 [1.82 TiB] / in no VG: 0 [0 ] [email protected]:/mnt# vgscan Reading all physical volumes. This may take a while... Found volume group "vg_mirror" using metadata type lvm2 [email protected]:/mnt# lvscan ACTIVE '/dev/vg_mirror/lv_mirror' [1.82 TiB] inherit
mount /dev/vg_mirror/lv_mirror /mnt
Recipe to rename a volume group
I have two disks (one is a 'dd' copy of the other) and so they have identical volume names '/dev/magnia'. How do I change one?
Short answer: It is impossible. Using the UUID does not work!
Long answer: you have to have only one drive hooked up, boot from a rescue disk, and do it there. This sucks.
How do I shrink everything to fit on a smaller hard drive?
Figure out what space you want to make the partition before you start.
Preen: fsck /dev/magniatmp/root
Remove journal, turning the filesystem from ext3 to ext2
tune2fs -O ^has_journal /dev/magniatmp/root
e2fsck -f /dev/magniatmp/root
Resize the filesystem:
resize2fs /dev/magniatmp/root 10000M
Note the block count and size returned by resize command: 2560000 and 4k
There is also a swap space on this volume group, I can remove it for now and recreate it later.
Figure out the new size
bc 2560000*4 10240000
Resize the logical volume
lvresize -L 10240000 /dev/magniatmp/root
Create new journal to convert back to ext3:
tune2fs -j /dev/magniatmp/root
Shrink the physical volume
pvresize --setphysicalvolumesize 19G /dev/sdb5
Delete the partitions and re-create them smaller.