How best to add SSD to LVM system and install new version?

[lindsayward]

Hi, and thanks in advance for replying!
I have an existing 12.04 system with 2 HDDs setup using LVM, and I want to know the best way to add my new SSD and install 14.04 on it (best in terms of performance and maintainability).

I think I would like to keep using LVM, but I'm not sure how best to combine/move or start over for the LVs, and what should be on the SSD and what should stay on the HDDs. I am thinking I could do a fresh install to the SSD and leave the existing install as is, until I get it right (safety), then somehow reclaim the space on the current HDDs... maybe.

I use the system for MythTV (run ubuntu rather than mythbuntu though), hence the large "movies" drive.
Here are some details of the current system...
I have connected the new SSD (called sdc) but not done anything to it yet.



fdisk -l
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
81 heads, 63 sectors/track, 765633 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0xbc04db52

Device Boot Start End Blocks Id System
/dev/sda1 2048 3907029167 1953513560 83 Linux

Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000d1e6b

Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 976895 487424 83 Linux
/dev/sdb2 976896 3907028991 1953026048 8e Linux LVM

Disk /dev/sdc: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg-lvroot: 20.0 GB, 19998441472 bytes
255 heads, 63 sectors/track, 2431 cylinders, total 39059456 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg-lvhome: 9999 MB, 9999220736 bytes
255 heads, 63 sectors/track, 1215 cylinders, total 19529728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg-lvswap: 4999 MB, 4999610368 bytes
255 heads, 63 sectors/track, 607 cylinders, total 9764864 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/vg-lvmovies: 3965.3 GB, 3965290807296 bytes
255 heads, 63 sectors/track, 482085 cylinders, total 7744708608 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

pvdisplay
--- Physical volume ---
PV Name /dev/sdb2
VG Name vg
PV Size 1.82 TiB / not usable 4.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 476812
Free PE 0
Allocated PE 476812
PV UUID XHeIXt-d3xr-Wo1f-rZF9-7rCm-nvey-AfJ0QU

--- Physical volume ---
PV Name /dev/sda1
VG Name vg
PV Size 1.82 TiB / not usable 4.09 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 476931
Free PE 0
Allocated PE 476931
PV UUID AYUyq4-1YYp-kOK2-FYyB-qRjV-nZKx-vie8lT

vgdisplay
--- Volume group ---
VG Name vg
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 26
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 2
Act PV 2
VG Size 3.64 TiB
PE Size 4.00 MiB
Total PE 953743
Alloc PE / Size 953743 / 3.64 TiB
Free PE / Size 0 / 0
VG UUID KoLIJC-xIB9-uKKh-Q7Ba-nfQR-Hf8I-OqsXS5

lvdisplay
--- Logical volume ---
LV Name /dev/vg/lvroot
VG Name vg
LV UUID iNv6Ss-DDbi-IFdG-dSmB-Ewee-Rxzc-AZvI8L
LV Write Access read/write
LV Status available
# open 1
LV Size 18.62 GiB
Current LE 4768
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0

--- Logical volume ---
LV Name /dev/vg/lvhome
VG Name vg
LV UUID rEKL7X-nsFk-qpu1-jAVG-ENzm-w1la-igpQRb
LV Write Access read/write
LV Status available
# open 1
LV Size 9.31 GiB
Current LE 2384
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:1

--- Logical volume ---
LV Name /dev/vg/lvswap
VG Name vg
LV UUID VfIbym-pFvq-Izkc-G0aa-9Yb4-3EXo-UwwPr4
LV Write Access read/write
LV Status available
# open 2
LV Size 4.66 GiB
Current LE 1192
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:2

--- Logical volume ---
LV Name /dev/vg/lvmovies
VG Name vg
LV UUID 6Xdubx-0I0S-2dWu-cvNz-2jlU-EUWy-dA7qbr
LV Write Access read/write
LV Status available
# open 1
LV Size 3.61 TiB
Current LE 945399
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:3

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg-lvroot 19G 6.1G 12G 35% /
udev 1.7G 4.0K 1.7G 1% /dev
tmpfs 690M 1016K 689M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 1.7G 108K 1.7G 1% /run/shm
/dev/sdb1 473M 53M 398M 12% /boot
/dev/mapper/vg-lvhome 9.3G 3.1G 5.8G 35% /home
/dev/mapper/vg-lvmovies 3.6T 1.8T 1.7T 51% /movies


Let me know if there is any other info that would be useful, and thank you for taking the time to help me out!

[oldfred]

I am not a fan of LVM, but in your case where you want one large movie partition, I guess it makes sense.
The main disadvantage I see is that if any drive fails you lose all data on both drives.

Advantages/Disadvantages LVM Post #9
http://ubuntuforums.org/showthread.php?t=1586328
https://wiki.ubuntu.com/Lvm

sudo apt-get install lvm2
sudo vgchange -ay
LVM gui tool:
http://www.howtogeek.com/127246/linux-sysadmin-how-to-manage-lvms-with-a-gui/
sudo apt-get install system-config-lvm

I would just use SSD as / & /home. Then entire LVM drives could be your movies and system would be very fast.
Another recent thread on SSD (only).
http://ubuntuforums.org/showthread.php?t=2227050

If Linux only I do prefer to use gpt partitioning, just because it also has a backup for reliability.
GPT Advantages (older but still valid) see post#2 by srs5694:
http://ubuntuforums.org/showthread.php?t=1457901
https://wiki.archlinux.org/index.php/GUID_Partition_Table#Advantages_of_GPT

Install 14.04 Something Else explanation and screenshots (note boot load to VM, most may install to MBR of drive sda, or sdb)
http://www.tecmint.com/ubuntu-14-04-installation-guide/

[lindsayward]

Thanks heaps for the reply.
I liked the idea of LVM, but I don't think it really helps much in my situation, and I had a nightmare experience trying to add a new disk (LVM problem after adding new disk (http://ubuntuforums.org/showthread.php?t=2225874)). So, I would be happy to start fresh WITHOUT LVM if that's simple enough to do.
MythTV allows me to specify multiple "storage groups" so I can spread my movies over new disks any time without much effort. This lets MythTV spread the load over multiple disks, but I'm actually unsure how LVM affects this, since MythTV sees it as one volume, I think. It might even be better with different volumes. Does anyone know?

Also, my SSD is 120GB and I don't need nearly that much space for / and /home (see df output above), but anyway...

So, what would be the best and safest way to reinstall without LVM and still be able to access the files that are in LVs at the moment?

[oldfred]

I can move thread to MythUbuntu or multimedia sub-forum where those with Myth may see thread.

You can just install Ubuntu to SSD and then add the software to mount & use existing LVM. No idea about Myth issues. When I install I see it uninstalling software I do not use & that includes RAID & LVM. I hate that it uninstalls gparted as that is one of the first things I reinstall. I have several drives so I can use gparted on all but my system drive.

[lindsayward]

Thanks. My main issues are not about MythTV, and I do not use Mythbuntu. I tried it first, but realised I had to keep installing standard software I wanted, so now I use normal/full ubuntu.
So: install ubuntu 14.04 to the SSD (perhaps using 20GB for / and 100GB for /home?)
Then install LVM2 and mount the existing LVs...
Then, how could I "get out of" LVM??

[oldfred]

I think the only way is to fully backup and then remove the LVM and repartition.

The format is so different there is no way to convert. It is logical partitions overlayed over the physical partitions.

[lindsayward]

Thanks. I think I'll install with / and /home on the SSD (not using LVM), then mount the existing LVM partitions...
Then copy the old LVM /home from the HDD into the new one, install programs and get my settings right, then try and reclaim the space used by the LVM partitions I won't keep using... and keep only the /movies.
Let's see how we go...