History of a Logical Volume named ARCHIVE

Sunday, January 17, 2010
This is the history of a storage location named "ARCHIVE" created today. I hope it will stay alive for few years in future.
This ARCHIVE partition is on a 320GB Samsung disk (HD321KJ) which nearly covers the whole disk. Only 1st 2GB is used as SWAP partition just in case a running Linux installation may need or a Live CD may use during boot.
I want to keep all backup on this partition and need to free up the other disks for OS installation which currently hold them.
I intended to give the whole disk for archiving, so a single partition in single PV would have sufficed. But I created 3 partitions of 100GB size and then added them in the volume group (VG). The rationale is if the hard disk started giving problem; such as inode corruption, physical damage, bad bocks, then usually that will affect particular sectors or blocks and not the whole disk. And I can move data of particular physical volume (PV) using "pvmove" to a smaller hard disk (e.g. 120GB) if needed. I hope this granularity will help me in future.
Also, I decided to go for ext4 as it is superior to ext3.
I have done all of the following using openSUSE 11.2 Live CD as it has the latest tools and good support for ext4 (default FS on openSUSE 11.2 is ext4). Though the partitions have been created on the running Debian Lenny installation I had but it does not ext4 partition creation yet. So, the rest is how I have done the things.

Disk Structure

# fdisk -l /dev/sdb
Disk /dev/sdb: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000931b4

   Device  Boot     Start         End      Blocks   Id  System
/dev/sdb1               1         261     2096451   82  Linux swap / Solaris
/dev/sdb2             262       13315   104856255   8e  Linux LVM
/dev/sdb3           13316       26369   104856255   8e  Linux LVM
/dev/sdb4           26370       38913   100759680   8e  Linux LVM

Create Physical Volumes (PV)

# pvcreate /dev/sdb2
# pvcreate /dev/sdb2
# pvcreate /dev/sdb2

Status of PV

# pvs
  PV         VG        Fmt  Attr PSize  PFree
  /dev/sdb2  vgarchive lvm2 a-   99.99G     0
  /dev/sdb3  vgarchive lvm2 a-   99.99G     0
  /dev/sdb4  vgarchive lvm2 a-   96.09G     0

# pvscan
  PV /dev/sdb2   VG vgarchive   lvm2 [99.99 GB / 0    free]
  PV /dev/sdb3   VG vgarchive   lvm2 [99.99 GB / 0    free]
  PV /dev/sdb4   VG vgarchive   lvm2 [96.09 GB / 0    free]
  Total: 3 [296.07 GB] / in use: 3 [296.07 GB] / in no VG: 0 [0   ]

# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sdb2
  VG Name               vgarchive
  PV Size               100.00 GB / not usable 6.69 MB
  Allocatable           yes (but full)
  PE Size (KByte)       8192
  Total PE              12799
  Free PE               0
  Allocated PE          12799
  PV UUID               3JQwlp-l00C-ws7g-F4OJ-0RPi-mwd1-vFhUyC
  --- Physical volume ---
  PV Name               /dev/sdb3
  VG Name               vgarchive
  PV Size               100.00 GB / not usable 6.69 MB
  Allocatable           yes (but full)
  PE Size (KByte)       8192
  Total PE              12799
  Free PE               0
  Allocated PE          12799
  PV UUID               Q4b9QY-RmEK-8QfJ-JPRs-vBhf-nLPs-8f3Aj5
  --- Physical volume ---
  PV Name               /dev/sdb4
  VG Name               vgarchive
  PV Size               96.09 GB / not usable 6.12 MB
  Allocatable           yes (but full)
  PE Size (KByte)       8192
  Total PE              12299
  Free PE               0
  Allocated PE          12299
  PV UUID               RWuFWt-1xtl-uJK5-RHKv-TojO-EaRD-xucbu6

Create Volume Group (VG)

vgcreate -s 8M vgarchive /dev/sdb2 /dev/sdb3 /dev/sdb4

Note: extent size of 8MB has been used instead of default 4MB because that leads to a maximum logical volume size of around 256GB. But I will be having a single logical volume of 296GB (see below).

Status of VG

# vgs
  VG        #PV #LV #SN Attr   VSize   VFree
  vgarchive   3   1   0 wz--n- 296.07G    0

# vgdisplay
  --- Volume group ---
  VG Name               vgarchive
  System ID             
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               296.07 GB
  PE Size               8.00 MB
  Total PE              37897
  Alloc PE / Size       37897 / 296.07 GB
  Free  PE / Size       0 / 0   
  VG UUID               fsZyxq-JAcA-NAPk-L1at-gzOb-UiXa-7ufVXE

Create Logical Volume (LV)

lvcreate -n lvarchive -l 37897 vgarchive

Note: Used all available extents.

Status of LV

# lvs
  LV        VG        Attr   LSize   Origin Snap%  Move Log Copy%  Convert
  lvarchive vgarchive -wi-ao 296.07G                                      

# lvscan
  ACTIVE            '/dev/vgarchive/lvarchive' [296.07 GB] inherit

# lvdisplay
  --- Logical volume ---
  LV Name                /dev/vgarchive/lvarchive
  VG Name                vgarchive
  LV UUID                sGk5MF-WF1h-okA0-OGhZ-i6Hy-AmTH-gvOW0R
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                296.07 GB
  Current LE             37897
  Segments               3
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

Create Partition

mkfs.ext4 -L Archive -m 1 /dev/vgarchive/lvarchive

Partition Tuning

Then I started to tune few parameters in the partition.

Maximum mount count is disabled as I want to know how many times it has been mounted. But it may pose problem when the partition should be checked for errors. Some Linux operating systems check filesystem after an interval of maximum mounts. So, for regular interval check I am going to use time and it has been set to 3 months.

tune2fs -c -1 /dev/vgarchive/lvarchive
tune2fs -i 3m /dev/vgarchive/lvarchive

Reserved 2GB size (524288 blocks) for filesystem operation.
tune2fs -r 524288 /dev/vgarchive/lvarchive

Set default mount options ACL and user_xattr.
tune2fs -o acl,user_xattr /dev/vgarchive/lvarchive

Status of Partition

# tune2fs -l /dev/vgarchive/lvarchive
tune2fs 1.41.9 (22-Aug-2009)
Filesystem volume name:   Archive
Last mounted on:          
Filesystem UUID:          082a3363-078a-47d5-933d-b6f197fe2b1b
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype
                          needs_recovery extent flex_bg sparse_super large_file
                          huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              19406848
Block count:              77613056
Reserved block count:     524288
Free blocks:              76346216
Free inodes:              19406837
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      1005
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
Flex block group size:    16
Filesystem created:       Sun Jan 17 09:27:16 2010
Last mount time:          Sun Jan 17 09:33:15 2010
Last write time:          Sun Jan 17 02:49:06 2010
Mount count:              1
Maximum mount count:      -1
Last checked:             Sun Jan 17 09:27:16 2010
Check interval:           7776000 (3 months)
Next check after:         Sat Apr 17 09:27:16 2010
Lifetime writes:          4872 MB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:              256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
Default directory hash:   half_md4
Directory Hash Seed:      7e31a891-aa72-4c87-81e1-2319d96bd220
Journal backup:           inode blocks
So, thats it. The partition is ready and just need to mount it and move all recovered data here. adiĆ³s por ahora.


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