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Re: [linux-lvm] LVM Volume Size Question



Francois,

Here is the output you requested:
mythserver michael # vgdisplay -v vg
    Using volume group(s) on command line
    Finding volume group "vg"
  --- Volume group ---
  VG Name               vg
  System ID
  Format                lvm2
  Metadata Areas        4
  Metadata Sequence No  10
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               1.59 TB
  PE Size               4.00 MB
  Total PE              417316
  Alloc PE / Size       417024 / 1.59 TB
  Free  PE / Size       292 / 1.14 GB
  VG UUID               2a2Vzo-3HUx-gUU0-EYk3-md1s-PgAg-MM0bQ6

  --- Logical volume ---
  LV Name                /dev/vg/myth
  VG Name                vg
  LV UUID                4Auu9y-47vW-6BBd-Rdd5-PP63-3sYB-lvmNmQ
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.59 TB
  Current LE             417024
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:0

  --- Physical volumes ---
  PV Name               /dev/sdc1
  PV UUID               DX11mo-r0Eh-jN5N-objS-oqo6-eVSU-MShkS2
  PV Status             allocatable
  Total PE / Free PE    238466 / 0

  PV Name               /dev/sdb1
  PV UUID               SetyUA-DkWL-zDDo-W8Om-3avR-nJH8-OnUujv
  PV Status             allocatable
  Total PE / Free PE    178850 / 292

mythserver michael # lvdisplay /dev/vg/myth
  --- Logical volume ---
  LV Name                /dev/vg/myth
  VG Name                vg
  LV UUID                4Auu9y-47vW-6BBd-Rdd5-PP63-3sYB-lvmNmQ
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.59 TB
  Current LE             417024
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:0


So it does appear that /dev/vg/myth is the full 1.59TB.  Any reason that it appears that the output of df does not agree with this or am I confused?

Regarding your recommended steps, I understand that those steps will not eliminate my reliance on the two drives not failing but the steps will setup a stripped mapping which can improve performance, right?

In my situation, the directory mapped to /dev/vg/myth is just used to store recorded programs from mythtv.  Therefore, the data is not critical, but the desire is to present a directory that is as big as possible to allow mythtv to not run out of recording space (I think 1.6TB should do it!!!).

Also, I assume that the second "dd" command line you wrote should have referenced /dev/sdc and not sdb, correct?

Thanks a ton for your insight.

Take it easy,
Mike




On Fri 09/01/23 10:44 , "F-D. Cami" fcami winsoft fr sent:

Hi Mike,

Could you give us the output of :

vgdisplay -v vg
lvdisplay /dev/vg/myth

I think your myth LV is already 1.5TB, so you only need to run :
# mount -o remount,resize /dev/vg/myth
for the JFS filesystem to be resized.
Please backup everything before running that :)

However, since what you're doing essentially amounts to RAID0 without the
performance benefits (if you lose one drive, your data is lost), I'd run a full backup
and run the following commands to create a striped LV :

lvremove /dev/vg/myth
vgremove vg
pvremove /dev/sdb1
pvremove /dev/sdc1
dd if=/dev/zero of=/dev/sdb bs=4096 count=10000
dd if=/dev/zero of=/dev/sdb bs=4096 count=10000
pvcreate /dev/sdb
pvcreate /dev/sdc
vgcreate vg /dev/sdb /dev/sdc
lcreate -i 2 -I 8 -L 1700M -n myth vg /dev/sdb /dev/sdc
(adjust 1700 to whatever your drives will take)
mkfs.jfs /dev/vg/myth

You will lose a bit of space but gain some performance ; the available VG size can
then be used for other LVs or snapshots.

Best,

Francois



On Fri, 23 Jan 2009 11:14:35 -0600
ctd minneapolish3 com wrote:

> Hey there,
>
>
>
> I have most likely a simple question concerning LVM that I figured someone might be able to provide some insight into.
>
>
>
> I just setup LVM with both /dev/sdb1 and /dev/sdc1 being assigned to my “vg” volume group. There is only one logical volume “myth” off of “vg”.
>
>
>
> My steps:
>
> fdisk /dev/sdc [created 1 partition to span the entire drive of type 8e]
> emerge lvm2
> vgscan
> vgchange -a y
> pvcreate /dev/sdc1
> vgcreate vg /dev/sdc1
> lvcreate -L900GB -nmyth vg
> mkfs.jfs /dev/vg/myth
> fdisk /dev/sdb [created 1 partition to span the entire drive of type 8e]
> pvcreate /dev/sdb1
> vgextend vg /dev/sdb1
> lvextend -L+700G /dev/vg/myth
>
>
> Sdb1: 700GB drive with one partition
>
> Sdd1: 1TB drive with one partition
>
>
> My question is related to the space available in /dev/vg/myth. I
> would assume that I should have ~1.7TB of space on that logical
> partition, but df does not seems to indicate that.
>
>
> # df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> …
> /dev/mapper/vg-myth  943656628 544996248 398660380  58% /mnt/store
> …
> mythserver michael # pvdisplay /dev/sdb1
>   --- Physical volume ---
>   PV Name               /dev/sdb1
>   VG Name               vg
>   PV Size               698.64 GB / not usable 2.34 MB
>   Allocatable           yes
>   PE Size (KByte)       4096
>   Total PE              178850
>   Free PE               292
>   Allocated PE          178558
>   PV UUID               SetyUA-DkWL-zDDo-Wm-3avR-nJH8-OnUujv
> mythserver michael # pvdisplay /dev/sdc1
>   --- Physical volume ---
>   PV Name               /dev/sdc1
>   VG Name               vg
>   PV Size               931.51 GB / not usable 3.19 MB
>   Allocatable           yes (but full)
>   PE Size (KByte)       4096
>   Total PE              238466
>   Free PE               0
>   Allocated PE          238466
>   PV UUID               DX11mo-r0Eh-jN5N-objS-oqo6-eVSU-MShkS2
> mythserver michael # lvextend -L+700G /dev/vg/myth
>   Extending logical volume myth to 2.27 TB
>   Insufficient free space: 179200 extents needed, but only 292 available
>
> I am guessing that I should have run these commands to extend the logical volume to its desired size:
> vgextend vg /dev/sdb1
> lvextend -L+700G /dev/vg/myth
>
> before creating the filesystem with this command which I am guessing locked the size to the 900GB with I used in my setup steps
> mkfs.jfs /dev/vg/myth
>
>
> Does that sound like my issue?
>
> Any thoughts on how to get out of this situation while ensuring no loss of my data that currently resides on /dev/mapper/vg-myth?
>
>
> I am thinking that the following steps should work:
> Copy all of my files on /dev/mapper/vg-myth to other paritions (I
> assume the call to mkfs.jfs below will delete all the contents of this
> partition)
> "lvreduce -L-641G /dev/vg/myth" (to get the size matched up with 931GB + 698GB [ 2.27TB – 931GB – 698GB)
> "mkfs.jfs /dev/vg/myth" (recreate the filesystem now that the size has been corrected)
> remount /dev/vg/myth
> copy back the files
>
> Thanks in advance
> Mike
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm redhat com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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