Needed explaination with example "pvmove -a" command

[Samckoyur]

Hello Everyone,

Can anyone explain me with example how "pvmove -a" commmand works in 3 differnet way it is suggested by LVM SAG.

Below are the three different way to execute this command:

• pvmove –a vg_name

• pvmove –a lv_path [pv_path | pvg_name]

• pvmove –a –f pv_path

Regards,

Yadu

[Patrick Wallek]

The '-a' is the "automatic rebalance" mode for LVM 2.0 and higher volume groups.  Have a read through the "Auto-Rebalance Mode" section of the pvmove man page and see if that helps.

As far as your question --

-a vgname -- will rebalance the VG as a whole

-a lv_path -- will rebalance only the specified LV across all PV's or the specified PV or PVG.

-a -f pv_path -- The -f option in conjunction with -a option can be used to move all the used extents from a single or multiple physical volumes to the remaining physical volumes in the volume group such that the remaining physical volumes are balanced with respect to space utilization.

[Samckoyur]

I tried to do this while reading the System Administrator Guide for LVM.

please check my commands and please tell me where I am wrong or whats needs to be correct

# vgdisplay -v vg03
--- Volume groups ---
VG Name                     /dev/vg03
VG Write Access       read/write
VG Status                   available
Max LV                       511
Cur LV                        3
Open LV                    3
Max PV                     511
Cur PV                      1
Act PV                      1
Max PE per PV       524288
VGDA                        2
PE Size (Mbytes)    32
Total PE                   1067
Alloc PE                   3
Free PE                    1064
Total PVG                 0
Total Spare PVs      0
Total Spare PVs in use      0
VG Version                  2.0
VG Max Size                 1p
VG Max Extents              33554432

   --- Logical volumes ---
   LV Name                     /dev/vg03/lvoltest3
   LV Status                   available/syncd
   LV Size (Mbytes)            32
   Current LE                  1
   Allocated PE                1
   Used PV                     1

   LV Name                     /dev/vg03/lvoltest4
   LV Status                   available/syncd
   LV Size (Mbytes)            32
   Current LE                  1
   Allocated PE                1
   Used PV                     1

   LV Name                     /dev/vg03/lvoltest5
   LV Status                   available/syncd
   LV Size (Mbytes)            32
   Current LE                  1
   Allocated PE                1
   Used PV                     1


   --- Physical volumes ---
   PV Name                     /dev/disk/disk15
   PV Status                   available
   Total PE                    1067
   Free PE                     1064
   Autoswitch                  On
   Proactive Polling           On


#pvmove -a vg03
Automatic re-balance operation can not balance beyond the current
configuration.

Please suggest

Thanks in advance!

[Patrick Wallek]

It appears that you have only a single PV in this VG.  In that case I don't think there is much rebalancing that can be done.  I don't see how you could rebalance only on a single PV.

[Patrick Wallek]

Take a look at the "HP-UX System Administrator's Guide: Logical Volume Management HP-UX 11i Version 3" here:

https://h20565.www2.hp.com/portal/site/hpsc/template.BINARYPORTLET/public/kb/docDisplay/resource.process/?spf_p.tpst=kbDocDisplay_ws_BI&spf_p.rid_kbDocDisplay=docDisplayResURL&javax.portlet.begCacheTok=com.vignette.cachetoken&spf_p.rst_kbDocDisplay=wsrp-resourceState%3DdocId%253Demr_na-c02023734%257CdocLocale%253Den&javax.portlet.endCacheTok=com.vignette.cachetoken

There is a section "Moving Data for Disk Space Balancing: Auto Re-balancing" that starts on page 75 of that manual.

[Samckoyur]

---

@Patrick Wallek wrote:

It appears that you have only a single PV in this VG.  In that case I don't think there is much rebalancing that can be done.  I don't see how you could rebalance only on a single PV.

---

Hi Patrick,

Thanks for your quick response!

I have these many disk:

# ioscan -m dsf
Persistent DSF           Legacy DSF(s)
========================================
/dev/rdisk/disk8         /dev/rdsk/c0t0d0
/dev/rdisk/disk8_p1      /dev/rdsk/c0t0d0s1
/dev/rdisk/disk8_p2      /dev/rdsk/c0t0d0s2
/dev/rdisk/disk8_p3      /dev/rdsk/c0t0d0s3
/dev/rdisk/disk9         /dev/rdsk/c0t0d1
/dev/rdisk/disk10        /dev/rdsk/c0t0d2
/dev/rdisk/disk11        /dev/rdsk/c0t0d3
/dev/rdisk/disk12        /dev/rdsk/c0t0d4
/dev/rdisk/disk13        /dev/rdsk/c0t0d5
/dev/rdisk/disk14        /dev/rdsk/c0t0d6
/dev/rdisk/disk15        /dev/rdsk/c0t0d7
/dev/rdisk/disk17        /dev/rdsk/c1t0d0

now can you suggest what to do and how to do.

Thanks in advance!

[Torsten.]

Looks like there is a single disk only in this VG.

Balancing means, if you have for example a VG with a single disk and you add another disk, all the extends will be balanced across both disks.

Could you please post

# ioscan -fnN

[Samckoyur]

---

@Torsten. wrote:

Looks like there is a single disk only in this VG.

Balancing means, if you have for example a VG with a single disk and you add another disk, all the extends will be balanced across both disks.

Could you please post

# ioscan -fnN

---

Hi Torsten

Please find the attached output files.

Thanks in advance!

[Torsten. · Accepted solution]

disk15 is a single LUN provided by your smartarray P400 controller. Because the VG has a single LUN only, there is nothing to re-balance.