Dynamic lun expansion with Volume Manager on RedHat

Problem

Determining that dynamic lun expansion is working can be made by consulting various outputs on RedHat

Solution

The lun in question was originally around 600GB in size. The lun was then resized on the array by a further 100GB. The only command left to run back on the host was:

vxdisk resize sdd (sdd was the device in question).

The various outputs from RedHat and Volume Manager, confirming the new size, are:

a) checking RedHat's /proc/partitions:

8 48 721420288 sdd

b) checking RedHat's fdisk:

Disk /dev/sdd (Sun disk label): 255 heads, 189 sectors, 29935 cylinders

Units = cylinders of 48195 * 512 bytes

Device Flag Start End Blocks Id System

/dev/sdd3 u 0 29935 721358662+ 5 Whole disk

/dev/sdd8 u 0 29935 721358662+ f Unknown

c) Checking Volume Manager's vxscsi:

# /etc/vx/diag.d/vxscsi -g /dev/sdd

geometry of /dev/sdd: nhead=255 nsect=189 ncyl=29937 sectsz=512 rpm=3600 cap=1442840576

d) Checking vxdisk list

# vxdisk list xiv0_1261

Device: xiv0_1261

devicetag: xiv0_1261

type: auto

.

.

public: slice=3 offset=65792 len=1442651520 disk_offset=0

.

e) Checking the OS message log:

messages reports:

Jan 21 23:16:28 vlx40 kernel: SCSI device sdd: 1442840576 512-byte hdwr sec

tors (738734 MB)

Jan 21 23:16:28 vlx40 kernel: sdd: Write Protect is off

Jan 21 23:16:28 vlx40 kernel: SCSI device sdd: drive cache: write through

Jan 21 23:16:28 vlx40 kernel: sdd: detected capacity change from 6528350289

92 to 738734374912

all the above outputs confirm that the lun is now greater than 700GB big

Applies To

RedHat 5.8

Storage Foundation 5.1SP1RP2P3HF3

IBM storage array