Resizing An Online Logical Unit; Resizing Fibre Channel Logical Units; Resizing An Iscsi Logical Unit - Red Hat ENTERPRISE LINUX 5.5 - ONLINE STORAGE GUIDE Manual

14. Resizing an Online Logical Unit

In most cases, fully resizing an online logical unit involves two things: resizing the logical unit itself
and reflecting the size change in the corresponding multipath device (if multipathing is enabled on the
system).
To resize the online logical unit, start by modifying the logical unit size through the array management
interface of your storage device. This procedure differs with each array; as such, consult your storage
array vendor documentation for more information on this.
Note
In order to resize an online file system, the file system must not reside on a partitioned
device.

14.1. Resizing Fibre Channel Logical Units

After modifying the online logical unit size, re-scan the logical unit to ensure that the system detects
the updated size. To do this for Fibre Channel logical units, use the following command:
echo 1 > /sys/block/sdX/device/rescan
Important
To re-scan fibre channel logical units on a system that uses multipathing, execute the
aforementioned command for each sd device (i.e. sd1, sd2, and so on) that represents a
path for the multipathed logical unit. To determine which devices are paths for a multipath
logical unit, use multipath -ll; then, find the entry that matches the logical unit being
resized. It is advisable that you refer to the WWID of each entry to make it easier to find
which one matches the logical unit being resized.

14.2. Resizing an iSCSI Logical Unit

After modifying the online logical unit size, re-scan the logical unit to ensure that the system detects
the updated size. To do this for iSCSI devices, use the following command:
iscsiadm -m node --targetname target_name -R
Replace target_name with the name of the target where the device is located.
Note
You can also re-scan iSCSI logical units using the following command:
iscsiadm -m node -R -I interface
Replace interface with the corresponding interface name of the resized logical unit (for
example, iface0). This command performs two operations:
• It scans for new devices in the same way that the command echo "- - -" > /
sys/class/scsi_host/host/scan does (refer to
Interconnects").
Resizing an Online Logical Unit
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Section 12, " Scanning iSCSI
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