Installation guide

Chapter 21. Online Storage Management
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Note
In order to resize an online file system, the file system must not reside on a partitioned device.
21.14.1. 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.
21.14.2. 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
3
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 Section 21.12, “ Scanning iSCSI
Interconnects”).
• It re-scans for new/modified logical units the same way that the command echo 1 > /sys/
block/sdX/device/rescan does. Note that this command is the same one used for re-
scanning fibre-channel logical units.
21.14.3. Updating the Size of Your Multipath Device
If multipathing is enabled on your system, you will also need to reflect the change in logical unit size to
the logical unit's corresponding multipath device (after resizing the logical unit). For Red Hat Enterprise
Linux 5.3 (or later), you can do this through multipathd. To do so, first ensure that multipathd