Resizing Software RAID Arrays with mdadm
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Resizing Software RAID Arrays
with mdadm
This section describes how to increase or reduce the size of a software RAID 1, 4, 5, or 6 device
with the Multiple Device Administration (
mdadm(8)
) tool.
WARNING:
Before starting any of the tasks described in this chapter, make sure that you have a
valid backup of all of the data.
Section 8.1, “Understanding the Resizing Process,” on page 91
Section 8.2, “Increasing the Size of a Software RAID,” on page 92
Section 8.3, “Decreasing the Size of a Software RAID,” on page 96
8.1 Understanding the Resizing Process
Resizing an existing software RAID device involves growing or shrinking the space contributed by
each component partition.
Section 8.1.1, “Guidelines for Resizing a Software RAID,” on page 91
Section 8.1.2, “Overview of Tasks,” on page 92
8.1.1 Guidelines for Resizing a Software RAID
The
mdadm(8)
tool supports resizing only for software RAID levels 1, 4, 5, and 6. These RAID
levels provide disk fault tolerance so that one component partition can be removed at a time for
resizing. In principle, it is possible to perform a hot resize for RAID partitions, but you must take
extra care for your data when doing so.
The file system that resides on the RAID must also be able to be resized in order to take advantage
of the changes in available space on the device. In SUSE
®
Linux Enterprise Server 10 SP1, file
system resizing utilities are available for file systems Ext2, Ext3, JFS, and ReiserFS. The utilities
support growing and shrinking the size as follows:
Table 8-1
File System Support for Resizing
Resizing any partition or file system involves some risks that can potentially result in losing data.
WARNING:
To avoid data loss, make sure to back up your data before you begin any resizing task.
File System
Utility
Increase Size
Decrease Size
Ext2 or Ext3
resize2fs
Yes, offline only
Yes, offline only
JFS
mount -o remount,resize Yes, online only
No
ReiserFS
resize_reiserfs
Yes, online or offline
Yes, offline only
Summary of Contents for LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE 7-2007
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