Installation guide

Release Notes
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4.3.1.1. Merging Snapshots
Red Hat Enterprise Linux 6 introduces the ability to merge a snapshot of a logical volume back into the
origin logical volume. This allows system administrators to revert any changes that have occurred on a
logical volume by merging back to the point preserved by a snapshot.
For more information about the new snapshot merge feature, consult the lvconvert manpage.
4.3.1.2. Four-Volume Mirrors
LVM in Red Hat Enterprise Linux 6 supports creating a logical volume with up to four mirrors.
4.3.1.3. Mirroring Mirror Logs
LVM maintains a small log (on a separate device) which it uses to keep track of which regions are in
sync with the mirror or mirrors. Red Hat Enterprise Linux 6 provides the ability to mirror this log device.
4.3.2. LVM Application Library
Red Hat Enterprise Linux 6 features the new LVM Application Library (lvm2app), allowing the
development of LVM based storage management applications.
5. Power Management
Further Reading
The Power Management Guide
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provides information on effectively managing power
consumption on Red Hat Enterprise Linux 6.
5.1. powertop
The introduction of the tickless kernel in Red Hat Enterprise Linux 6 (refer to Section 12.4.2, “Tickless
Kernel”) allows the CPU to enter the idle state more frequently, reducing power consumption and
improving power management. The new powertop tool provides the ability to identify specific
components of kernel and userspace applications that frequently wake up the CPU. powertop was
used in development to identify and tune many applications in this release, reducing unnecessary
CPU wake up by a factor of 10.
5.2. tuned
tuned is a system tuning daemon that monitors system components and dynamically tunes system
settings. Utilizing ktune (the static mechanism for system tuning), tuned can monitor and tune devices
(e.g. hard disk drives and ethernet devices). Red Hat Enterprise Linux 6 also introduces diskdevstat
for monitoring disk operations and netdevstat for monitoring network operations.
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http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Power_Management_Guide/index.html