LVM

Then, we'll be ready to test out LVM and get the most out of it.

While the transition to LVM is a bit of an ordeal , once the transition is complete , managing filesystems becomes tremendously easier .

LVM allows you to create logical volumes out of the physical storage resources on your machine.

Logical volume management (LVM) is a way systems can abstract physical volume management into a higher-level and usually simpler paradigm.

The LVM enables the data to be on multiple physical drives, though they might be configured to be on a single volume group.

Layer the Logical Volume Manager (LVM) between the disk and the file system. Doing so allows you to extend the EBS volume at a later time.

First, we need to select the physical storage resources that are going to be used for LVM.

Depending on your LVM version, there may be other LVM-related options that you'll want to enable as well.

By aggregating partitions and whole disks into a virtual disk, LVM can sum small storage spaces into a bigger, consolidated one.

LVM actually controls all the physical disk resources on your system and helps provide a logical view of your storage subsystem.

EVMS calls these final storage objects "logical volumes, " whether they happen actually to be disks, partitions, or LVM logical volumes.

Let's now quickly introduce the elements that are part of LVM, from the bottom up.

If you've never used a form of LVM before, you're in for a treat; it's a wonderful technology.

If you use parted, you can use the set command to turn on the lvm flag, as in set 1 lvm on to flag partition 1 as an LVM partition.

Using this event producer, an application can verify the status of a Volume Group on the disk, with the LVM subsystem.

The latest available Red Hat Exam Prep guide includes LVM requirements on both parts of the RHCE exam.

This section defines the Logical Volume Manager (LVM) and introduces some of its features.

Even though RAID and LVM provide interesting features, XFS is the simplest option for a relatively small EBS volume.

This allows data to reside on multiple physical platters and to be managed and analyzed using specialized LVM commands.

You can resize an existing LVM partition, if it's contiguous with the new space.

LVM consists of two parts: a kernel part and a suite of user-space tools.

As a consequence of the new pbuf pool implementation, AIX displays and manages additional LVM statistics and tuning parameters.

Note that the initial-ramdisk image usually activates LVM only when it detects that the root filesystem is under a VG.

If you plan to have your root filesystem inside an LVM LV, take extra care with the initial-ramdisk image.

The data migration from the old disk to the new disk would be accomplished by the LVM command, migratepv.

This virtual disk, in LVM terms, is called volume group.

Another four volumes were used in an LVM for mail journaling.

It reports on all layers of file system utilization, including the Logical Volume Manager (LVM), virtual memory, and physical disk layers.

The volume group name used to automatically partition using LVM is already in use.

Both filesystem types link their file and directory data to the structure used by the AIX LVM for storage and retrieval.

What you find is that as a practical matter, AIX LVM is really more like VERITAS, but without the premium price and third party issues.

LVM uses this area to keep track of how the physical extents are allocated, among other things.

The LVM system will then allocate storage from the volume group we specify and create our new volume, which is now ready for use.

LVM is an AIX disk management system that maps the data between logical and physical storage.

You can even use the AIX LVM to migrate to a completely new SAN storage subsystem (see Resources).

Behind the scenes, the LVM system allocates storage in equal-sized "chunks" , called extents.

You may select partitions on RAID and LVM devices as well as those created directly on disks.

LVM allows admins to manage their storage resources with much greater flexibly than the traditional method of using static disk partitions.

From here, you can create a volume group, add to an existing volume group, or remove a volume from the LVM altogether.

The command shown in Listing 10 takes a snapshot of LVM information every second for 10 intervals.

An LVM configuration makes it possible to combine disk space from several small disks into one big logical volume.

Logical Volume Management (LVM) is new to RHEL 3 and is more important than the prerequisite skills covered in most of this chapter.

Now, let's take a look at how LVM solves these problems.

Using your favorite partitioner (fdisk, parted, gparted), create a new partition for LVM usage.

Because all disks are already under the control of the LVM, you don't need to partition nor define disk as being under a volume manager.

However, paging space can be manipulated with some of the more specialized LVM commands, such as moving them from disk to disk.

LVM provides the ability to dynamically add and remove storage to the DS4500 without interrupting service to the running cluster.

This is, in fact, a standard best practice if you want to perform consistent backups over a database using LVM snapshots.

One of the most important services available in Linux is the Logical Volume Manager (LVM).

It's similar to kvpm in that it provides point-and-click access to LVM management, including resizing operations.

From the earliest days of AIX, the LVM has made management of disks, logical volumes, and file systems easy.

We capture the current disk and volume group configuration with several LVM commands.

The other partitions, including the swap partition, will be created inside the LVM partition.

The AIX LVM provides a simple way of moving large amounts of data from one LPAR to another.

Congratulations -- you now have kernel LVM support enabled; now, we need to get the user-space tools compiled and installed.

Of the two, system-config-lvm provides a somewhat simpler and friendlier user interface; however, either will get the job done.

Fortunately, the AIX LVM is a very mature, stable and robust tool.

You can also create logical volume management (LVM) and RAID configurations much as you would on MBR disks.

It's a very robust implementation of LVM, though it does have its issues.

There is a good workaround for this limitation, provided you are familiar with the underlying LVM tools.

You can create a new partition in the empty space and add the new partition to your LVM.

It means that thanks to EVMS, you can use a single tool to partition disks, create LVM objects, and even create Linux software RAID volumes.

Next article, I'll show you how to create your own logical volumes and unleash the power of LVM.

LVM provides an abstraction to the underlying storage.

Above the menu a summary of the LVM configuration is shown.

The current disk, LVM and SDD (vpath) configuration was also captured.

There were two LVM utilities at the core of our data migration strategy (mirrorvg and migratepv).

If you want to use the latest LVM version, you'll want to apply patches from the LVM tarball to your current 2. 4 kernel source tree.

Volume management is handled by installing LVM on the cluster.

You will find SMIT refreshing and appreciate the integration of the AIX filesystem with their LVM.

In the future, we'll tackle more great stuff, including LVM, the iptables firewall and many other exciting projects.

Next, you'll see the tools needed for filesystem and Logical Volume Management (LVM).

Our first step in setting up LVM involves properly initializing these partitions so that they can be recognized by the LVM system.

You will also need a fairly recent version of either GRUB or LILO if you plan to boot from an LVM or RAID disk.

As we continue to maintain our volume, we'll need to use both the software RAID and LVM tools as necessary.

It can also see that I've used these partitions to create LVM logical volumes.

To create an LVM logical volume, we follow a three-step process.

In this step, if you don't want use LVM to manage your root partition, then you can ignore copying lvm, vgscan, vgchange, and related lib.

With LVM, you can remove a PV from a VG in the same way they are added (that means online! ).

Andreas Dilger is involved with the Linux LVM project and has a nice-looking online ext2 filesystem resizer.

In the tutorial, I only briefly mentioned RAID and LVM.

To mirror and use LVM without VERITAS, you would have to bring these filesystems under the control of SVM.

However, you may not want to use the LVM support included with your stock (or distribution-supplied) 2. 4 kernel.

Before we actually get LVM up and running, I'm going to explain exactly what it is and how it works.

This article focuses on steps 1 and 3, which address the AIX-specific procedures at the LVM level.

It is fully backwards-compatible with the original LVM toolset.

OK, you now have a kernel that's been patched so that it has the most current LVM code available.

How to extend the file system to keep up with growing storage demands using the hot-add feature of the LVM.

If you choose to install SLES 9 or 10, all of your LVM partitions will be erased.

Certainly it's good that improvements were made in LVM, but in most cases, AIX already had these features.

While LVM is running, we can add physical volumes to the volume group or even remove them.

Figure 1 shows system-config-lvm in action.

You can make it read-only at the LVM level by appending a -p r to the lvcreate command.

If you use LVM, you should also install lvm2 before you reboot as the 2. 6 Kernel does not directly support LVM1.

Using LVM, we can reduce the outage required for migrating the data.

However, with LVM there is a better approach.

You do the same with gdisk, except that its type code for LVM partitions is 8e00.

Included in newer Linux kernels, able to host LVM physical volumes, the other is

Implementation of the Disaster-Tolerant System Transport Protocol Based on LVM

To prepare the unit for LVM, create a primary LVM partition (partition type 8e) spanning the whole disk

To initialize a partition to support LVM volumes

Shows LVM device structure, names and sizes of logical volumes and more

After you've created a partition, you should see one (or more) Linux LVM partitions in your partition table