TECHNICAL BRIEF
Written by
Quest Software, Inc.
Five Tech Tips for Effective Backup and Recovery in Virtual
Environments using vRanger
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 1
Contents Abstract .......................................................................................................................................................................... 2
Five Tips for Effective Backup and Recovery ................................................................................................................. 3
1. Use vRanger to minimize the amount of data protected. ........................................................................................ 3
2. Maximize backup speed and shrink your backup window using vRanger. ............................................................. 6
3. Take advantage of intelligent, image-level restore. ................................................................................................ 8
4. Protect to fit your needs and SLAs. ........................................................................................................................ 9
5. Minimize the performance impact to the virtual platform environment. ................................................................. 11
Conclusion ................................................................................................................................................................... 14
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 2
Abstract Virtualization is being adopted rapidly in many IT infrastructures, bringing significant time, money, and labor savings
to procurement, administration, deployment, operation, reliability and recoverability. But like any new technology,
virtualization has introduced new challenges despite solving critical problems—particularly in smaller organizations
where time and money are always at a premium.
This tech brief discusses five key areas to help you better protect your virtualized data and restore the benefits of
virtualization for your IT infrastructure using vRanger.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 3
Five Tips for Effective Backup and Recovery Quest’s data protection experts have five technical tips for effective backup and recovery in virtual environments
using vRanger. These tips will help you avoid the growing pains and challenges that keep you from fully protecting
your virtual assets and infrastructure.
1. Use vRanger to minimize the amount of data protected vRanger can reduce the amount of data you back up by using technologies that filter out unchanged and deleted
data. While tools that utilize VMware Change Block Tracking (CBT) eliminate the need to scan to find changed
blocks, CBT does not prevent the backup and restore of deleted data. The Windows operating system never fully
removes the space that is occupied by deleted data; the data is not deleted until it’s overwritten to make space for
new data, or is overwritten with zeros.
Unfortunately, those files are seen as changed data blocks, and backup tools using only CBT will back up that
deleted data. VMs hosting applications with frequently changing data may hold gigabytes of deleted data, resulting in
longer backup windows and large backup archives.
vRanger has a patent pending technology called Active Block Mapping (ABM). ABM allows vRanger to map the
contents of the Windows file system to the outside of the virtual disk. This mapping allows vRanger to understand
which blocks of a virtual disk make up deleted data and skip these blocks. The process to create this mapping is 100
percent agentless, does NOT require login access to the running VM, and takes less than 10 seconds to complete.
The steps to using ABM in vRanger are:
1. Create a vRanger backup job.
2. Check the ABM option on the Options selection of the vRanger job, as shown in the figure below.
Note that you must be running ESX and your file system must be basic and of MFT type.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 4
Figure 1. Selecting the ABM option in vRanger
Storage Footprint and Backup Time Results
The following figure shows the archive footprint for backups of 35 VMs with and without ABM:
Figure 2. Using ABM reduces archive size significantly.
0
20
40
60
80
100
120
ABM Enabled ABM Disabled
Archive Size Archive Size in GB
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 5
The figure below shows the backup times for backups of 35 VMs with and without ABM:
Figure 3. Using ABM reduces backup times.
1:06
1:09
1:12
1:14
1:17
1:20
1:23
1:26
ABM Enabled ABM Disabled
ABM ON|OFFBackup Time
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 6
2. Maximize backup speed and shrink your backup window using vRanger Another strategy to increase backup speed and shrink backup windows is to use vRanger to perform simultaneous
backup and restore.
Many backup applications on the market today only perform a single task for one job at a time. For example, if you
create a job of 35 VMs, these products will perform only one task at a time. The vendors tell you that if you want to do
more, just create more jobs. However, this leaves you with two problems:
More management overhead
No control should these jobs over run your environment
vRanger’s Resource Manager, on the other hand, enables you to do many or just a few backups and restores at one
time, regardless of whether you have one job or 10 jobs. The following figure shows the Resource Manager
configuration options:
Figure 4. vRanger Resource Manager configuration options and their default values
Maximum number of tasks running on vRanger (default: 100) – This controls how many backups, restores and
replications run at one time. It’s unlikely that you will ever need to raise the default.
Maximum number of tasks running off a LUN (default: 3) – This controls how many backups, restores and
replications run at one time from a single datastore. This is important because you don’t want to cripple your storage
with too many reads or writes. Also, because vRanger uses VMware snapshots to back up and replicate VMs, you
don’t want to open too many snapshots on a single VMware datastore. If you have SAS storage or fiber storage, you
could raise this value to 5; if you’re running iSCSI, you should leave this setting at 3. Just remember this setting is
global for all datastores; use the setting appropriate for your slowest datastore.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 7
Maximum number of tasks running on a host (default: 1) – This controls how many backups, restores and
replications run from a single host. The safe maximum number is 2.
Maximum number of tasks running per repository (default: 3) – This controls how many backups and restores
happen at one time from a single repository. This setting is important because vRanger can send data very quickly to
your repository and you need to know how much data your target is able to handle. For example, when you’re not
using iSCSI, vRanger can send a single backup stream about 20-40 MB/s. So if your target only has a single 1 GB
network card, how many backups would it take to full the entire pipe? A 1 GB NIC is 1024 Mb/s and a single backup
stream can send 160 Mb/s – 320 MB/s. vRanger default settings allow between 480 Mb/s – 960 Mb/s. If you want to
do more, the best approach is to bind two network cards for speed on your target repository. You should do this by
binding two 1-GB NICs on the repository and in your network switch. If you do this correctly in Windows, the network
status indicator will show 2 GB. This will allow for twice as many backups at one time, so you should be able to raise
the setting from the default of 3 to 6 tasks per repository.
Maximum number of tasks running locally (default: 3) – This setting controls the number of backups that run
locally, such as LAN-free from a physical host, LAN-free in a VM, ESXi network backups, or using vRanger’s
HOTADD to a network target. The rule of thumb here is to take the number of CPUs you have and subtract one for
the vRanger service and OS. You can perform one backup per core when backing over fiber on a physical host.
When performing LAN-free in a VM or HOTADD to a network target, you can get two backups per core.
Backup and Restore Time Results
The figure below shows how vRanger reduces the backup time by performing multiple backups at once:
Figure 5. By performing multiple backups at once, vRanger reduces backup times dramatically.
0:00:00
0:28:48
0:57:36
1:26:24
1:55:12
2:24:00
2:52:48
3:21:36
3:50:24
4:19:12
1 @ a time 6 @ a time
Backup TimeBackup Time
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 8
The figure below shows similar results for restore time:
Figure 6. vRanger can perform multiple restores at one, reducing restore time.
3. Take advantage of intelligent, image-level restore Incremental backups have a bad rap because most backup products have to restore the full backup entirely, and then
restore each incremental over the top of the full. This way of using incremental backups is flawed: if your full backup
is, say, 10 GB and your incremental backups comprise 5 GB of changes, they will replace 5 GB of the full. That
means you have 15 GB of total network transfer and 15 GB of disk writes.
vRanger enables you to avoid this problem completely and make good use of incremental backups. vRanger knows
where all of the blocks are located in each archive file. When a restore is done as per the preceding example,
vRanger will send only 10 GB total of network transfer and 10 GB of disk writes. Because of this technology,
vRanger’s incremental restores have overhead than a normal full backup and restore.
0:00:00
0:14:24
0:28:48
0:43:12
0:57:36
1:12:00
1:26:24
1:40:48
1:55:12
2:09:36
1 @ a time 6 @ a time
Restore TimeRestore Time
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 9
The figure below shows the overhead of a restore using a typical backup solution, and then using vRanger, which has
no overhead.
Figure 7. vRanger’s optimized restore has no overhead, reducing bandwidth use and restore times.
4. Protect to fit your needs vRanger uses VMware snapshot process to perform image-level backup of VMs. Unlike other solutions, this enables
vRanger to back up virtual machines without interruption,
Let’s review the snapshot process that allows for image-level backup. When a VM is running, its virtual disks are
locked by the hypervisor and cannot be read. When a snapshot is added to the VM, VMware unlocks the VM’s virtual
disks by sending all the writes to the virtual disk to a delta file on the datastore. This freezes the base virtual disk to a
point in time; now the VM is reading from both base virtual disk but is writing all changes to a delta file.
At this point, the base virtual disk can be read by vRanger. After it is done with the base virtual disk, vRanger will
send a commit commend to VMware to close the open delta. VMware will then add another delta and commit the first
delta that grew during the backup window. Once the first delta is committed to the base disk, the second delta is
closed very quickly because it was open only for the length of time it took for the original delta to close.
vRanger also has safeguards in place in case something stops vRanger from closing the open snapshots. If vRanger
sees a snapshot that had not been newly created, it will be closed so that the open snapshot does not harm the
running VM.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 10
The figure below shows a VM’s file layout before a snapshot is opened:
Figure 8. A VM’s file layout before a snapshot is opened
The figure below shows the VM’s file layout after a snapshot is opened:
Figure 9. A VM’s file layout after a snapshot is opened shows increased resource need
To help with snapshot health on VMware, you should commit a set of sources to the ESX(i) host to ensure it has the
resources needed to close snapshots in a timely manner. You should give the ESX(i) host ―System Resource
Allocation‖ 800 MB of RAM and 1500 dedicated. This will ensure that no matter how big your VM density gets, your
host will have the resources it needs to manage itself, including snapshots. Without this allocation, your VMs could
freeze and drop off the network when snapshots are opened and closed.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 11
The figure below shows where to set dedicated resources for a host to ensure snapshot health:
Figure 10. Setting dedicated resources for a host to ensure snapshot health
5. Minimize the performance impact to the virtual platform environment When you have physical hosts, using an agent-based approach to backup and recovery is fine because the agent
uses only a small amount of resources on that single physical host. But when you run multiple VMs on a single
physical host, each VM has its own agent, and each agent uses CPU cycles and memory. This causes significant
management overhead and resource usage on the physical host.
Accordingly, vRanger takes an agentless approach to backup and recovery. Image-level backup, image-level restore,
file-level restore from an image, and mailbox- and message-level restore are all 100 percent agentless. Therefore,
the vRanger server does not need to talk to running VMs over the network, nor does it need guest credentials.
vRanger only needs accounts and IP access for Virtual Center and ESX(i) hosts to perform image-level backup and
image-level restore.
The charts below illustrate the performance gains from eliminating agents.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 12
This figure shows a host with just 10 idle VMs without agents installed:
Figure 11. A host with just 10 idle VMs without agents installed
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 13
This figure shows a host using greater CPU cycles with just 10 idle VMs with agents installed:
Figure 12. A host with 10 idle VMs with agents installed
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 14
Conclusion When you virtualize your physical infrastructure, you will find your data accumulation and network bandwidth
utilization growing even faster than before. This can result in longer backup windows and overloaded networks. The
five tips in this paper for effective backup and recovery in virtual environments, gleaned from the experience of
Quest’s vRanger experts, will help you backup and restore as fast as possible.
Five Tech Tips for Effective Backup and Recovery in Virtual Environments using vRanger 15
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TECHNICAL BRIEF
About Quest Software, Inc.
Quest Software (Nasdaq: QSFT) simplifies and reduces the cost of managing IT for more
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