You can improve the performance of data movement operations using the parameters
described below. Use one or more parameters to improve the performance.
The throughput to a storage media depends on the speed at which chunks are written
to that media and the number of entries per chunk in the Index Cache. Increasing
the CHUNK SIZE improves the throughput to a storage media.
However the disadvantage is that granular restores (e.g., single file restore)
will be slower. On the other hand large restores, like a full machine rebuild will
be a bit faster.
By default, the chunk size is configured to get the optimal throughput to the
storage media.
The following table gives default chunk size for tape and disk backups and the
recommended range of chunk size:
Storage Media
Backup Type
Default Chunk Size
Recommended Range of Chunk Size
Tape
Granular Backup
4 GB
8 GB, 16 GB, 32 GB
Database Backup
16 GB
8 GB, 16 GB, 32 GB
Disk and Optical
All Backups
2 GB
----
Direct Attached NDMP
All backups
4 GB
----
Do not reduce the default chunk size if you want to
perform data movement using NDMP Remote Server (NRS).
For more information about modifying the chunk size, refer to
Increasing
Chunk Size.
Use the following registry key to modify the chunk size:
Increase the block size for faster write operations to tape media. The default
block size for write operation is 64 KB.
For more information about modifying the block size, refer to
Increasing Block Size. You can also use setFlushBlockSize
tool available in the Resource Pack to modify the block size.
Before increasing the block size, ensure that the following criteria are satisfied:
New block size is supported by the Host Bus Adapter Driver installed in
the MediaAgent and the tape device.
All the MediaAgents associated with a Storage Policy supports the block
size configured on that storage policy
If different MediaAgents are used for backup and restore operations and
the backup MediaAgent has higher block size, then ensure that the restore MediaAgent
is configured with Host Bus Adapters and tape drives that are able to read the
data written with higher block size.
If you want to modify the block size, use the following supported values
of block size:
MediaAgent
Supported Block Size
Windows 2000 MediaAgent with direct attached SCSI devices
The Job Controller window displays all the current jobs
in the CommCell. A status bar at the bottom of the job controller shows:
The total amount of jobs
The amount of jobs that are running, pending, waiting, queued and
suspended
The high and low watermarks.
This information is updated at the close of each chunk, or within 5-minute
intervals; whichever occurs sooner.
When larger CHUNKS are configured for data movement operations the amount
of time between Job Manager Updates is automatically extended by that configuration.
Modify this interval to increase the performance of data
movement operations. Follow the steps given below to modify the interval:
From the CommCell Browser, right-click the CommServe icon, and then
click Control Panel.
Double-click Job Management.
Click Job Updates tab.
In the Protection (Mins) column, type or click to increase
the integer value, to modify the update interval for data protection
jobs.
In Recovery(Mins)) column, type or click to increase the integer
value, to modify the update interval for data recovery jobs
In the State update interval for ContinuousDataReplicator
box, click the integer value in the box to change the time.
The Collect File records the path and name of each scanned file that is included
in the backup. When you are performing backup of a large data, a large collect files
are generated. You can divide the content in more number of collect files and reduce
the time taken by a data reader to read the collect file.
By default, the number of collect files is equal to twice the number of data
readers (2 x Number of Data Readers). 2 is a multiplication factor which is the
number of Collect files that will be created for the job. You can change the multiplication
factor.
Use the following registry key to modify the multiplication factor:
The Network Agents establish data pipes to transfer data from the client to the
MediaAgent. Therefore, increasing the number of Network Agents will increase the
data transfer throughput from the client.
If required, modify the other network parameters of
the client, such as network card speed, network switch speed etc., to get
the optimum data transfer throughput.
Follow the steps given below to increase the data transfer throughput:
From the CommCell Browser, navigate to <Client> |
<Agent> | defaultBackupSet.
Right-click the <subclient> or <instance>
and then click Properties.
Click Storage Devices tab and then click the Data Transfer
Options tab.
Enter the number of network agents in the Network Agents
box.
The default value is 2. You can set the value to 2 or 4.
Click OK to save your changes.
Increasing Network Agents on a MediaAgent
If you increase the number of network agents on a MediaAgent, more CPU cycles
and RAM are consumed. This will result into less number of backups getting completed
on the MediaAgent. If you are expecting additional backup operation on a MediaAgent,
it is recommended to set Network Agents to 1.
The Data pipe buffers determine the amount of shared memory allocated on each
computer for data pipes. The size of each buffer is 64K. By default, 30 data pipe
buffers are established on each server for data movement operations. You can increase
the data transfer throughput from the client by increasing the number of data pipe
buffers.
Use the following registry key to modify the data pipe buffers:
When you increase the number of data pipe buffers, more shared memory is consumed
by the client or MediaAgent. This may degrade the server performance. Therefore,
before increasing the number of data pipe buffers, ensure that the adequate shared
memory is available. You can optimize the number of data pipe buffers by monitoring
the number of concurrent backups completed on the server.
When the MediaAgent and CommServe are installed on Windows Server 2003 or 2008,
follow the steps given below to improve the performance of background services:
Open the System Properties dialog box.
Click Advanced tab.
Under Performance, click Settings.
Click Advanced tab on the Performance Options dialog
box.
Follow the steps given below to improve the data movement for a File System
iDataAgent:
It is recommended to verify the disk performance using the DiskReadWrite
utility available in resource pack. For more information, refer to
Resource
Pack.
If the client computer has multiple disks, create multiple subclients. This
will enable the parallel data movement operations from the client.
If the Storage Policy is not
configured for multiple data streams, then subclients will perform the data
protection operations one after the other in a serial.
For Windows and Unix File System iDataAgent,
configure the subclient for multi-stream backups. By default, multi-streaming
is not configured for clients with a single disk. However, you can choose to
override the default configuration. For more information, refer to
Automatic File System Multi-Streaming.
HP-UX File System
For the HP-UX 11i v3 file system, do the following steps to improve the performance
of backup operations.
Install the PHKL_41700 patch.
The
select(2) system call enhancement is delivered
through the PHKL_41700 patch.
Enable the hires_timeout_enable kernel parameter
kctune hires_timeout_enable=1
The select(2)code has been modified to use the
high resolution timer functionality. The applications which use
select(2)and specify small timeouts will timeout
right after the specified duration and this will reduce the long wait time. With
this higher resolution, the timer API interfaces can support time intervals less
than the current 10 ms. The hires_timeout_enable
parameter changes take effect immediately. So it can be done while the server is
up and running.
Exchange Mailbox data movement operations are constrained by the Microsoft MAPI
API which limits data movement operations to an average of 2GB per hour per stream.
This mode of data movement actually logs into each mailbox and scans each piece
of mail as it is delivered to the Inbox.
You can improve the performance of data movement operations by creating multiple
subclients. This will enable parallel data movement operations. However, the cumulative
throughput of the Exchange server may decrease if sufficient system resources are
not available. Therefore create user-defined subclients to divide mailbox backups
into groups based on specific criteria. For more information, refer to
Grouping Mailboxes Into User-Defined Subclients.
You can optimize the performance of data movement operations using the following
methods:
Defragmenting the Disk
If the disk is highly fragmented disk the size of the data in backup is significantly
larger than the valid data on the client computer. This will increase the time required
for data movement operation and also consume more space on the storage media.
Configuring the Disk Extent Size Parameter for Windows
The Image Level iDataAgent backs up
extents on the source drive. The default value is 512KB. You can change the disk
extent size to improve the performance of data movement operations. The supported
values are 64KB, 128KB, 256KB, 512KB and 1 MB. The value must be power of 2.
Consider the size of the volume to be protected by the Image Level
iDataAgent relative to the size of the
extent to be used. For example, a 512KB extent setting against a backup of 10KB
of data is backed up entirely, including all of the empty blocks of data (502KB
of data).
When you are changing the extent size, keep in mind that:
Backup extent size must be uniform across source and destination computers
and not larger than the size of the source volume.
In a clustered environment, all of the physical nodes must have the same
Backup extent size.
Once the disk extent size is reconfigured any incremental and differential
backups completed prior to the reconfiguration are lost. The next data movement
operation will be converted to a FULL.
You must restart the client after changing the extent size.
Configuring the Disk Extent Size Parameter for Unix
The Image Level iDataAgent backs up
extents on the source drive. The default value is 2MB (4096 X 512 bytes). You can
change the disk extent size to improve the performance of data movement operations.
The supported values are 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, etc.
The value must be power of 2.
Consider the size of the volume to be protected by the Image Level
iDataAgent relative to the size of the
extent to be used. For example, a 512KB extent setting against a backup of 10KB
of data is backed up entirely, including all of the empty blocks of data (502KB
of data).
128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, etc. The
value must be power of 2.
When you are changing the extent size, keep in mind that:
Backup extent size must be uniform across source and destination computers
and not larger than the size of the source volume.
In a clustered environment, all of the physical nodes must have the same
Backup extent size.
For Image Level backups for Linux or Solaris client servers, the extent
size can only be changed when the CXBF device is configured. To modify the extent
size of an existing CXBF device, the server administrator should first de-configure
the CXBF device and reconfigure with the new extent size.
If the source volume has high levels of disk fragmentation or small average
file sizes, use lower values extent size.
Once the CXBF device is reconfigured any incremental and differential backups
completed prior to the reconfiguration are lost. The next data movement operation
will be converted to a FULL.
You can improve the performance of backup and restore operations by modifying
the following parameters for Oracle iDataAgent:
Parameter
Default Value
Description
Number of data files and archive files to be included in each RMAN backup
set
32
Increase the value of this parameter for faster backups. However, increasing
the value in this parameter will create additional CPU overhead in order
to optimize the population of the Archive file. The granular restore
of individual table spaces and data files will be slower.
Number of open data files that can be read by RMAN during the backup
8
Reduce the value of this parameter for faster backup and less system
load on the Oracle server.
Maximum size of data blocks used during backups
262144 KB
Increase the value of this parameter for faster tape drives or magnetic
libraries.
For Example: For SDLT or LTO tape drives, a minimum value of
1048576 (1MB) is recommended.
Also, if you are experiencing performance issues during backup, you can troubleshoot
them by enabling logging of performance details in the log files. These performance
counters contain information that help in resolving the performance related issues
during backups. See
Troubleshooting Performance Issues for more information.
You can optimize the performance by modifying the following parameters for Informix
iDataAgent:
Adjusting Buffer Size
You can modify the buffer size settings using the BAR_XFER_BUF_SIZE parameter
in the $ONCONFIF file on the database server. For best performance of data movement
operations set the value to 30.
Configuring On-Bar Parameters
You can also configure the following parameters on the Informix database server:
Parameter
Description
BAR_IDLE_TIMEOUT
This parameter specifies the maximum number of minutes that an ON-Bar
worker process is idle before it is shut down.
BAR_MAX_BACKUP
This parameter specifies the maximum number of backup processes per
ON–Bar command. You can control parallel execution of ON–Bar processes using
this configuration parameter.
BAR_NB_XPORT_COUNT
This parameter specifies the number of shared-memory data buffers for
each backup or restore process.
BAR_PROGRESS_FREQ
This parameter specifies how frequently the backup or restore progress
messages display in the activity log.
LTAPEBLK
This parameter specifies the block size for logical-log backups made
with ontape, onload, onunload.
LTAPEDEV
This parameter specifies the tape device used for logical-log backups
made with ontape.
TAPESIZE
This parameter specifies tape size for logical-log backups made with
ontape.
You can improve the data movement performance by reviewing the following parameters
in the Netware Server environment:
Verifying Network Connectivity
Verify the Network Interface Card (NIC) settings for the Novell Client severs,
MediaAgents, CommServe, Routers, Network Switches. Client server side NIC settings
are found in MONITOR.NLM, although the name of the statistic varies between LAN
drivers.
Ensure that each port is configured for Full Duplex connectivity. Half-Duplex
network connections create an increase in IP stack collisions and reduces data movement
efficiency.
Using Novell's Storage Management Services to Optimize the Backups
You can tune the Novell Netware v6.5 NSS volumes for better data movement operations
by adjusting the parameters mentioned below. It is recommended to consult with the
Netware Administrator before adjusting any parameters for Novell Netware v6.5 NSS
volume. For more information about Best Practices for NSS volume performance tuning,
refer to
http://support.novell.com/cgi-bin/search/searchtid.cgi?/10065215.htm.
You can use the following file to update these parameters:
C:\NWSERVER\NSSSTART.CFG
Parameter
Recommended Value
Description
NameCacheSize
2000
OpenFileHashShift
15
You can increase the value of this parameter up to 17 if 1GB of memory
is available.
CacheBalance
80
The Cache Balance refers to Cache Balance Percent. You can find the
Cache Balance Percent in Monitor | Server Parameters |
Novell Storage Services.
The Cache Balance configured on the NetWare
client server should be equal to the percent of total disk space mounted
on the server that belongs to NSS.
ClosedFileCacheSize
100000
You can increase the value of this parameter up to 100000 if 1GB of
memory is available.
Resolving GroupWise Performance Issues
Use the /nosalvage switch on GroupWise volumes
to prevent the volumes from filling with deleted message files. This will give similar
effect as PurgeImmediate attribute on traditional
volumes. The FileFlushTimer and
BufferFlushTimer switches should not be used for
data movement operations. These settings can stagnate migration of clustered volumes
and may result into data loss in the event of an abnormal termination on the server.
You can improve the performance of data movement operation for NDMP and NRS clients
using the following guidelines:
Turn off the File History on the appliance.
Ensure that the MediaAgent managing NDMP operations does not reside on the
CommServe
Ensure that multiple data streams are used for data transfer to the MediaAgent.
If the tape is attached to a NAS client, the indexing operation is completed
on the MediaAgent. Ensure that the MediaAgent has sufficient memory available
for indexing.
Use the syssat command to review the CPU consumption.
When the backup is running, use the following command to fetch information
about MediaAgent performance.
netstat -a
The send_q information will determine whether
network queues are becoming full.
Tuning the Performance of NetApp as a Magnetic or Disk Library
Follow the guidelines given below to improve the performance of the NetApp Magnetic
or Disk Library:
Do not fill an aggregate more than 90% of capacity, as there is a sharp
decline in performance when an aggregate is too full.
Configure backup volumes or LUNs with 0% fractional reserve, 0% snap reserve,
and snapshots disabled. Refer to NetApp Support TR 3348 for descriptions associated
with each of these settings:
http://media.netapp.com/documents/tr-3348.pdf
When you are configuring a large disk library, maintain individual LUN sizes
in 4-8 TB range. You can scale down if only a small TB footprint will be used
for storage on disk.
If you are using iSCSI LUNs and not Fiber Channel ones, refer to NetApp
Support technical report 3749 for additional background.
http://media.netapp.com/documents/tr-3749.pdf
. This report provides information regarding NetApp performance and LAN configuration
that can help you with the CommVault Media Agent configuration.
Don not Thin provision LUNs or Volumes, which will be disk library
mount points. This will increases the write overhead on the NetApp appliance.
When backups are running, the controllers will be allocating space for the volume
at the same time as the write operations are occurring.
Improving Performance of NetApp Restore Operations
Follow the guideline given below to improve performance of restore operations
for NetApp File Server:
Before performing the Direct Access Restore, refer to FAQs for NAS
iDataAgent.
Create multiple subclients before performing the backup.
Do not use the nRESTORELIMIT registry key
to improve the performance of restore operation for NetApp File Server. When
you are restoring of a single directory, the list of items to restore contains
1 entry. The nRESTORELIMIT is used to change
the number of items sent in each restore request. For the the default value
is 8192 entries. Therefore, unless the you select more than 8192 items for restore
there is no need to use the nRESTORELIMIT key.
You can improve the performance of Auxiliary Copy operation using the following
guidelines:
Configuring an Alert
The Auxiliary copy operation enables you to create a secondary copies of data
associated with a storage policy. When the data to be copied exceeds a specific
threshold or if the data is not copied for specific number of days, you can get
a notification. Once you get the notification, you can optimize and troubleshoot
the auxiliary copy operation.
You can enable an alert to get the notification and set the thresholds. For more
information, refer to
Best
Practices.
Optimizing the Auxiliary Copy Operation for Disk
When you are copying the data to a magnetic disk, you can improve the performance
by increasing the chunk size. For more information, refer to
Improving the Throughput
to Storage Media.
It is recommended to verify the disk performance using the DiskReadWrite
utility available in resource pack. For more information, refer to
Resource
Pack.
A fragmented disk performs slow read operations. For more information on
disk fragmentation, refer to
Fragmentation Analysis.
Optimizing the Auxiliary Copy Operation for Tapes
Validate the drives before performing any data protection operation. For
more information, refer to
Validating Drives in a Library.
Check if the software and hardware compression is enabled for the jobs to
be copied. For more information, refer to
Data Compression.
Review the Auxiliary Copy logs to determine if the same media is mounted
multiple times.
You can reduce the time required for data movement to tape using multiplexing
to stream the data. You can determine the multiplexing factor by analyzing the network
configuration and the required disk throughput.
Typical multiplexing factors are set between 2 and 5 on 100BaseT networks.
Typical multiplexing factors are set between 5 and 8 on 1000BaseT networks.
The encrypted data movement operation is always slower than an unencrypted data
movement operation. The software based encryption consumes CPU resources. Therefore,
it is recommended to perform the encryption of the data on the system that has the
maximum CPU resources available.
You can select the method of encryption from several algorithms and key length
options. For more information about Configuration options, refer to
Data Encryption.
It is recommended to select specific data from a client for encryption, instead
of performing bulk encryption for the client. Do not encrypt Windows executable
and programs and similar object types.
The size of shared index cache depends on the condition of the file system on
which the Shared Index Cache resides and also the input/output supported by the
MediaAgent. For large cache, the Disk I/O the becomes an issue. Therefore, RAID0,
RAID1, or RAID5 are preferred schemes to define a speedy location for the cache.
RAID 1 is the fastest and safest. RAID 5 is fast and inexpensive.
Follow the guidelines listed below while creating a Shared Index Cache Directory
for alternate data paths:
Ensure that all the MediaAgents that will be configured as data path candidates,
point to the same network share and the same folder within this network share
for its index cache location.
If you have both the Unix and Windows MediaAgents pointing to the same folder,
make sure that the files and folders are accessible to both these operating
systems.
For MediaAgents that access the Shared Index Cache Directory across domains,
make sure that two-way trust relationships between the domains are established.
If you reboot a Unix MediaAgent, verify and ensure that the mount point
to the index cache folder is mounted in same location specified in this Catalog
tab of the MediaAgent Properties dialog box.
For a Network Shares, if the shared index cache location is changed, then
the change must be reflected on all the MediaAgents using the network share.
If the cloud connectivity is via very high speed network of about 1 GB per second
or higher, follow the below recommendations to get the maximum performance for the
cloud based backup/restore/auxcopy jobs.
These settings will consume large amounts of memory
on the MediaAgents and and an x64 MediaAgent is mandatory to support it.
Hence these settings are not recommended for low speed networks.
Check the latest installed service pack. A minimum service pack level of
SP6a is required on the MediaAgents and CommServe.
Check Cloud performance specific Registry Keys are set correctly on MediaAgent.
Check the list below for Backup and Restore.
Check Storage Policy copy -> Data Path property -> set Chunk Size to 2 GB
Check Storage Policy copy -> Data Path property -> Set Block size to 1024k
Check Number of Streams is set to 10 or higher in Storage Policy properties
Check Sub client property -> Number of Data Readers and set to higher value
(example 10) and enable “Allow multiple data readers within a drive or mount
point” check box.
Following are the Cloud performance specific Registry Keys for cloud based backup
jobs:
You can select the following overwrite options from the Restore Options dialog
box.
Unconditional Overwrite
Overwrite if file on media is newer
Whenever you select any of these options, large files on the destination computer
will be deleted. If set the following option ON, the operating system on the destination
computer will perform bulk deletion and not the sequential deletion:
