HP StoreOnce 4430 HP StoreOnce Backup System Concepts and Configuration Guidel - Page 75

Compression and encryption, Verify, Synthetic full backups, Summary of NAS best practices

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Appended backups should not be used because there is no benefit to using the append model, this does not save on disk space used. Compression and encryption Most backup applications provide the option to compress the backup data in software before sending, this should not be implemented. Software compression will have the following negative impacts: 1. Consumption of system resources on the backup server and associated performance impact. 2. Introduction of randomness into the data stream between backups which will reduce the effectiveness of StoreOnce deduplication Some backup applications now also provide software encryption, this technology prevents either the restoration of data to another system or interception of the data during transfer. Unfortunately it also has a very detrimental effect on deduplication as data backed up will look different in every backup preventing the ability to match similar data blocks. The best practice is to disable software encryption and compression for all backups to the HP StoreOnce Backup system. Verify By default most backup applications will perform a verify pass on each back job, in which they read the backup data from the StoreOnce appliance and check against the original data. Due to the nature of deduplication the process of reading data is slower than writing as data needs to be re-hydrated. Thus running a verify will more than double the overall backup time. If possible verify should be disabled for all backup jobs to StoreOnce, but trial restores should still happen on a regular basis. Synthetic full backups Some backup applications have introduced the concept of a "Synthetic Full" backup where after an initial full backup, only file or block based incremental backups are undertaken. The backup application will then construct a full system recovery of a specific point in time from the original full backup and all of the changes up to the specified recovery point. In most cases this model will not work well with a NAS target on a StoreOnce Backup system for one of two reasons. • The backup application may post-process each incremental backup to apply the changes to the original full backup. This will perform a lot of random read and write and write-in-place which will be very inefficient for the deduplication system resulting in poor performance and dedupe ratio. • If the backup application does not post-process the data, then it will need to perform a reconstruction operation on the data when restored, this will need to open and read a large number of incremental backup files that contain only a small amount of the final recovery image, so the access will be very random in nature and therefore a slow operation. An exception to this restriction is the HP Data Protector Synthetic full backup which works well. However the HP Data Protector Virtual Synthetic full backup which uses a distributed file system and creates thousands of open files does not. Check with your backup application or HP Sales person for more details. Summary of NAS best practices • Configure multiple shares and separate data types into their own shares. • Adhere to the suggested maximum number of concurrent operations per share/appliance. • Choose disk container backup file sizes in backup software to meet the maximum size of the backup data. For example, if a full backup is 500GB set the container size to be at least 500GB . If this is not possible, make the backup container size as large as possible. Summary of NAS best practices 75

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Appended backups should not be used because there is no benefit to using the append model,
this does not save on disk space used.
Compression and encryption
Most backup applications provide the option to compress the backup data in software before
sending, this should not be implemented.
Software compression will have the following negative impacts:
1.
Consumption of system resources on the backup server and associated performance impact.
2.
Introduction of randomness into the data stream between backups which will reduce the
effectiveness of StoreOnce deduplication
Some backup applications now also provide software encryption, this technology prevents either
the restoration of data to another system or interception of the data during transfer. Unfortunately
it also has a very detrimental effect on deduplication as data backed up will look different in every
backup preventing the ability to match similar data blocks.
The best practice is to disable software encryption and compression for all backups to the HP
StoreOnce Backup system.
Verify
By default most backup applications will perform a verify pass on each back job, in which they
read the backup data from the StoreOnce appliance and check against the original data.
Due to the nature of deduplication the process of reading data is slower than writing as data needs
to be re-hydrated. Thus running a verify will more than double the overall backup time. If possible
verify should be disabled for all backup jobs to StoreOnce, but trial restores should still happen
on a regular basis.
Synthetic full backups
Some backup applications have introduced the concept of a “Synthetic Full” backup where after
an initial full backup, only file or block based incremental backups are undertaken. The backup
application will then construct a full system recovery of a specific point in time from the original
full backup and all of the changes up to the specified recovery point. In most cases this model will
not work well with a NAS target on a StoreOnce Backup system for one of two reasons.
•
The backup application may post-process each incremental backup to apply the changes to
the original full backup. This will perform a lot of random read and write and write-in-place
which will be very inefficient for the deduplication system resulting in poor performance and
dedupe ratio.
•
If the backup application does not post-process the data, then it will need to perform a
reconstruction operation on the data when restored, this will need to open and read a large
number of incremental backup files that contain only a small amount of the final recovery
image, so the access will be very random in nature and therefore a slow operation.
An exception to this restriction is the HP Data Protector Synthetic full backup which works well.
However the HP Data Protector Virtual Synthetic full backup which uses a distributed file system
and creates thousands of open files does not. Check with your backup application or HP Sales
person for more details.
Summary of NAS best practices
•
Configure multiple shares and separate data types into their own shares.
•
Adhere to the suggested maximum number of concurrent operations per share/appliance.
•
Choose disk container backup file sizes in backup software to meet the maximum size of the
backup data. For example, if a full backup is 500GB set the container size to be at least
500GB . If this is not possible, make the backup container size as large as possible.
Summary of NAS best practices
75