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How to Configure Staging to Run Backup with Zmanda?

What is Staging?

A process of moving data from one storage medium to another medium, and then removing the data from its original location is known as staging. The staging reduces the time it takes to complete a backup by directing the initial backup to a high-performance file or device type.

Zmanda Management Console (ZMC), a new Web-based service offers rich and innovative installation, configuration, backup, and reporting tools to greatly simplify the management of Amanda backups.

Regardless of the device type chosen, ZMC also allows you to define an optional write-cache mechanism called a staging area or holding disk. It stores the backup image on the saver’s hard disk. The staging area will help to run backup in parallel to holding disk and the backups will finish in a much smaller window than what it would be if written directly to the device.

This helps in case of device/media failures due to Connection error or running out of tapes in the changer by storing in this staging area. Then these images can be used for recovery and will be moved to the secondary media in next the backup run if the media problem is resolved.

The staging area is used for Amanda DLE (Disk List Entry) only if the whole backup image will fit in the staging area. Otherwise, DLE is directly written to the backup media volume without the use of a staging area. Zmanda recommends the staging area size should be at least the size of one full backup image of all DLEs in the backup set.

Note: The size of the staging area should be at least the size of one full backup size of all DLE’s in the backup set. If the staging size is insufficient, then Zmanda displays an error “insufficient staging area,” and the backup fails.

How to Use Staging?

To use the staging area, it must be enabled while configuring the DLE in the ZMC console.

  • Navigate to “Backup >> What” in ZMC console
  • Expand Advance Options for this Object only
  • Select “use staging, if possible” to enable Staging
  • Select “Never use staging” to disable staging
Use Staging for Backup
  • To view the staging parameters, navigate to “Backup >> Staging” page.
  • The staging tab is where all the staging parameters are defined. Staging is mainly used for S3 and Tape backups, but it can be enabled for Vtape backups as well.
  • In the case of S3 and Vtape backups, the staging configuration is straightforward. The below image is for reference.
Staging Configuration for DB Backup
  • Device Name: The name of the ZMC device used by the backup set. This information cannot be modified on this page
  • Auto Flush: Specifies whether Amanda should flush the backup images from the staging/area holding disk to the backup media before a backup run. The default value is “enabled”.
  • Staging Size Limit: Define how much of the partition should be used for staging. Setting this to “Disabled” will disable the use of staging.
  • Backup runs staged at: This is the absolute path to the staging area where backup images are collected before being archived. The default path is /var/lib/amanda/staging/<backupset name>. This path can be changed; the only condition is that the staging partition should be accessible by the amandabackup
  • Live Statistics: These are calculated automatically by Zmanda and displays the total, free and used spaces in the Staging partition.
  • Reserve for Incremental: When space on a staging area falls below a threshold size (the value of this parameter), Amanda limits itself to performing only incremental backups. A threshold of 20 percent causes Amanda falls back to incremental backups when holding disk(s) free space falls below 20 percent.

Staging for Tape Backups

  • For Tape backups, there are some additional features available in staging. They are defined by a set of Flush parameters. These parameters allow users to utilize their tape storage efficiently.
  • In the case of normal backups without staging, if some space is unused in a Tape, it will not be utilized in the consecutive backup runs.
  • To avoid this wastage of Tape space, we can configure the staging parameters accordingly to utilize the maximum amount of storage. Below image is for reference
Retaining Backups in Staging Area

Flush at:

Default: 0.

  • Amanda will not begin writing data to a new volume until the amount of data on the holding disk is at least this percentage of the volume size, and the criterion for flush-threshold-scheduled is also met.
  • In other words, Amanda will not begin staging until the amount of data on the holding disk is greater than the tape length times this parameter. This parameter may be larger than 100 percent in case if you wish to keep more recent dumps on the holding disk for faster recovery.
  • The value of this parameter may not exceed that of the flush-threshold-scheduled parameter.

Flush Scheduled

Default: 0.

  • Amanda will not begin writing data to a new volume, until the sum of the data on the holding disk and the estimated amount of data remaining to be dumped, is at least this percentage of the volume size and the criterion for flush-threshold-dumped is also met.
  • In other words, Amanda will not begin until the inequality h + s > t × d is satisfied.

Where,

  • h is the amount of data on the holding disk.
  • s is the total amount of data scheduled for this run but not dumped yet.
  • t is the capacity of a volume.
  • d is this parameter, expressed as a percentage (This parameter may be larger than 100 percent).
  • The value of this parameter may not be less than that of the flush-threshold-dumped or taper flush parameters.

Note

Holding disk must be big enough for the above two criteria to be satisfied. If the holding disk is not used (due to no remaining holding space), then Amanda will disregard the constraint specified by this setting and start a new volume anyway.

Taper Flush

Default: 0.

  • At the end of a run, Amanda will start a new tape to flush remaining data if there is more data on the holding disk at the end of a run than this setting allows flushing. The value is specified as a percentage of the capacity of a single volume.
  • In other words, at the end of a run, Amanda will begin a new tape if the inequality h > t × f is satisfied,

Where,

  • h is the amount of data remaining on the holding disk from this or previous runs
  • t is the capacity of a volume.
  • f is this parameter, expressed as a percentage (This parameter may be greater than 100%)
  • d is this parameter, expressed as a percentage (This parameter may be larger than 100 percent).
  • The value of this parameter may not exceed that of the flush-threshold-scheduled parameter. Autoflush must be set to ‘yes’ if taper flush is greater than 0.

Please follow the above steps to prune, drop, and recycle images from the media. In case you get stuck in the process, kindly contact our team.

You can reach us at support@zmanda.com or give us a call at 888-496-2632 (U.S.) or 408-732-3208 (INTL). Be sure to check out our other how-to videos: How To | Create a Windows Template on Zmanda Windows Client and Configure It

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