Chapter 5 - Managing On-line Indexes
This chapter describes EBR' s powerful index management features for managing on-line indexes manually. You may also configure an EBR service to manage indexes automatically using the Policies dialog box. For more information on tape rotation and automatic index management, see Chapter 4.
This chapter describes the following concepts and procedures for index management:
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On-line indexes ![]()
Save sets ![]()
Examining the contents of an index ![]()
Checking an index ![]()
Reclaiming space for an index ![]()
Removing cycles from index save sets
This chapter also contains the following instructions for managing backup volumes:
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Examining the contents of a backup volume ![]()
Changing its location and mode ![]()
Removing a volume from the media set
Each EBR service maintains two types of indexes: a file index and a media index. The file index stores information about the files backed up by the service, whereas the media index maps the backed-up files to backup volumes. The EBR service stores these indexes on the server file system and uses them to locate the files users request for recovery.
Each entry in the file index typically includes the following information for a backed-up file: filename, number of blocks, access permissions, number of links, owner, group, size, last modified time, and backup time.
The file index changes with each backup, as entries for the newly backed-up files are inserted. As long as an entry for a file remains in the file index and the backup volume is not damaged, the file may be recovered. The EBR service maintains one file index for each of its clients.
The media index is usually much smaller than the file index. The media index maps each file to the backup volume or volumes where it is stored. EBR uses the media index to tell you (by means of the Pending window) which backup volume to mount during a recover. Each EBR service maintains media information for all of its clients in a single media index.
The file and media indexes require disk space. The media index is usually small, but the file indexes typically require 5% to 10% of the total file space for all clients being backed up. The size of an index is proportional to the number of entries stored in it.
Every version of a file that you want to be able to locate through the recover browser (an attribute called browsability) costs 220 bytes of index space. The more frequently a file changes and the more frequently it is backed up, the more versions of the file are listed in the index and the more space the index consumes.
For example, if you perform a full backup once a week and incremental back ups once a day, a file that never changes occupies only 220 bytes of index space per full backup, or 880 bytes each month (220 bytes times 4 for each index created when the file was saved). Using that same schedule, a file that changes every day consumes 6820 bytes of index space each month (220 bytes for each of the 31 indexes created when the file was saved).
With EBR Administrator's Policies, Indexes, and Volumes dialog boxes, you can:
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Create policies for automatic index management ![]()
Monitor the contents of the indexes ![]()
Select entries for removal, and ![]()
Mark backup volumes as recyclable
Save sets are groups of files that an EBR service backs up as a unit. They are usually contained in a single disk volume. Save sets are created each time a backup is started. Generating a save set creates entries in both the file and media indexes.
To conserve index and backup volume space, EBR provides a variety of backup levels. For example, a full backup contains all files in a given file system; an incremental backup contains only the files that have changed since the previous backup. Services and file service directories often contain some files that do not change and files that do change. Therefore, incremental backups, which contain only files that have changed, conserve both index and volume space.
See Chapter 4 for more information on backup levels.
To recover a complete directory or service, in most cases some files will need to be restored from a full backup, and others from one or more incremental backups. Without the underlying full backup, the data cannot be completely recovered. Without the incremental backups, only the old version of the data can be recovered. The incremental backups depend on the full backup.
Both the full and incremental backups are needed to recover a complete directory. Therefore, EBR Administrator checks these dependencies when save sets are removed, either manually or automatically. A save set will not be automatically removed and cannot be manually removed until all of its dependent save sets have been removed.
The following diagram shows the relationship between incremental and full backups.
To summarize, incremental backups are dependent upon the previous full backup. A save set cannot be removed until all of its dependent save sets have been removed.
There are five actions that can be performed on an index: inserting entries, browsing, removing entries, reclaiming space, and cross-checking.
Inserting entries in an index occurs automatically during backup. The EBR service inserts entries into pre-allocated free space in the indexes. If there is no free space in an index, space is acquired from the file system to hold the new entries. The index will grow larger.
Browsing the file index occurs when EBR displays the Recover window to help locate a file, when the server console recover browser is in use, or when EBR Administrator displays the Index Save Sets dialog box to show client save sets. Browsing the media index occurs when EBR Administrator displays the Volume Save Sets dialog box to show the contents of a backup volume. Browsing neither increases nor decreases the size of an index. When browsing an index, you are looking through the index for information concerning saved files or the contents of backup volumes.
Removing entries frees space in the index. The free space is used when new entries are inserted. EBR Administrator automatically removes entries based upon the length of time you decide to store them in the index, using the Browse and Retention policies. Entries may also be removed manually either by selecting Remove Oldest Cycle in the Index Save Sets dialog box, or Remove Volume in the Volumes dialog box.
Reclaiming space returns the empty space, created when entries are removed from the index, to the file system. It occurs either automatically as defined by the index policies, or manually with the Reclaim space command in the Indexes dialog box.
Cross-checking an index checks the status of a client's file index against the media index. This process is done using the Cross-Check Index button in the Indexes dialog box.
You can always use the Policies and Clients commands to configure the EBR service so it automatically maintains your on-line indexes at a steady size, containing only the most current backups. Automatic index management is performed after the completion of a group backup.
Using the Indexes and Volumes commands, you can manually remove entries for save sets from the file index, or remove entries for backup volumes from the media index. For instructions on creating policies that automatically manage your indexes, see Chapter 4.
To manage your file indexes manually, choose Indexes from the Client menu. Or click the Indexes button on the speedbar. The Indexes dialog box appears:
The Indexes dialog box displays a list of client file indexes maintained by the EBR service. Remember, each client that the service backs up has its own index. The Indexes dialog box also displays the following information about each client's file index:
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Size - The current allocated size of the client's file index ![]()
Used - The percentage of this space actually used by the entries in the file index Note: If you see 100% displayed in the Used column, it does not mean that the index is full and no other file entries can be added. It means that 100% of the currently allocated space is used. Index size may increase as needed, up to a maximum of 2 gigabytes per client.
To free up disk space, click the Reclaim Space button. This action decreases the size of the highlighted client's file index by compressing the space in the index left by removed entries. Users cannot back up or recover files during a Reclaim Space operation.
Click the Cross-Check Index button when you want to compare the index records for backed-up files to the records in the media index. Use this command, for example, if you cancel a backup after it has started and you wish to verify the integrity of the on-line indexes.
Highlighting a client in the Indexes dialog box and clicking Show Save Sets displays the Index Save Sets contained in the file index for that client. Save sets are grouped according to their unique save set names. For example, all backups of C: in a client's file index are grouped under the C: save set.
Index Save Sets provides the following information about a client's save sets:
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Size - The amount of index space used by the save set group in the client's file index, in kilobytes. ![]()
Cycles - The number of cycles of the save set contained in the client's file index. A cycle starts with a full backup and ends just before the next full backup. Cycles include all the incremental and level 1 to 9 backups, if any exist, between the two full backups. Zero cycles indicate that a full cycle has not yet completed.
You may remove the oldest full cycle to conserve index space.
Highlighting a save set and clicking the Remove Oldest Cycle button removes the oldest full-to-full cycle of the highlighted save set. The Remove Oldest Cycle command and the Reclaim Space command (in the Indexes dialog box) are described in detail on the following pages.
Clicking the Remove Oldest Cycle button displays a message box saying the operation is underway. Clicking the Reclaim Space button displays a message box saying that it may take considerable time to reclaim the index space. The EBR service displays a message box during index operations because it can perform only one index operation at a time.
You may complete administration tasks, backups, or recovers during an index operation, but not another index operation. The messages for index operations follow:
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This message appears before you start an index operation: Reclaiming space may take considerable time.
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These messages appear after you commit to the operation.
Day of the week is Monday through Sunday and hh:mm uses the 24 hour clock for hours and minutes:Started removing oldest cycle at day of week hh:min
Started reclaiming space at day of week hh:min
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This message appears when another index operation is in progress: Index is currently busy
To remove the oldest full-to-full cycle of a save set from the file index for a client, select the save set in the Index Save Sets dialog box and click Remove Oldest Cycle or press the [Enter] key. A message box appears, from which you can cancel the operation.
Note that removing index entries does not decrease the size of the index file; it still takes up as much space as it did before. To decrease the amount of space the index uses, use the Reclaim Space command in the Indexes dialog box, after removing a cycle.
Tip: The previous full cycle may not be removed using Remove Oldest Cycle, because recent backups depend upon it.
The following diagram illustrates what happens when you remove a cycle from the index. Removing the oldest cycle opens up space so that other entries can fit there without increasing the size of the index.
To reclaim empty space created in the client's file index when entries are removed (either automatically with Policies or manually with Remove Oldest Cycle), use the Reclaim Space command.
Important: You may not simultaneously Reclaim Space and Remove Oldest Cycle for one client. The index will be busy during both operations.
To start the Reclaim Space operation, highlight the name of a client in the Indexes dialog box and click Reclaim Space. EBR Administrator displays the following message box:
To perform the operation, click Yes or press the [Enter] key. The Reclaim Space dialog box appears:
A percentage bar tells you how the operation is progressing. You may close the dialog box without canceling the Reclaim Space operation by clicking the Close button.
The diagram that follows illustrates what happens when you use the Reclaim Space command. The index is re-written without deleted entries, thus shrinking its size and opening up space for new entries. The space is returned to the file system.
Tip: Reclaim Space requires extra disk space to operate because it makes a reduced-size copy of the file index. In general, you need a little more than the percent Used of total index Size (both shown in the Indexes dialog box).
After Remove Oldest Cycle or Reclaim Space finishes, EBR Administrator updates the Index dialog box to reflect the current state of the file index.
EBR Administrator marks a backup volume as recyclable when all its save sets have passed the time period designated by the Retention policy. A recyclable volume is eligible for overwriting with new backups. You may want to force a backup volume to be recyclable sooner than it would automatically become available for overwriting.
Using the Volumes dialog box, you can manually mark backup volumes as recyclable, which also marks all the save sets on the volume as recyclable. You may also set a location for a backup volume, change the mode of a volume, or remove a volume from the media index.
The Volumes dialog box displays information about backup volumes and their save sets for the current EBR service. Highlighting a volume and clicking Show Save Sets opens the Volume Save Sets dialog box for that volume where you see the details of backup volume contents.
To look at or manage your backup volumes, open the Volumes dialog box by selecting Volumes from the Server menu. Or click the Volumes button on the speedbar. The Volumes dialog box appears:
The information in the Volumes dialog box is retrieved from the media index, and provides the following information about each backup volume:
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The Name of the volume, as labeled with the Label command. |
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The media Pool to which this volume belongs. |
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The amount of data Written onto the volume, in kilobytes. If the Written and Used fields are blank, the volume is unused. |
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The percentage of the backup volume Used computed as a percentage of total capacity. If the capacity exceeds 100%, it is because the tape has more capacity than the default capacity EBR Administrator has assigned to it, or because the tape drive is compressing files as they are backed up. |
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The Mode of the volume, either appendable, full, or recyclable. Appendable means that there is room for more data on the volume. Full means that there is no more room for data on the volume, and that the save sets have not yet passed the time period specified by the Browse and Retention policies. Recyclable means that all save sets on the volume have passed both the Browse and Retention policies and are eligible for overwriting, or that you changed the mode of a volume to recyclable. |
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The Location of the volume is optional information that you may enter to serve as a reminder of where your volumes are physically located. |
You can view information about the save sets stored on a backup volume in the Volume Save Sets dialog box.
To open this dialog box, highlight a backup volume in the Volumes dialog box and click the Show Save Sets button or press the [Enter] key. The Volume Save Sets dialog box appears:
The Volume Save Sets list provides the following information about each save set stored on a volume:
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The name of each Client machine in the save set. ![]()
The Date that the save set was backed up. ![]()
The Level of backup that generated the save set. Backup levels apply only to scheduled backups. If no level is listed, the save set was generated by a manual backup. ![]()
The Status of the save set. The save set status may be either browsable, retrievable, recyclable, or incomplete. (See the following descriptions.)
Browsable status means that the save set has an entry in the file index for the client because it has not passed the time period specified by the Browse policy for the client. The files contained in a browsable save set can be browsed and marked for recovery.
Retrievable status means that the entry for the save set has been removed from the client's file index, either automatically due to the client's Browse policy or manually using the Remove Volume or Remove Oldest Cycle commands.
Recyclable status for a save set means that it has passed both the Browse and Retention policies time period, and is now eligible for overwriting.
Incomplete status means that the save set was canceled while in progress, or failed to complete successfully.![]()
The Path of the save set.
Setting the Location for Your Backup Volumes
As an optional reminder to yourself, you can set a location for a backup volume. Setting a location will help you find a backup volume when you need it to recover a file. A location can be a numbered bin, shelf, or any place that you physically store backup media.
To set the location for a backup volume:
1. Highlight a backup volume in the Volumes dialog box.
2. Click the Set Location button. The Set Location dialog box appears:
If the backup volume already has a location, it appears in the Location field and you may then change it.
3. Enter the location of the backup volume, or select a location from the list. The list shows all the previously set locations for volumes.
4. Click OK or press the [Enter] key to designate this location for the selected backup volume. The Volumes dialog box is updated to reflect the location for that backup volume.
Tip: When an EBR service requests that you mount a backup volume during a recovery, you can find it by referring to its location in the Volumes dialog box.
Changing the Mode of a Backup Volume
The mode of a backup volume determines whether the EBR service can write to it during a backup. There are three possible modes for a backup volume:
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Appendable - There is space on the backup volume for more backups. The EBR service can append data to the backup volume and will use this backup volume for backups. ![]()
Full - The capacity of the backup volume has been reached. The default capacity is used unless a different capacity is specified. Default capacity is determined by the device type.
A backup volume may also be in full mode if an "end-of-tape error" is encountered during a backup. If this happens, the EBR service marks the volume as full and then continues the backup on the next appendable volume or requests a new writable volume.![]()
Recyclable - The volume is eligible to be re-labeled and re-used, but its name remains in the media index. You can manually mark a volume as recyclable by changing its mode. If a backup volume's mode is changed to recyclable, all save sets stored on that volume are marked as recyclable. Note: A backup volume is automatically marked as recyclable if all the save sets on the volume are recyclable. Recyclable save sets have passed the time period designated by the Retention policy for that client.
You can manually change the mode of a full or an appendable backup volume to recyclable, and the EBR service will mark its existing save sets as recyclable. When you mount a recyclable backup volume, it will automatically be mounted read-only, so that data will not be accidentally overwritten.
Tip: If you really want to overwrite data on a recyclable volume, you need to re-label that volume.
To change the mode of a volume to recyclable so that it can be overwritten with new backups:
1. Highlight a volume that is in either full or appendable mode in the Volumes dialog box and click the Change Mode button. EBR Administrator displays the Change Mode message box:
2. Click Yes or press the [Enter] key if you want to change the mode of the selected volume to recyclable. Notice that the mode of the volume changes to recyclable in the Volumes dialog box. Click No to leave the mode unchanged.
If you change your mind, you can reset the mode of a recyclable volume using Change Mode. EBR Administrator "remembers" the mode of a volume before it was changed to recyclable and resets it to the previous mode.
In effect, appendable and full volumes change to recyclable, while recyclable volumes revert to their previous state. You cannot change a volume from full to appendable. However, EBR Administrator automatically changes volumes from appendable to full.
To reset the mode of a backup volume:
1. Highlight a backup volume that is in recyclable mode in the Volumes dialog box and click the Change Mode button.
2. Click Yes in the Change Mode message box if you want to reset the mode of the selected volume to its previous mode, either full or appendable. Click No to leave the mode recyclable.
Important: When you manually change the mode of a volume to recyclable from the Volumes dialog box, all of its save sets are given recyclable status, regardless of their relationship to the Browse or Retention policies specified in the Clients dialog box. If you are not certain you want all save sets to be recyclable, do not change the mode.
Removing a backup volume occurs in two stages:
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Remove entries from the appropriate file indexes. This changes the status of the browsable save sets to retrievable. At that point, you may no longer browse and recover these files from a server or workstation client. ![]()
Remove the name of the backup volume from the media index, thus destroying all record of it. You should remove a backup volume from the media index only if you will never need the volume again, or if the volume has been physically damaged and is unusable.
You will seldom need to remove a backup volume from the media index, because removal does not free up much space. Furthermore, leaving a volume in the media index prevents you from accidentally labeling another volume with its name. It is a good idea to put old tapes on a shelf somewhere, and set their location as a reminder of where you left them.
You may still recover a volume you have removed, as long as it has not been recycled yet.
Tip: If a backup volume is lost or destroyed, you should remove it from both the on-line file and media indexes. Otherwise, the EBR service may request the backup volume to be mounted on the server's device during a recover.
To remove a backup volume' s entries from the file index only, complete these steps:
1. In the Volumes dialog box, highlight the volume that you want to remove.
2. Click the Remove Volume button. EBR Administrator displays the Remove Volume dialog box:
3. Under Remove, leave the On-line Index Entries Only button selected, which is the default.
4. Click OK to remove entries for the files stored on the volume from the appropriate file indexes. The status of the save sets containing these files change to retrievable in the Volume Save Sets dialog box. A message box appears during the operation to inform you of progress of the remove operation.
Click Cancel if you do not want to remove the entries from the file indexes.
If you decide to remove the entries from the media indexes as well, click the On-line and Media Index Entries button. Follow these steps:
1. In the Volumes dialog box, highlight the volume that you want to remove.
2. Click the Remove Volume button to bring up that dialog box.
3. Under Remove, click On-line and Media Index Entries button instead of On-line Index Entries Only, which is the default.
4. Click OK to remove the backup volume from the media index for the server. All record of the data on this backup volume is removed from EBR's indexes.
Click Cancel if you do not want to remove the volume from the server's media index.