Q & A
www.ahsay.com Tips On Temporary Directory Setup For Your Backup Set | 1
Tips On Temporary Directory Setup For Your Backup Set
1. How does AhsayOBM/AhsayACB use the temporary directory?
AhsayOBM/AhsayACB makes use of the temporary directory for both backup and restore jobs.
For a backup job, it is used to temporarily store the:
The setup of the temporary directory is an often overlooked and customers typically tend to use
the default setting which is fine for simple file or cloud file backup sets. But for non-file backup
sets like databases or virtual machines this is a very important backup set setting. The location of
the temporary directory and or the free space allocated to the temporary directory can make or
break a successful backup (and restore) and impact on the overall performance.
Backup set index files, an updated set of index files is generated after each backup. The index files
are synchronized to each backup destination at the end of each backup job.
File list.
Incremental/differential delta files generated during backups.
For some backup sets, i.e. VMware (non-VDDK) or database the actual database files will be spooled
to the temporary folder (AhsayOBM makes a copy of the entire database and saves the database
files in the temporary directory) in order to achieve a consistent snapshot for backups.
For a restore job, it is used to temporarily store the:
Full and incremental/differential delta files retrieved from the backup destination.
Merging of full incremental/differential delta files as part of the restore process.
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2. What factors determine the disk space usage or free space required for the temporary directory?
The following factors will have to be taken into account when determining the free space required for
the temporary directory drive or partition:
1. Backup set type:
2. In-file delta - Delta ratio setting
For database backup sets; MS SQL Server in ODBC mode or Lotus Domino/Oracle/MySQL on Linux
platform, AhsayOBM needs to makes a copy of the entire database in the temporary directory. The
free space required on temporary directory must be at least equal to the size of the database you
have selected for backup. For example, if you intend to make a backup of a 1TB MS SQL Server
database in ODBC mode, the location where you define temporary directory must have at least 1TB
of free disk space to accommodate the database file(s).
The default “Delta ratio” setting is 50% for all backup set types, which means that
AhsayOBM/AhsayACB can generate an incremental or differential delta of up to 50% of the full file
size. If you are backing up a very large files or databases, for example a backup of a 1TB database,
then you will need to reserve up to 500GB of free space in drive where your temporary directory is
located in order to accommodate the delta file.
3. Number of concurrent destinations configured on the backup set:
When generating incremental or differential delta files, each individual concurrent backup
destination will require its own individual delta file. Therefore the disk space required for the drive
where your temporary directory is located will increase with each additional concurrent backup
destination.
Database backup sets which uses the spooling method require additional free disk space than backup
sets which utilize Microsoft Volume Shadow Copy Service (VSS) to obtain a consistent snapshot.
You can use the following formula to calculate the free space required for the temporary directory
depending on the backup set type.
1. For backup sets with spooling
Example:
Backup of 1TB MS SQL Server using ODBC mode with default delta ratio setting of 50% will require up
to 1.5TB of free space on the temporary directory location.
Total File Size Spooled + [(Total File Size x Delta Ratio) x number of concurrent backup destinations]
= minimum Free Space Required
*
Both MS Windows System Backup and MS Windows System State the image can be spooled to a separate partition to the Ahsay
temporary directory.
Backup Set Type
MySQL Database Server
Oracle Database
Lotus Domino
MS SQL Server ODBC mode
MS Windows System Backup *
MS Windows System State *
Operating System
Windows /Linux/ Mac OS X
Linux
Linux
Windows
Windows
Windows
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3. Is there a quick way to calculate the minimum free space required?
Database Size
1TB
1TB
1TB
1TB
Delta Ratio 50%
500GB
500GB
500GB
500GB
Concurrent Destinations
1
2
3
4
Free Space Required
1.5TB
2TB
2.5TB
3TB
2. Backup set without spooling
Example:
Backup of 1TB Hyper-V guest with default delta ratio setting of 50% will require up to 500GB of free
space on the temporary directory location.
(Total File Size x Delta Ratio) x number of concurrent backup destinations
= minimum Free Space Required
†
A VMware ESXi/vCenter backup using VDDK mode, the incremental/differential delta files are directly generated by VMware
host itself and therefore the temporary directory is not used for this purpose.
Caution:
The calculations are based on the current database size, they do not take into account database growth over time. It is
recommended for fast growing databases the minimum free space required should be reviewed on regular basis to avoid
potential backup problems.
Backup Set Type
File
MS SQL Server VSS mode
MS Exchange Database
MS Hyper-V
Office 365 Exchange mail
Cloud File
VMware (Non-VDDK)
VMware (VDDK) †
Operating System
Windows /Linux/ Mac OS X
Windows
Windows
Windows
Windows / Mac OS X
Windows / Mac OS X
Windows / Mac OS X
Windows
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3. Is there a quick way to calculate the minimum free space required? (Continued)
Database Size
1TB
1TB
1TB
1TB
Delta Ratio 50%
500GB
500GB
500GB
500GB
Concurrent Destinations
1
2
3
4
Free Space Required
500GB
1TB
1.5TB
2TB
The default location is dependent on the O/S platform of the machine where AhsayOBM/AhsayACB is
installed on.
Operating System
Windows
Linux/Unix
Mac OS X
Synology NAS
Temporary folder default location
%USERPROFILE%\temp
/root/temp
/Users/%username%/temp
/root/temp
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4. What are the default settings for temporary directory location?
As large files are copied or saved to the temporary directory as part of a database backup or restore
job, to ensure optimal backup and restore performance the location of the temporary directory should
be on a local drive rather than a network drive.
It is NOT recommended to set the temporary directory on:
5. Where should the temporary directory be located?
The O/S or system drive, if the system drive runs out of disk space this could cause the machine to crash.
The same drive as the database files as this could affect the performance of the production system.
1.
2.
On the AhsayOBM/AhsayACB backup client the temporary directory settings can be found in
[Backup Set] > [%BackupSet_Name%] > [Others]
On AhsayCBS user web console the temporary directory settings can be found in
[Backup / Restore] > [User] > [Backup Set] > [%BackupSet_Name%] > [Others]
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6. Where can I find the temporary directory settings?
AhsayOBM and AhsayACB will automatically remove any temporary files when a backup job has com-
pleted by default ‡. This feature is configured by selecting the “Remove temporary files after backup”
option on the backup set.
In some cases where AhsayOBM/AhsayACB is unexpectedly terminated, i.e. the process is killed in
Windows Task Manager or AhsayOBM /AhsayACB crashes during a backup job, before it has had an
opportunity to delete the temporary files then it is recommend to manually delete the files in the
temporary folder.
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7. Do I have to manually delete these files in on the temporary folder drive in order to
ensure there is sufficient free space?
‡ This setting is not available for ShadowProtect Backup Sets
1. Anti-virus software
If the machine has anti-virus software installed please make sure the temporary directory is excluded.
As some anti-virus software may lock or quarantine files created by AhsayOBM/AhsayACB such as
incremental/differential delta files and most importantly the backup index files, causing backup or
restore errors.
2. Exclude the temporary folder from backup source
AhsayOBM/AhsayACB may local its own index files as part of the backup job if these files are included in
the backup source. So make sure the temporary folder is excluded from the backup source.
8. Are there any other factors to take into account?
