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Ahsay Cloud Backup Suite v8
Tips On How To Setup The Temporary
Directory For Your Backup Set
Ahsay Systems Corporation
Limited
7 April 2021
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Revision History
Date
Descriptions
Type of modification
7 April 2021
Updated for v8
New/Modifications
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Summary
The setup of the temporary directory is often overlooked and customers typically tend to use
the default setting which is fine for simple file or cloud file backup sets. However, 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 affect the overall
performance.
Some common questions regarding the temporary directory:
How does AhsayOBM/AhsayACB use the temporary directory?
What factors determine the disk space usage or free space required for the temporary
directory?
Is there a quick way to calculate the maximum free space required?
What are the default settings for temporary directory location?
Where should the temporary directory be located?
Where can I find the temporary directory settings?
Do I have to delete the files in the temporary directory in order to ensure there is
sufficient free space?
Are there any other factors to take into account?
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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:
Backup set index files, an updated set of index files is generated after each backup.
The index files are synchronized to each individual backup destination at the end of
each backup job.
File list.
Incremental/differential delta files generated during backups.
For some backup sets, e.g. VM 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 incremental/differential delta files as part of the restore process.
What factors determine the disk space usage or free space
required for the temporary directory?
The following factors need to be taken into account when determining the free space required
for the temporary directory drive or partition:
i. Backup set type
For database backup sets; MS SQL Server in ODBC mode or Lotus
Domino/Oracle/MySQL/MariaDB 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).
ii. In-file delta - Delta ratio setting
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 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.
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iii. Number of destinations configured on the backup set:
When generating incremental or differential delta files, each individual 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 backup destination.
Is there a quick way to calculate the maximum free space
required?
Database backup sets which use the spooling method requires 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.
For Backup Sets with spooling
Backup Set Type
Operating System
MySQL Database Server
Windows / Linux / FreeBSD / macOS
MariaDB Database
Windows / Linux / FreeBSD
Oracle Database
Windows / Linux
Lotus Domino
Linux
MS SQL Server ODBC mode
Windows
MS Windows System Backup
*
Windows
MS Windows System State
*
Windows
* Both MS Windows System Backup
and MS Windows System State the image can be spooled to a
separate partition to the Ahsay temporary directory.
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Total File Size Spooled + [(Total File Size * Delta Ratio) * number of backup
destinations] = Maximum Free Space Required
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.
Database Size
Delta Ratio 50%
Backup
Destinations
Free Space
Required
1TB
500GB
1
1.5TB
1TB
500GB
2
2TB
1TB
500GB
3
2.5GB
1TB
500GB
4
3TB
Backup Set without spooling
Backup Set Type
Operating System
File
Windows / Linux / FreeBSD / macOS
MS SQL Server VSS mode
Windows
MS Exchange Database
Windows
MS Hyper-V
Windows
Microsoft Office 365
Windows / macOS
Cloud File
Windows / macOS
VMware (VDDK)*
Windows
*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.
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.
VM Size
Delta Ratio 50%
Backup
Destinations
Free Space
Required
1TB
500GB
1
500GB
1TB
500GB
2
1TB
1TB
500GB
3
1.5GB
1TB
500GB
4
2TB
(Total File Size * Delta Ratio) * number of backup destinations = Maximum Free
Space Required
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 that the
maximum free space required should be reviewed on a regular basis to avoid potential
backup problems.
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What are the default settings for temporary directory
location?
The default location is dependent on the O/S platform of the machine where
AhsayOBM/AhsayACB is installed.
Operating System
Temporary folder default location
Windows
%USERPROFILE%\temp
Linux / FreeBSD
/root/temp
macOS
/Users/%username%/temp
Synology DSM
/root/temp
QNAP QTS
/root/temp
Where should the temporary directory be located?
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:
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.
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Where Can I Find the Temporary Directory Settings?
On the AhsayOBM/AhsayACB backup client GUI 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, Groups & Policies] > [Backup User] > [%Backup_User_Name%] > [Backup
Set] > [%BackupSet_Name%] > [Others].
For AhsayOBM on Linux / FreeBSD CLI environment, AhsayCBS user web console should be
used to obtain the temporary directory settings.
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Do I have to delete the files in the temporary directory in order
to ensure there is sufficient free space?
AhsayOBM and AhsayACB will automatically remove any temporary files when a backup job
has completed by default*. This feature can be configured by selecting the “Remove
temporary files after backup” option on the backup set.
*This setting is not available for ShadowProtect Backup Sets
NOTE
In some cases where AhsayOBM/AhsayACB is unexpectedly terminated, e.g. the process is killed
in Windows Task Manager or AhsayOBM/AhsayACB crashes during a backup job, before it had an
opportunity to delete the temporary files then it is recommended to manually delete the files in the
temporary folder.
Are there any other factors to take into account?
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 for example incremental /differential delta files and most
importantly the backup set index files causing backup or restore errors.
2. Exclude the Temporary Folder From Backup Source
AhsayOBM/AhsayACB may lock 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.
