SMSDOM Best Practices: temporary space usage

Products

• Mail Security for Domino

Issue/Introduction

You're using Symantec Mail Security for Domino and need to understand what recommendations exist for the product's handling of disk space reserved for the termporary processing of files and messages.

Cause

Symantec Mail Security for Domino uses the temporary space (either configured in the product's settings or default system variable) to decompose files and messages. The amount of disk space used required depends on the average document and mail flow and the average size of each file or message.

Resolution

Please consider the best practices below to make sure Symantec Mail Security for Domino will be able to use its temporary space properly.

System recommendations:

• It's recommended that you always specify a folder for temporary processing of files by Symantec Mail Security for Domino. Please refer to the product's Implementation Guide for more information.
• In case you're using Domino Partitions, it's recommended that you specify a different temporary folder for each partition.
• Also, you should make sure to clean this folder before each Symantec Mail Security for Domino service startup; in particular, make sure to remove all files and directories starting with "SMS" and "csapi".

How to calculate the disk space for Symantec Mail Security's temporary processing:

If the SMSDOM settings include the followings:

• maximum extracted attachment size as "ASize" (MB)
• number of SMSDOM threads as "TNum"
• maximum decomposition file system size as "DSize" (MB)

Locations of ASize and DSize values in the Settings database (sav.nsf) GUI are :

ASize : Configuration -> Scan Error -> Container Limits -> Attachment where the cumulative size of all extracted files exceeds x MBs in size (200MB by default). This setting sets the maximum space for decomposer to use.

DSize: Threat/Security Risk -> Basics -> Maximum memory to use per thread for extracting attachments (Files over this size will be extracted on disk): 20000 Kilobytes (20MB by default).

...Then the temporary folder specified in Symantec Mail Security for Domino settings should have disk space according to the formula:

(ASize * TNum + DSize) = 75% of the disk space

 

Example: if ASize=100MB and TNum=64 threads and DSize=20MB, the required space would be (100*64+20)/0.75 = 8560MB.

• If N domino partitions share this temporary folder than size should be multiplied by N, i.e. (100*64+20)*3/0.75 = 25680MB.

• In Symantec Mail Security for Domino 8.0.1, leverage in-memory scanning by increasing process default heap memory in your system settings and then you can set SAVBufferSize=1048576 to a suitable value.
  • E.g. as a rule of thumb, process default heap size can roughly be No.of nntask threads * SAVBufferSize + 50 MB (which includes Decomposer's in-memory file system + other native allocations done in smsdom e.g. in ACF etc.).

• Reconsider some related scan error settings e.g. specifying apt maximum file size and max total extracted size etc. This will prevent smsdom from scanning such large files.

Note: Symantec Mail Security for Domino creates temp files while at the time of scan and they are (in normal circumstances) removed automatically after the scan completes.