Ahsay Know Issue: Corrupt GZIP trailer (failure to restore file with incremental / differential In-file delta) (3224)

Ahsay Know Issue:

Corrupt GZIP trailer (failure to restore file with incremental / differential In-file delta) (3224)

Product Version:
AhsayACB / AhsayOBM: Pre-6.27.0.0
OS: All platforms

Problem Description:
When performing a restore / decrypt for a backup set of any type, the following error message is received in the client log:

[YYYY/MM/DD hh:mm:ss] [erro] [Restorer.run] Path=\directory\file Throwable=[java.io.IOException] [ReadAheadInputStream.BlockLoader.run] Throwable=[EncryptedRafDecryptInputStream.postLoadBlock] Unexpected IOException, caused by [java.io.IOException] [EncryptedRafDecryptInputStream.postLoadBlock] Unexpected IOException, caused by [java.io.IOException] Corrupt GZIP trailer

Cause:
This issue can occurs if the In-file delta file generated in the temp folder of the original backup job was corrupted (e.g. hardware issue on the AhsayOBM / ACB client computer) before it was uploaded to the backup server.

Important:
This type of corruption cannot be detected by a single backup set rebuild with verify checksum option enabled, or the bi-weekly Cyclic Redundancy Check (CRC) checking system routine job.

Stages of a delta generation process during a backup job are outlined as follow:

Checksum of source file is downloaded from the AhsayOBS server (if available).
The In-file delta file is generated, encrypted and saved in the temporary folder configured.
A new checksum file is generated from the encrypted delta file and uploaded to the backup server.
The In-file delta file is also uploaded to the backup server at the same time.

If the incremental / differential delta file is generated on a faulty volume on the AhsayOBM / ACB client computer (during Step 2), the corrupted delta file cannot be merged with the full file (for a restore / decrypt / delta merge).

Resolution:
Corrupted delta file cannot be merged with the full file, try restoring a previous snapshot of the file to see if the problem persist.

To prevent the issue from occurring in the future, patch the AhsayOBM / ACB client application to version 6.27.0.0.  The instruction can be found by Clicking Here.

Enhancement has been made to the client application to validate the generated delta file in the temp folder, to ensure that the delta file is not corrupted before it is uploaded.  If the delta file is corrupted, the following error message would be displayed, and the file will not be uploaded to the AhsayOBS server:

[YYYY/MM/DD hh:mm:ss] [erro] [Error][Updated File] File="\directory\file" Error="[com.ahsay.obc.core.bset.file.x] "\directory\file" delta file checksum incorrect (Expected=expected_size Actual=actual_size)"