36135: Acronis Backup & Recovery 11.5: Acronis Storage Node Operation fails with "The requested operation could not be completed due to a file system limitation "

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Last update: 13-07-2017

When using Acronis Storage Node and deduplication on NTFS filesystem an error occur due filesystem limitation. To fix the issue, reduce the fragmentation by copy forth and back the deduplication storage (datastore) unified_data.ds.0/1.

This article applies to:

  • Acronis Backup & Recovery 11.5 (Advanced Editions)
  • Acronis Backup & Recovery 11 (Advanced Editions)

Symptoms

You are using deduplication feature for your backups and get this error in logs:

The requested operation could not be completed due to a file system limitation

Cause

The used NTFS filesystem has some internal limitations. The important limitation here is the number of fragments for a single file. In this case the datastore file could become large enough and get to much fragments.

Solution

In Acronis Backup & Recovery 11 (Build 17318 or earlier) use one of the following workarounds: 

  1. Copy forth and back the datastore files:
    1. Go to Start -> Run -> services.msc -> and stop Acronis Storage Node service;
    2. Search for this files: unified_data.ds.0 and unified_data.ds.1 and copy them to another place;
    3. If copy has been finished, copy them back to the original destination;
    4. Go to Start -> Run -> services.msc -> and start Acronis Storage Node service;
  2. Backup and restore the datastore files:
    1. Go to Start -> Run -> services.msc -> and stop Acronis Storage Node service;
    2. Perform image backup of volume;
    3. Perform image restore of volume;
    4. Go to Start -> Run -> services.msc -> and start Acronis Storage Node service;

In Acronis Backup & Recovery 11 (Build 17437 or later) and Acronis Backup & Recovery 11.5 use this solution:

Starting from this builds Acronis has implemented pre allocation ability, so the data store files increased with large portions of data, so it has less fragments. The default pre allocation size is 512 MB. For large data store size (e.g. 11 TB) this is not enough. You need to adjust the pre allocation size manually according to the data size planned to be stored in the vault.

To set up pre allocation size follow these steps:

  1.  Go to Start -> Run -> services.msc -> and stop Acronis Storage Node service;
  2. Go to Start -> Run -> regedit.exe to open Windows registry editor and navigate to this key:
     
    HKEY_LOCAL_MACHINE\SOFTWARE\Acronis\ASN\Configuration\StorageNode\PreallocatedDatastoreIncrementSize
     
  3. Change the default value (is 512 in megabytes). If you plan having more than 10 Tb of unique data size it's recommended to set PreallocatedDatastoreIncrementSize to 1024;
  4. Go to Start -> Run -> services.msc -> and start Acronis Storage Node service;

More information

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