45424: Acronis Backup Advanced: Troubleshooting Slow Deduplication

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    This article provides instructions on how to troubleshoot and resolve issues with slow backup to a deduplicating vault.

    Follow these steps to troubleshoot slow deduplication:

    1. Get familiar with technology of deduplication in the About part.
    2. Follow to Troubleshooting part to troubleshoot and resolve the issue.

    About

    Deduplication is the process of minimizing storage space taken by the data by detecting data repetition and storing the identical data only once.

    Acronis Backup will deduplicate backups saved to a managed vault if you enable deduplication during the vault creation. When creating a vault on a storage node, you specify paths to the vault folder and the vault database. The vault folder stores backup files reduced as a result of deduplication and one or two large files (datastores) that contain data items unique to the vault. The vault database stores the links (hash values) that are necessary to ‘assemble’ the deduplicated data.

    Acronis Backup performs deduplication in one or two steps: optional deduplication at source (performed on a managed machine during backup, data blocks whose duplicates are already present in the vault are not transferred during backup) and dedulication at target also called “indexing” (performed in the vault after a backup is completed, the storage node analyses the vault's contents and deduplicates data in the vault). Deduplication at source can be turned on and off in the settings of the backup plan.

    Deduplication at source reduces network and ASN resources load, but increases Agent machine’s CPU and RAM load. Backup takes more time with enabled deduplication at source.

    Deduplication at target does not reduce network, but uses Storage Node resources only and does not affect performance of Agent machine.

    The compacting operation is part or the deduplication process. It removes the data items that become unnecessary after some of the backups have been deleted. Compacting creates a ‘clone’ of the datastore, but it does not copy the entire datastore at once. The software checks every data item in the datastore. If there is a link to the item from an existing archive, the item is moved to the new datastore. At the end of the operation, the old datastore contains only the unnecessary items and it is safely deleted.

    Troubleshooting

    Follow step-by-step instructions below to troubleshoot the issue. Complete prerequisites step before proceeding to error troubleshooting step.

    1. Prerequisites

     Complete all steps before proceeding to error troubleshooting step.

    1.1 Storage Node requirements

     - Prepare a dedicated machine for Acronis Storage Node hosting deduplication vaults.

    - Server Operating System is preferred.

    - 64-bit system is the minimal requirerment. Calculate RAM requirements using this formula: REQUIRED_RAM_FOR_BEST_PERFORMANCE = DEDUP_DB_SIZE / 0.8;

    - Machine meets hardware requirements: see ASN Hardware Configuration Guide

    1.2 Deduplicating vault requirements

    - Vault data and vault deduplication database folders should reside on different physical devices to avoid performance degradation.

    - The deduplication database does not reside on the C:\ volume and not on the same disk as the operating system. The reason is that the operating system has a lot of hard disk reads/writes which significantly slow down the deduplication performance.

    - If vault data is stored on a NAS, make network connection as fast as possible. Gigabit Ethernet is recommended.

    - If vault data is stored on locally attached HDDs, use the fastest controllers and high RPM drives.

    - Having one deduplicating vault per Acronis Storage Node is the best practice.

    If all steps above have been executed and issue still persists, go to error troubleshooting step.

    2. Error troubleshooting

    Complete all steps before proceeding to collect information step.

    2.1 Check CPU usage

    Reproduce the issue and check CPU usage:

    On Windows Server 2008/2012 with Resource Monitor:

    1 - Click Start, click in the Start Search box, type resource monitor, and press Enter.

    2 – Choose StorageServer.exe Process:

    3 - Observe performance. If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Check other parameters and proceed to step 2.4 to calculate hardware for your ASN machine.

     

    On Windows Server 2003 with Performance Monitor:

    1 - Click Start, click in the Start Search box, type perfmon, and press Enter.

    2 - In the navigation tree, expand Monitoring Tools, and then click Performance Monitor.

    3 – Press on x to clear current counters.

    4 – Click on + to add the following counters:

    Processor: % Processor Time

    5 - Observe performance:

    If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Check other parameters and proceed to step 2.4 to calculate hardware for your ASN machine.

    2.2 Check RAM usage

    Reproduce the issue and check RAM usage:

    On Windows Server 2008/2012 with Resource Monitor:

    1 - Click Start, click in the Start Search box, type resource monitor, and press Enter.

    2 – Choose StorageServer.exe Process.

    3 - Observe performance. If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Check other parameters and proceed to step 2.4 to calculate hardware for your ASN machine.

     

    On Windows Server 2003 with Performance Monitor:

    1 - Click Start, click in the Start Search box, type perfmon, and press Enter.

    2 - In the navigation tree, expand Monitoring Tools, and then click Performance Monitor.

    3 – Press on x to clear current counters.

    4 – Click on + to add the following counters:

    Memory: Free & Zero Page List Bytes

    5 - Observe performance. If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Check other parameters and proceed to step 2.4 to calculate hardware for your ASN machine.

    2.3 Drive Read/Write Speed

    Reproduce the issue and check read/write speed of you drive:

    On Windows Server 2008/2012 with Resource Monitor:

    1 - Click Start, click in the Start Search box, type resource monitor, and press Enter.

    2 – Choose StorageServer.exe Process:

    3 - Observe performance. If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Proceed to step 2.4 to calculate hardware for your ASN machine.

     

    On Windows Server 2003 with Performance Monitor:

    1 - Click Start, click in the Start Search box, type perfmon, and press Enter.

    2 - In the navigation tree, expand Monitoring Tools, and then click Performance Monitor.

    3 – Press on x to clear current counters.

    4 – Click on + to add the following counters:

    PhysicalDisk: Disk Read Bytes/sec, Disk Write Bytes/sec

    5 - Observe performance. If this parameter reaches its maximum peak and stays at/close to this value during backup, this is the bottle neck of your hardware resources. Proceed to step 2.4 to calculate hardware for your ASN machine.

    2.4 Calculate Hardware Requirements

    Calculate hardware requirements for your environment with ASN Hardware Configuration Wizard

    If all steps above have been executed and the ASN machine meets hardware requierements or hardware is not exhausted according to Resource Monitor/Performance Monitor, go to collect information step.

    3. Collect information

    Collect following information and contact Acronis Customer Central.

    3.1 Backup speed

     Note speed during a backup to a deduplicating vault. Create a test centralized managed vault with no dedup on the same disk, and note speed during the backup to this vault too.

    3.2 Expected Backup Speed

    Note what deduplication speed is expected by the Customer.

    3.3 Environment Description

    Detailed description of environment and deduplicating settings:

    - Size of deduplicating vault.

    - Size of the deduplication database.

    - What is being backed up (physical or virtual machines or both types, file-level or disk-level backups)?

    - How many deduplicating vaults exist on the Acronis Storage Node that experiences slow speed of deduplication?

    - How many machines are being backed up to each deduplicating vault?

    - Is deduplication at source enabled?

    3.4 Vault Location

    - interface of HDD of the vault (internal, external, esata, scsi, NAS, etc)

    - interface of HDD of the vault database (internal, external, esata, scsi, NAS, etc)

    - LAN speed

    3.5 System Report from the Storage Node machine

    Collect System Report from the Storage Node machine: see instruction for Acronis Backup 11.7/1.5: Generating System Report, if this fails for any reason, you can use this AcronisInfo Utility.

    Or collect with Acronisinfo Utility if ASN is installed on a separate machine: AcronisInfo Utility.

    3.6 System Report from agent machines

    If deduplication is performed at source, collect System Report from 2-3 machines being backed up to the problem vault: see instruction for Acronis Backup 11.7/11.5: Generating System Report, if this fails for any reason, you can use this AcronisInfo Utility.

    3.7 Resource Monitor/Performance Monitor Logs

    Make screenshots of Resource Monitor/Performance Monitor data during problem reproduction.

    3.8 Process Monitor Log and Dump

    If indexing operation hangs, collect Process Monitor Log (see Collecting Process Monitor Log) on the ASN machine and dump of StorageServer.exe (see Creating Process Dumps with ProcDump).

    3.9 Network Tracing Log 

    - Collect network tracing log with WireShark utility if data transfer speed is low and deduplication at source is disabled: see Collecting WireShark Log.

    - Also note transfer speed while copying some files (e.g. 1 GB) from the Agent machine to the ASN machine and to the vault location afterwards

    3.10 Amount of unindexed data 

    - Go to the vault using Window Explorer. Search for "*.LDS". Select all found files. Provide a picture of the search result so Total amount of files and their cumulative size is seen.

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