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Data access is slower after starting Volume Replication task.

Article ID: 2483
Last updated: 05 Aug, 2015

Volume replication is a synchronous process. While read is independent of link between two nodes, write operation is considered done only when it is confirmed on both nodes. It is very important, than both machines have similar capabilities in terms of storage speed, and fast enough network bandwidth between them.

You may test network bandwidth with the System control and network test small update file, you may ask our support team to support you with the small update file ( 70001-DSS-V7_SYSCTL_AND_NETWORK_TEST) or the SU # 70001.

Network test can be run from DSS Console -> Ctrl+alt+T -> Addons -> Tcp network test.
One node must be set to server mode, and on other one you provide IP address to start the test.
Please note that network bandwidth can be lower than f.e. expected from 1GbE controller because of other network elements. Usually it is advised to use direct connection between servers.

If you have already confirmed that network is performable enough volume replication can be tuned by following 'Tuning recommendations':

(Deprecated since DSS V7 up 12)


http://kb.open-e.com/Tuning-recommendations-for-volume-replication-over-1GbE_1603.html


Storage performance test can be done from DSS Console -> Ctrl+alt+W -> System benchmank -> Disk performance test. Read test is safe for data, but write test will overwrite anything on the drive. It is important to do write test only on clear units. Please note that read and write performance is usually different and you should not look only on read results when calculating the capabilities of the system.

Without fast enough hardware on both nodes and link between them volume replication can limit write speed possibilities of source node.

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Article ID: 2483
Last updated: 05 Aug, 2015
Revision: 1
Views: 1857
Posted: 13 Aug, 2013 by Lupa P.
Updated: 05 Aug, 2015 by Lupa P.
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