APC RAID Subsystem SCSI-SATA II User Manual download pdf (Page 129)

SAS / SATA II NAS System

User’s Manual

129

[Setting]

 Port to Bind - A TCP port to bind locally and is used to connect to the remote node.

Default is 7788.

NOTE: User cannot use ports that already have been used.

Available ports are from 7788 to 77xx.

 Connection Type: proNAS supports two types of data replication protocols:

 Sync - Synchronous. The system will acknowledge the transaction as completed

after the data is written to the disk of destination proNAS. It is recommended to

use this mode. In most cases, this connection type preserves transaction

semantics. Write IO is reported as completed if it has reached the remote disk.

 Async (for high latency network) - Asynchronous. The system will acknowledge

the transaction as completed after the data is written to buffer. It provides faster

transmission and is suitable for busy network. Write IO is reported as completed

if it has reached the local TCP send buffer.

 Max Sync Rate – This sets the limit of the bandwidth that will be used by the

synchronization process. Default is 30MB/sec. Minimum value is 4MB/sec and

maximum value is 680 MB/sec – for high latency network environment (e.g. bonding

on Gigabit Ethernet).

 Send buffer size (K) - It is the size of the TCP socket send buffer. You can specify

smaller or larger values. Larger values are appropriate for reasonable write

throughput with asynchronous protocol over high latency networks. Default is 512K

and maximum is 1024K.

 Time out (sec) - It is the value to wait for connection timeout if the remote node is

degraded. If the remote node fails to send the response packet within the specified

timeout time, the remote node will be considered dead and the TCP/IP connection is

abandoned. The default is 6 sec. Minimum is 1 sec and maximum is 60 sec.

 When Lost Connection: When the replication connection is lost, the replication

program can either go stand-alone or will try to reconnect.

 Reconnect: The replication program will attempt to reconnect. (Default)

 Stand-alone: The replication program will not attempt to reconnect and will go

on stand-alone state. All IO request are only passed locally and no replication.

NOTE: Before replication will be successfully created, a 4GB logical

volume will be created on each node. This will serve as the

metadata device for the replicated volume. This volume is not

mounted and will not be seen on the proNAS GUI. Please be sure

to have an extra 4GB space on either side of your NAS nodes.

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APC RAID Subsystem SCSI-SATA II User Manual Page 129