EonStor DS Firmware User Manual
Trunking and Grouping Trunking and Grouping functions are available only for iSCSI host models.
What is Trunking /
Trunking provide network access to many clients by sharing a set of lines
Grouping?
instead of providing them individually. Trunking binds multiple physical interfaces so they are treated as one, and is accomplished in the TCP/IP stack. Grouping (MC/S) combines multiple host ports into a logical initiator-target session. Grouping can improve the throughput and transfer efficiency over a TCP session and saves the effort of mapping a logical drive to multiple host channel IDs on multiple host ports. Grouping provides sophisticated error handling such that a failed link is recovered quickly by other good connections in the same session. Grouping is part of the iSCSI protocol that is implemented underneath SCSI and on top of TCP/IP.
Grouping Example
The below drawings show 4 channels configured into an MC/S group.
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Trunking into
All ports can be trunked into a single or multiple IPs. Four iSCSI ports can have
Multiple IP
two IPs each by trunking two physical ports. Trunked ports combinations can be
Addresses
2, 3, 4, 5, 6.
Host initiators determine how I/O traffic is distributed through multiple target portals. Theoretically, I/Os are evenly distributed across physical paths.
Limitations: Trunking
Number of Host Ports in a Trunk Up to four
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Combining Trunking and Grouping You cannot configure grouped channels into trunks but you can configure trunked ports into groups. This restriction is due to the order in protocol layer implementation.
You must configure trunking before grouping. If a grouping exists before you configure trunking, you must delete the grouping first.
Channels: You Cannot Trunk Channels that have LUN mapping on them. Channels that are already trunked. Channels that are already included in groups.
Networking Aggregation interfaces must be connected in the same network, preferably the same Ethernet switch, to minimize physically isolating paths.
The surrounding devices such as switches and HBA cards must also be trunking- or grouping-compatible.
Events If a trunk configuration is not valid, the firmware will report a trunk failure event.
Limitations: Grouping
Combining Trunking and Grouping You cannot configure grouped channels into trunks but you can configure trunked ports into groups. This restriction is due to the order in protocol layer implementation.
You must configure trunking before grouping. If a grouping exists before you configure trunking, you must delete the grouping first.
Multiple RAID Systems Host ports on different RAID controllers (a redundant-controller system) will not be grouped together. Namely, in the event of a single controller failure, the IPs do not failover to the surviving controller.
Networking
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Aggregation interfaces must be connected in the same network, preferably the same Ethernet switch, to minimize physically isolating paths.
The surrounding devices such as switches and HBA cards must also be trunking- or grouping-compatible.
Parameters after Trunking
After ports are trunked, they will collectively have:
One channel ID One IP address in one subnet One host LUN Mapping
Configuration Steps
Configure trunking in the following order: 1. Configure the switch. 2. Trunk host ports or group them. (If you trunk host ports, grouping will be automatically done).
Configuring the Switch You should configure switch setting before changing subsystem setting.
Supported
Make sure you have appropriate configurations both on your iSCSI system and
Configurations
Ethernet switches. Otherwise, networking failures will occur.
Example
This example shows the locations of configurations for 3COM Baseline Switch 2924. Your switch’s settings will be different but should follow similar paths.
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Configuration menu: Port Link Aggregation Aggregation group ID
Port selection menu: LACP Select Port
Trunking Host Ports After trunking, channels will be automatically configured into groups.
Available in
LCD
Terminal
RAIDWatch
LCD Interface
Go to: View and Edit Config Parms Communication Parameters Trunk Group Setting
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Communication Parameters
Terminal Interface
ENT
View and Edit Configuration Parameters Communication Parameters View and Edit Trunk Group Setting
1. Select Create Trunk Group.
2. Select the channels to be trunked.
3. The summary appears. Select Yes.
4. Trunk configuration will appear.
RAIDWatch
Trunk Group Setting
Go to: Config Trunk Group
Interface
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Configuring Trunking Available in
LCD
Terminal
RAIDWatch
LCD Interface
View and Edit Config Parms Communication Parameters Trunk Group Setting
Communication Parameters
Terminal Interface
ENT
Trunk Group Setting
View and Edit Configuration Parameters Communication Parameters View and Edit Trunk Group Setting
1. Select the trunk configuration.
2. You may delete the trunk group or add/delete member hosts.
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You cannot remove a member if you have mapped the trunk ports.
RAIDWatch
Config Trunk Group
Interface
Grouping Channels You do not have to group channels if you have already trunked host ports.
Available in
LCD
Terminal
RAIDWatch
LCD Interface
View and Edit Channels (Host Channel) Add to Group
Add to Group
Terminal Interface
View and Edit Channels (Host Channel) Add to Group
RAIDWatch
Channel Channel List Group
Interface
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LUN Presentation
With logical grouping, a logical drive mapped to a channel group will appear as
with Grouping
one device on multiple data paths (below left figure). This is very similar to using multi-pathing drivers. Without grouping, a storage volume will appear as two devices on two data paths (below right figure).
Grouping Applications LUN Presentation
With logical grouping, a logical drive mapped to a channel group will appear as
with Grouping
one device on multiple data paths (below left figure). This is very similar to using multi-pathing drivers. Without grouping, a storage volume will appear as two devices on two data paths (below right figure).
Dividing Channels
For dual-controller subsystems, you can only see the channel settings for a
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single controller, yet actually they are automatically applied to the partner controller. If you configure “channel groups,” you actually create juxtaposed groups on partner controllers. One volume mapped to both an AID and a BID will appear as two devices on the A links and on the B links. You will then need the EonPath multi-pathing driver to manage the fault-tolerant paths.
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