Supported external system path mode for external volumes

Single or Multi path mode displays in Device Manager - Storage Navigator for external volumes on the External Path Group window. Path modes are based on the external storage system and cannot be changed.

In ALUA mode, the storage system uses all paths that are defined. The storage system performs I/O operations for external volumes through load balancing with the use of several paths (round-robin control). The storage system does not use external paths connected to ports that are in Passive status.

Load Balance Mode

When the path mode of an external volume is Multi or ALUA, you can select an I/O mode for the external storage system.

Depends on the selected external volume(s): If Enable is set for ALUA Settable on the external volume, Normal Round-robin is set for Load Balance Mode automatically. If Disable is set for ALUA Settable, Disable is set for Load Balance Mode automatically.

Normal Round-robin: Normal multi-path I/O control system. This distributes I/O to several paths on which I/O operation is enabled for the external storage system. Specify this if Extended Round-robin might lower I/O performance. This mode is recommended when the number of sequential I/O operations is small.

Extended Round-robin: Extended multi-path I/O control system. I/O is distributed to several paths on which I/O operation is enabled for the external storage system. For sequential I/O, the external volume is divided into sections at regular intervals. In this case, the same path is used for I/O within the same section which reduces the frequency of I/O distribution. You can improve the read speed by using the cache function of the external storage system for sequential I/O operations. This mode is recommended when the number of sequential I/O operations is large.

Disable: I/O operation is performed with only one path that is normal and has the highest priority. The same operation applies as that for Single path mode. When Disable is set for Load Balance Mode, load distribution is not performed. This mode is not recommended.

Depending on the external storage type and system configuration, performance might not be improved when Extended Round-robin is set. In that case, Normal Round-robin is recommended.

The following table shows the path mode for many of the supported external storage systems. The table also shows the abbreviation used in Device Manager - Storage Navigator. If your system is not shown below, refer to http://www.hds.com/products/storage-systems/specifications/supported-external-storage.html.


Storage System	Reference
Virtual Storage Platform G200, G400, G600, G800	Path Mode: Multi Displays as VSP Gx00
Virtual Storage Platform G1000	Path Mode: Multi Displays as Virtual Storage Platform G1000
Unified Storage VM	Path Mode: Multi Displays as HUS VM
Virtual Storage Platform	Path Mode: Multi Displays as VSP
Hitachi Universal Storage Platform V	Path Mode: Multi Displays as USP V
Hitachi Universal Storage Platform VM	Path Mode: Multi Displays as USP VM
TagmaStore® Universal Storage Platform	Path Mode: Multi Displays as USP
TagmaStore® Universal Storage Platform	Path Mode: Multi Displays as NSC
Hitachi Unified Storage	Path Mode: Multi Displays as HUS
Hitachi Adaptable Modular Storage	Path Mode: - Multi: AMS2500, AMS2300, AMS2100, or AMS2010 - Single: AMS1000, AMS500, or AMS200 Displays as AMS
Hitachi Workgroup Modular Storage	Path Mode: Single Displays as WMS
Hitachi Simple Modular Storage	Path Mode: Multi Displays as SMS
Lightning 9900 V Series	Path Mode: Multi Displays as 9970V and 9980V
Lightning 9900 Series	Path Mode: Multi Displays as: - Lightning 9960: 0400 - Lightning 9910: 0401
Hitachi Thunder 9500V series	Path Mode: Single Displays as 9500V
Hitachi SANRISE Universal Storage Platform	Path Mode: Multi Displays as USP
Hitachi SANRISE Network Storage Controller	Path Mode: Multi Displays as NSC
Hitachi SANRISE 9900V series	Path Mode: Multi Displays as 9970V and 9980V
Hitachi SANRISE 9500V series	Path Mode: Single Displays as 9500V
Hitachi SANRISE 2000 series	Path Mode: Multi Displays as: - SANRISE 2800: 0400 - SANRISE 2200: 0401
HP Virtual Storage Platform VX7	Path Mode: Multi Displays as XP7
HP Virtual Storage Platform VP9500	Path Mode: Multi Displays as P9500
A/H-6593	Path Mode: Multi Displays as 300
HP H24000	Path Mode: Multi Displays as 24000
HP H20000	Path Mode: Multi Displays as 20000
HP SANRISE H12000	Path Mode: Multi Displays as 12000
HP SANRISE H10000	Path Mode: Multi Displays as 10000
HP SANRISE H1024/ H128	Path Mode: Multi Displays as 1024 and 128
HP SANRISE H512/H48	Path Mode: Multi Displays as 512 and 48
HP SANRISE H256	Path Mode: Multi Displays as 256
HP XP7	Path Mode: Multi Displays as XP7
HP StorageWorks P9500	Path Mode: Multi Displays as P9500
HP XP24000	Path Mode: Multi Displays as 24000
HP XP20000	Path Mode: Multi Displays as 20000
HP XP12000	Path Mode: Multi Displays as 12000
HP XP10000	Path Mode: Multi Displays as 10000
HP XP1024/XP128	Path Mode: Multi Displays as 1024 and 128
HP XP512/XP48	Path Mode: Multi Displays as 512 and 48
HP XP256	Path Mode: Multi Displays as 256
HP StorageWorks Enterprise Virtual Array 3000/4000/5000/600 0/8000	Path Mode: Single Displays as EVA
SVS200	Path Mode: Multi Displays as SVS200