Host Mode Option settings

Very often the question arises when to set which Host Mode Option. Below is a table that explains the settings you will require when certain OS'es and/or applications are installed. Pay attention to the notes below the table.

 

So what do these HMO settings do? Basically they instruct the microcode to enable or disable certain functionality on LUNs and report those settings in VPD pages back to the host when it queries the target. Depending on these settings the host can take appropriate actions and knows which SCSI commands it can and cannot use towards the array. This is very important with for instance clustering, write(16), write same commands. If these setting are incorrect the host might send incorrect commands or the array might send incorrect status messages which can cause data corruption, performance and availability problems etc. Please take care of these settings and make sure they are appropriate towards your environment.

 

Not all mode setting apply to all systems as well as some might not be available on older microcode. Also some host mode settings should only be set with HDS Techsupport or Hitachi RSD support approval since they might have some hooks into other HMO or System Option Mode settings which should be verified beforehand. These are also not listed below.


Host mode When to select this mode?
Host Mode Settings
00 Standard When registering Red Hat Linux server hosts or IRIX server hosts in the host
group
01 VMware When registering VMware server hosts in the host group
03 HP When registering HP-UX server hosts in the host group
05 OpenVMS When registering OpenVMS server hosts in the host group
07 Tru64 When registering Tru64 server hosts in the host group
09 Solaris When registering Solaris server hosts in the host group
0A NetWare When registering NetWare server hosts in the host group
0C Windows When registering Windows server hosts in the host group
0F AIX When registering AIX server hosts in the host group
21 VMware Extension When registering VMware server hosts in the host group
2C Windows Extension When registering Windows server hosts in the host group
4C UVM When registering another USP V/VM storage system in the host group for mapping by using Universal Volume Manager (Use this mode when you want to map logical volumes in the
USP V/VM storage system on which LUN Manager is installed, to another USP V/VM storage
system on which Universal Volume Manager is installed as the data is transferred with the
same emulation type. The volume data of the emulation type other than OPEN-V cannot be
transferred when the storage system is connected with the host mode other than "4C UVM",
and the message to demand formatting is displayed after the mapping. Please cancel the
message to demand formatting, and set the host mode to "4C UVM" when you want to transfer data.)
   
Option  
2 VERITAS Database Edition/ Advanced Cluster When VERITAS Database Edition/Advanced Cluster for Real Application Clusters or VERITAS Cluster Server 4.0 or later (I/O fencing function) is used
6 TPRLO

When all the following conditions are satisfied:

· The host mode 0C Windows or 2C Windows Extension is used

· The Emulex host bus adapter is used · The mini-port driver is used

· TPRLO=2 is specified for the mini-port driver parameter of the host bus adapter

7 Automatic recognition function of LUN

When all the following conditions are satisfied: ·


The host mode 00 Standard or 09 Solaris is used

· SUN StorEdge SAN Foundation Software Version 4.2 or better is used

· You want to automate recognition of increase and decrease of devices when genuine SUN HBA is connected
12 No display for ghost LUN

When all the following conditions are satisfied:

· The host mode 03 HP is used

· You want to suppress creation of device files for devices to which paths are not defined.

13 SIM report at link failure When the user want to be informed by SIM (service information message) that the number of link failures detected between ports exceeds the threshold
14 HP TruCluster with TrueCopy function

When all the following conditions are satisfied:

· The host mode 07 Tru64 is used

· You want to use TruCluster to set a cluster to each of P-VOL and S-VOL for TrueCopy or Universal Replicator.

15 HACMP

When all the following conditions are satisfied:

· The host mode 0F AIX is used

· HACMP 5.1 Version 5.1.0.4 or later, HACMP4.5 Version 4.5.0.13 or later, or HACMP5.2 or
later is used

22 Veritas Cluster Server

When all the following conditions are satisfied:

· The host mode 0F AIX is used

· Veritas Cluster Server is used

23 REC Command Support When the user want to shorten the recovery time on the host side if
the data transfer failed
33 Set/Report Device Identifier Enable

When all the following conditions are satisfied:

· The host mode 03 HP is used · You want to enable commands to assign a nickname of the
device with HP-UX hosts.

40

This mode is used to control whether UA is returned to the host when a command from the host is received for the LU whose capacity has been expanded.

Mode 40 = ON: When a command from the host is received for the LU whose capacity has been expanded, UA is returned to the host.

Mode 40 = OFF (default): When a command from the host is received for the LU whose capacity has been expanded, UA is not returned to the host.
41 This mode is used to give priority to starting Inquiry/ Report LUN issued from the host where this option is set. During busy operations with lots of reads and writes the MP might become so busy that an inquiry command is processed just a bit too late which in some cases causes a host to loose it's disks because of a timeout.

Mode 41 = ON:
Inquiry/ Report LUN is started by priority.

Mode 41 = OFF (default):
The operation is the same as before.
42 When CHA PCI is accessed from MP, the behavior when the status is busy differs depending on the mode status as follows.

Mode 42 = ON:
The PCI retry is not returned, and the PCI bus is occupied.
Mode 42 = OFF (default):
The PCI retry is returned.

Note:
When IBM Z10 Linux is connected, set this mode to ON. In other cases, set the mode to OFF.
43 When Queue Full occurs, this option is used to return Queue Full to the host.

Mode 43 = ON:
When Queue Full occurs, Queue Full is always returned to the host.
Mode 43 = OFF (default):
When Queue Full occurs with Host Mode HP-UX, Busy is returned to the host.

Note:
Set HMO 43 to ON when HP-UX 11.x or higher is connected.
However, if the setting of queue depth on the host is made based on the configuration guide, the mode setting is not necessary since Queue Full/ Busy will not occur.
 
48 By setting this option to ON, in normal operation, the pair status of S-VOL is not changed to SSWS even when Read commands exceeding the threshold (1,000/6 min) are issued while a specific application is used.

Mode 048 = ON:
The pair status of S-VOL is not changed to SSWS if Read commands exceeding the threshold are issued.

Mode 048 = OFF (default):
The pair status of S-VOL is changed to SSWS if Read commands exceeding the threshold are issued.

Note:
1. Set this option to ON for the host group if the transition of the pair status to SSWS is not desired in the case that an application, which issues Read commands (*1) exceeding the threshold (1,000/6 min) to S-VOL, is used in HAM environment,.
(*1: Currently, the vxdisksetup command of Solaris VxVM serves.)
2. Even when a failure occurs in P-VOL, if this option is set to ON, which means that the pair status of S-VOL is not changed to SSWS (*2), the response time of Read command to the S-VOL whose pair status remains as Pair takes several msecs.
On the other hand, if the option is set to OFF, the response time of Read command to the S-VOL is recovered to be equal to that to P-VOL by judging that an error occurs in the P-VOL when Read commands exceeding the threshold are issued.
(*2: Until the S-VOL receives a Write command, the pair status of S-VOL is not changed to SSWS. )
49 This option can be used to select BB_Credit value.
(HMO#49: Low_bit)

Mode 49 = ON:
The subsystem operates with BB_Credit value of 80 or 255.

Mode 49 = OFF (default):
The subsystem operates with BB_Credit value of 40 or 128.

*HMO#50/HMO#49: BB_Credit value is decided by 2 bits of the two HMO.
00: Existing mode (BB_Credit value = 40) 01: BB_Credit value = 80
10: BB_Credit value = 128 11: BB_Credit value = 255

Note:
1.This option is applied when the two conditions below are met:
- Data frame transfer in long distance connection exceeds the BB_Credit value.
- System option mode 769 is set to OFF (retry operation is enabled at TC/UR path creation).
2. When HMO 49 is set to ON, SSB log of link down is output on MCU (M-DKC).
3. This HMO can work only when the micro-program supporting this function is installed on both MCU (M-DKC) and RCU (R-DKC).
4. The HMO setting is only applied to Initiator-Port. This function is only applicable when the 8US PCB is used on RCU/MCU.
5. If this option is used, Point to Point setting is necessary.
6. When removing the 8US PCB, the operation must be executed after setting the HMO 49 to OFF.
7. If HMO 49 is set to ON while SOM 769 is ON, path creation may fail after automatic port switching.
8. Make sure to set HMO 49 from OFF to ON or from ON to OFF after the pair is suspended or when the load is low.
9. The RCU Target, which is connected with the MCU where this mode is set to ON, cannot be used for UR.
50 This option can be used to select BB_Credit value.
(HMO#50: High_bit)

Mode 50 = ON:
The subsystem operates with BB_Credit value of 128 or 255.

Mode 50 = OFF (default):
The subsystem operates with BB_Credit value of 40 or 80.

*HMO#50/HMO#49: BB_Credit value is decided by 2 bits of the two HMO.
00: Existing mode (BB_Credit value = 40) 01: BB_Credit value = 80
10: BB_Credit value = 128 11: BB_Credit value = 255

Note:
1. This option is applied when the two conditions below are met:
- Data frame transfer in long distance connection exceeds the BB_Credit value.
- System option mode 769 is set to OFF (retry operation is enabled at TC/UR path creation).
2. When HMO 50 is set to ON, SSB log of link down is output on MCU (M-DKC).
3. This HMO can work only when the micro-program supporting this function is installed on both MCU (M-DKC) and RCU (R-DKC).
4. The HMO setting is only applied to Initiator-Port. This function is only applicable when the 8US PCB is used on RCU/MCU.
5. If this option is used, Point to Point setting is necessary.
6. When removing 8US PCB, the operation must be executed after setting the HMO 50 to OFF.
7. If HMO 50 is set to ON while SOM 769 is ON, path creation may fail after automatic port switching.
8. Make sure to set HMO 50 from OFF to ON or from ON to OFF after the pair is suspended or when the load is low.
9. The RCU Target, which is connected with the MCU where this mode is set to ON, cannot be used for UR.
51 This option can be used to select operation condition of TrueCopy.

Mode 51 = ON:
TrueCopy operates in the performance improvement logic.
(When a WRITE command is issued, FCP_CMD/FCP_DATA is continuously issued while XFER_RDY issued from RCU side is prevented.)

Mode 51 = OFF (default):
TrueCopy operates in the existing logic.

Note:
1. This option is applied when write I/O of TrueCopy is executed.
2. When HMO 51 is set to ON, SSB log of link down is output on MCU (M-DKC).
3. This HMO can work only when the micro-program supporting this function is installed on both MCU (M-DKC) and RCU (R-DKC).
4. The HMO setting is only applied to Initiator-Port. This function is only applicable when the 8US PCB is used on RCU/MCU.
5. When removing 8US PCB, the operation must be executed after setting the HMO 51 to OFF.
6. Make sure to set HMO 51 from OFF to ON or from ON to OFF after the pair is suspended or when the load is low.
7. The RCU Target, which is connected with the MCU where this mode is set to ON, cannot be used for UR.
8. This function cannot be used together with the FCSW function, which transfers data to the Target side asynchronously by buffering the data in switch. For example, this function cannot be used together with the Fast Write function of Brocade Switch or the Write Acceleration function of Cisco Switch.

 
54 This mode enables the XCOPY command to be used.

Mode 054 = ON:
The XCOPY command can be used.

Mode 054 = OFF (default):
When the XCOPY command is received, Check Condition is returned as an unsupported command （0x05/0x2000）.

Note:
(1) - The HMO is set to ON only when a VMWare ESX/ESXi 4.1 server using the VAAI (vStorage API for Array Integration) function is connected.
(2) If the HMO is not applied, the VMWare support function, Cloning file blocks, cannot be used.
 
61 This mode is used to increase Reservation Keys from 128 to 2,048.

Mode 61 = ON:
Up to 2,048 Reservation Keys can be allowed per port.

Mode 61 = OFF (default):
128 Reservation Keys can be allowed per port.

Note:
1. HMO 61 is applied when more than 128 Reservation Keys are required in the environment using the Persistent Reserve command.
2. When the option is set to ON, the performance of the Persistent Reserve command and read/write commands may degrade.
3. When the option is switched from ON to OFF, the expanded keys used so far become unavailable.
4. HMO61 setting can be switched from ON to OFF only when SOM864 is ON. To switch OFF from ON, make sure that there is no LU with PGR/Key registered in the target group.
5. If HMO61 is ON, the performance of Persistent Reserve command and that of I/O for Persistent Reserve LU may degrade.
6. If a host group where HMO61 is ON is deleted and a new host group is created, HMO61 goes OFF. However, if any LU with PGR/Key registered exists in the target group, host group deletion ends abnormally. (Current spec)
7. During micro-program version downgrade, if a HMO61-caused error occurs, HMO61 needs to be set to OFF.
8. Switching HMO61 from ON to OFF while the 129th and later reservation keys exist may cause the following adverse effects, which may result in server down.
- Registered Reservation Keys become invalid.
- The above Reservation Keys suddenly become valid when the option is set to ON again.
9. The 129th and later Reservation Keys can be deleted by the following operations.
- Micro-program exchange from an unsupported version to a supported version.
- Forcible reserve cancellation.
10. HMO61 can be set to OFF in accordance with the following procedure.
Procedure1: When neither “PGR” nor “KEY” is displayed on the LUN Status window
(1) Set SOM864 to ON
(2) Set HMO61 to OFF
(3) Set SOM864 to OFF
Procedure2: When either “PGR” or “KEY” is displayed on the LUN Status window
(1) Release the “PGR” or “KEY” from the host.
(2) Confirm that neither “PGR” nor “KEY” is displayed on the LUN Status window
(3) Set SOM864 to ON.
(4) Set HMO61 to OFF
(5) Set SOM864 to OFF.
 

 

 

Notes:

If you register Windows server hosts in a host group, you need to ensure that the host mode of the host group is 0C Windows or 2C Windows Extension. If you are thinking about creating LUSE volumes (i.e., expanded LUs), you should consider setting the host mode 2C Windows Extension to the host group.
If the host mode of a host group is 0C Windows and an LU path is defined between the host group and a logical volume, you cannot combine the logical volume with other logical volumes to form an LUSE volume (i.e., an expanded LU). For detailed information about LUSE, please refer to LUN Expansion User's Guide.


If you register VMware server hosts in a host group, you need to ensure that the host mode of the host group is 01 VMware or 21 VMware Extension. If you are thinking about creating LUSE volumes (i.e., expanded LUs), you should consider setting the host mode 21 VMware Extension to the host group.
If the host mode of a host group is 01 VMware and an LU path is defined between the host group and a logical volume, you cannot combine the logical volume with other logical volumes to form an LUSE volume (i.e., an expanded LU). For detailed information about LUSE, please refer to LUN Expansion User's Guide.


Besides the host modes mentioned above, the Host Mode drop-down list displays the Reserve host mode. Please do not select this host mode. 

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