Possible to use Device Mapper Multipath (RHEL 5.4) with a single HBA (single path)?

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Hi,

 

We have a single Qlogic 2560 HBA with one port (single path) that we will be configuring and it's not clear to us from reading the RH DM Multipathing guide (RHEL 5) whether we can use Device Mapper Multipath (DM-MP) with a single HBA.    We have plans to add a second HBA in the future but the immediate plan is to use the single HBA. 

 

Question:  better to configure the HBA card with device mapper now (single HBA) or don't use Device Mapper Multipath until we actually have two HBAs - we'd prefer to create the Device Mapper Multipath device with the single HBA now/upfront to avoid the need to do this in the future when we add a second HBA (multipath) if possible and supported.   I'm not not clear if Device Mapper Multipath can be used with a single HBA (single port).    If DM-MP not a good (keep in mind plans to multipath within 2 months) then we just present the LUN and use it much like it was direct attached to array...

 

Some details:

 

[root@xxx tmp]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.4 (Tikanga)
[root@xxx tmp]#
 

[root@xx tmp]# systool -c fc_host -v
Class = "fc_host"

  Class Device = "host7"
  Class Device path = "/sys/class/fc_host/host7"
    fabric_name         = "0x2000001b3294a2df"
    issue_lip           = <store method only>
    node_name           = "0x2000001b3294a2df"
    port_id             = "0x000000"
    port_name           = "0x2100001b3294a2df"
    port_state          = "Online"
    port_type           = "Unknown"
    speed               = "unknown"
    supported_classes   = "Class 3"
    supported_speeds    = "1 Gbit, 2 Gbit, 4 Gbit, 8 Gbit"
    symbolic_name       = "QLE2560 FW:v4.04.09 DVR:v8.03.00.10.05.04-k"
    system_hostname     = ""
    tgtid_bind_type     = "wwpn (World Wide Port Name)"
    uevent              = <store method only>

    Device = "host7"
    Device path = "/sys/devices/pci0000:00/0000:00:03.0/0000:0d:00.0/host7"
      ct                  =
      edc                 = <store method only>
      els                 =
      fw_dump             =
      nvram               = "ISP "
      optrom_ctl          = <store method only>
      optrom              =
      reset               = <store method only>
      sfp                 = ""
      uevent              = <store method only>
      vpd                 = "+"

[root@xxx tmp]#

 

[root@xxx tmp]# multipath -ll -v2
[root@xxx tmp]#
 

 

Recommendations/insight is appreciated.   Thanks in advance for your consideration.

 

Jason

JW

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