EVA5k and Linux configuration

[Slawomir Gora]

Hi,
I have some question about configuration EVA5k and Linux systems

1. What should be value of "OS Unit ID" when Vdisk is created - I have found that for Tru64 or OpenVMS is must be unique number in SAN but what about Linux OS ?

2. What should be value of "Host OS" for host ?
a) Solaris ?
b) custom with Mode Number 000000002200282E

[Uwe Zessin · Accepted solution]

1) The "OS Unit ID" value is stored in a vendor-specific SCSI page. You can ignore it for all other operating systems.

2) For a 'normal' Linux (no Lifekeeper cluster), you should use 'SUN Solaris' and select a specific controller preference with simple failover (e.g. "Path A - Failover Only").

[Slawomir Gora]

Hi,

one more question about luns from os site without SecurePath

Eva3k - I see lun as 2 disks (each ontroller has one FC host port)

What about Eva5k ? - 4 disks or 2 disk (each controller has two FC host port)

[Uwe Zessin]

It completely depends on your setup and does not matter whether you have an EVA3000 or EVA5000. Both arrays use two controllers with two host ports each.

Without any multipathing feature you can potentially see up to four paths with a single fibre channel adapter if all ports are connected to the same fabric or down to one path if you use FC switch zoning as well.

Depending on your Linux version you can still achive some redundancy with a single adapter and without Secure Path if you enable multipathing in the Qlogic device driver. Information is here:
http://h18006.www1.hp.com/products/sanworks/multipathoptions/index.html

[Slawomir Gora]

Hi,

I know that it depends on my SAN configuration, but I thought about recommended Eva5k config:

Switch1:
ZoneDATA: hsv110a_fc1, hsv110b_fc2, server_fc_1

Switch2
ZoneData: hsv110a_fc2, gsv110b_fc1, server_fc_2

separate zones for SMA

As I see I can present LUN only to Path-A or Path-B.
What is Path-A, both ports fc1 and fc2 from conntroller 1, can I configure trafic explicite to fc1 or fc2 port ?

[Uwe Zessin]

No, the EVA will always present a mapped virtual disk through all 4 controller ports. But the path selection of a virtual disk tells the EVA which controller 'owns' it and cares about the I/Os.

The other controller presents the virtual disk, too, so that the multipath component in the operating system is aware of any standby paths. However, if you attempt to do an I/O through this controller, you will receive a 'not ready' response.

This selection is per-virtual disk, so you can divide them over both controllers. Makes sense as this will use CPU and cache of both of them.


Choosing Path-A means that you can do I/O to a single virtual disk through both host ports of Controller-A at the same time. It depends on the multipath driver whether your server can do that.

Taking you setup as an examle: with Secure Path and 'load balancing enabled' you could do I/O via both fibre channel adapters to both host ports of the same controller, but if I recall correctly, you cannot do that with the Qlogic multipath driver.

There is a management component on Qlogic's website called 'sansurfer' which should allow you to choose which target port the driver is directing traffic for a LUN (I haven't had time to play with it, yet - there is only so much time ...). Unfortuately, it is not supported by HP :-(

[Slawomir Gora]

Hi Uwe,

Thank you.