Archives For October 2010

You are in front of a Linux box, a VM really, with a bunch of new disks that must be configured and suddenly you remember that there is no ioscan in Linux, you will ask yourself ‘who is so stupid to create an operative system wihtout ioscan?’ at  least I did x-)

Yes it is true, there is no ioscan in Linux and that means that everytime you add a new disk to one of your virtual machine you have to reboot it, at least technically that is the truth. But don’t worry there is a quick and dirty way to circumvent that.

From a root shell issue the following command:

[root@redhat ~]# echo "- - -" > /sys/class/scsi_host/<host_number>/scan

After that if you do a fdsik -l will see the new disks.

If you want to rescan your box for new fiber channel disks the command is slightly different.

[root@redhat ~# echo "1" > /sys/class/fc_host/host#/issue_lip

For the fiber channel part there are also third party utilities. HP for example provides hp_rescan which comes with the Proliant Support Pack.

[root@redhat /]# hp_rescan -h
hp_rescan: rescans LUNs on HP supported FC adapters
Usage: hp_rescan -ailh[n]

-a: rescan all adapters
-i: rescan a specific adapter instance. The specific device should be a
 SCSI host number such as "0" or "6"
-l: lists all FC adapters
-n: do not perform "scsi remove-single-device" when executing probe-luns
-h: help
[root@redhat /]#

If you know other ways to rescan the SCSI bus in a Linux server please comment :-)


HP resources for VMware

October 20, 2010 — 2 Comments

The reason for this post is trying to be a single point of reference for HP related VMware resources.

I created the list for my personal use while ago but in the hope that it can be useful for someone else I decided to review and share it. I will try to keep the list up to date and also add it as a permanent page in the menu above.

General resources

VMware on ProLiant

HP StorageWorks


vCloud Director

If you are a user of the P4000 VSA you’ll be use to the quiet boot sequence of the SAN/iQ software. Just a couple of messages until you get the login prompt.

But how about if anyone want to watch the whole boot process to check error messages or something alike? There is an easy and simple solution, at the begining of the boot sequence press ESC in order to stop the bootloader and when the boot: prompt appears type vga and press Enter.

After that you will have a normal boot process like with any other Linux system.


Although I work at HP, a few of days ago I decided to try the Cisco UCS Platform Emulator. I’ve been using HP blades and Virtual Connect for years so I thought that it would be great to get a small taste of its most direct competitor. And, of course, this is my blog and not an HP blog so I can try and write about anything I want :-)

The UCS Platform Emulator can be freely downloaded from the Cisco Developer Network here, you just need to fill a small form. It is also very recommendable to grab a copy of the emulator guide here.

The emulator is virtual machine with a Linux CentOS inside, you can run it with VMware Workstation as I do or with the free VMware Player. After firing it up, the startup process will go like any RedHat based Linux until you will get to a Starting cisco_ucspe messge. Then It will start to decompress and install the “real” emulator into the VM.

After that process is finished you will get to login screen that ask you to use the user and password config in order to access the configuration menus of the UCSPE. From those menus you can set stuff like the number of UCS chassis to be used and the number of blades per chassis for example.

Once you have configured the emulator point your web browser to the IP address of the emulator to access the UCS Manager. The network the UCSPE virtual machines is connected to must be configured to provide IP addresses with DHCP, I used the default NAT network the UCSPE came with.

When you are in the web browser click the LAUNCH link.

And here it is, in all it magnificence… the Cisco Unified Computing System Manager.

From here I will get familiar with the manager and try things like UCS Service Profile creation or playing with the UCS API. I will try to write about it in a future post.

Just a final word. I am very pleased with emulator; have to admit that Cisco did a great work, the whole “thing” was up and running in a breeze and provides you with a very almost-real experience of the UCS platform.

I firmly believe that this is the correct direction that every vendor should follow, yes including HP. If they release simulators to the IT people out there, in the end it will beneficial for them.