Today we’re going to take a look at booting RHEL 6.1 x86_64 from a NetApp iSCSI LUN, but first we’re going to take a look at why we would want to do this in the first place. Sure, it’s cool from a techie standpoint, but to do this in the data center requires a compelling argument.
- Centralizing the boot disks means that backup and DR is vastly simplified. You don’t need a separate backup network to all of your servers, or even just your critical servers. Provided you have the proper configuration and procedures in place for your storage, entire volumes of boot LUNs or individual boot LUNs can quickly be restored.
- Using NetApp as the backend storage will actually reduce the overall footprint – as long as Deduplication is enabled and all FlexVols LUNs are thinly provisioned.
- All the benefits of an FCP boot solution, without the add infrastructure costs of FC switches, FC HBA’s, or dedicated FC SAN frames.
- Additional flexibility above and beyond FCP when used in conjunction with NetApp MultiStore. MultiStore provides the feature of ‘vFilers’ – in short, lightweight instances of Data ONTAP that can be moved from physical controller to physical controller as necessary. The concept is similar to that of a virtual machine on a hypervisor. (I see another blog post idea….)
So, what did I use as far as equipment? Here’s a run down of the components involved:
- NetApp FAS3170 (any FAS controller would have been fine)
- Fujitsu Primergy RX200 S6 Server (I like the iSCSI boot capable onboard NICs)
- Cisco Catalyst 4948 Switch (ubiquitous switch)
NOTE: This is a DVD install only, but I promise I will put up another post that covers the iSCSI boot install via Kickstart in the near future.
Here’s what I did to install and boot from the NetApp iSCSI LUN:
I created an iSCSI LUN, an igroup (initiator group), and mapped the igroup to the LUN on the NetApp controller:
> lun create -s 40g -t linux -o noreserve /vol/boot_vol/boot_lun > igroup create -i -t linux igroup_rhel6 iqn.2010-04.com:fujitsu.rhevh1 > lun map /vol/boot_vol/boot_lun igroup_rhel6 0
Specifically, this creates a 40GB thin provisioned LUN optimized for Linux, in the /vol/boot_vol volume. The iSCSI igroup is created and contains a single iSCSI initiator that is then mapped to the LUN we created. (What I didn’t show was that I also created a VLAN interface just for iSCSI traffic and that the switch port is configured for that same VLAN.)
Next, I booted the Fujitsu server with the RHEL 6.1 ISO, and waited for the prompt to configure the onboard iSCSI and typed [CTRL-d], where the following menu greeted me:
NOTE: If there is not a default gateway on the storage network, then “fake it” by entering in the IP of the storage target to avoid ‘dracut’ complaining that it can’t resolve the gateway via ARP.
I exited the menus, saved the configuration and rebooted to the RHEL 6.1 ISO.
Go through the installation menu as normal until you reach the screen below, where you will select Specialized Storage Devices:
So there we go – it’s all very straightforward. This is a perfect solution for the non-FCP datacenter that still requires or prefers SAN boot. All of the Storage Efficiencies are still available, DR & backup are easier to plan and deploy, and added flexibility – but without any additional infrastructure cost with added.
That’s a win-win-win in my
thanks for reading,