| Scyld ClusterWare HPC: Administrator's Guide | ||
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One of the unique advantages of Scyld ClusterWare is the fast and flexible boot procedure for compute nodes. The Scyld BeoBoot system is a combination of unified booting and a carefully designed light-weight compute node environment. The BeoBoot system allows compute nodes to initialize with a very small boot image that may be stored on a wide range of boot media. This small boot image never has to change; however, Scyld ClusterWare's boot setup allows you to change the kernel the compute nodes run, the modules that are loaded, and every aspect of the application environment by changing a few files on the master node.
This chapter gives instructions for setting up different types of boot media for the compute nodes, changing various settings that control the boot process, and checking for boot error messages. A detailed description of the boot process is included in the ClusterWare technical description in the Chapter called Scyld ClusterWare Design Description.
There are several ways to boot a compute node with Scyld ClusterWare, as discussed in the following sections. The methods described are all interchangeable, and they work seamlessly with each other. Thus, you can have some of your compute nodes boot using one method and other nodes boot with a different method.
Note that booting from local hard disk is no longer supported by Scyld ClusterWare. Contact Scyld Customer Support if you require this capability.
Booting from a floppy disk is easy to set up. However, this method slows down the boot process, as it takes a while to load the image off the floppy disk.
To create an etherboot floppy for a compute node, open the BeoSetup GUI and click Node Floppy in the toolbar, then browse to your floppy drive in the dialog box that opens.
After creating a floppy disk for each compute node and putting these floppies in the nodes, you will need to make sure that the BIOS on each node is set up to boot from floppy disk.
To create an etherboot CD for a compute node, open the BeoSetup GUI and click Node CD in the toolbar, then browse to the appropriate ISO image in the dialog box that opens.
PXE is a protocol that defines a standard way to netboot x86-based machines. In order for PXE to work, your compute nodes must have support for it in both the network adapters as well as the BIOS. The option to PXE boot must also be turned on in the BIOS. This is the preferred method of booting nodes in a Scyld cluster.
Linux BIOS is a project to replace the BIOS of a machine with Linux. This greatly speeds up the boot process as most of the actual work done by the BIOS is designed to make things like DOS work, but which aren't really needed by Linux.
There has been work done by third parties so that it is a Scyld ClusterWare initial image that replaces the BIOS. This has the advantage that all you need for a compute node is a motherboard with ram, processor, built-in network adapter, and a power supply.
Linux BIOS is not supported by Penguin Computing, Inc., however you can see http://www.linuxbios.org/ for more information if you are interested.
Although not Scyld specific, using a flash disk is mentioned as it can increase cluster reliability. A flash disk is a solid state device using an Electrical Erasable PROM (EEPROM). The devices are seen by the BIOS as an IDE or SCSI hard drive, and support all normal drive operations, including running beofdisk and installing the initial boot image. This allows a node cluster configuration with no moving parts other than cooling fans, and is an alternative to using the Linux BIOS. These devices are faster and cheaper than hard drives, and are currently limited to 4 MB to 512 MB. But, for booting, less than 2 MB would be needed.
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