Booting Windows from the SAN
Booting a Windows 2000 server from the SAN is useful in a disaster situation where the main server may be unavailable.
Normally Windows boots from a disk attached directly to the main server. But if the server with the boot LUN has crashed or is otherwise compromised, it can take extra work to boot the system from another server. A number of products offer boot-from-SAN abilities for Windows SANs, among them Hewlett Packard's SANLink and Dell's Powervault 530F. Both of these are SAN appliances that run as part of the SAN rather than as servers. With such a device installed a new server can be designated, either locally or remotely, and booted from the SAN array instead of a local disk attached to the server. Here's how Dell describes the process with its PowerVault 530. " Each Windows NT or Windows 2000 server on the SAN can be configured with its own virtual boot device.
The boot device is mapped by the PowerVault 530F to appear as LUN 0 to the server, a requirement of these operating systems. If one server fails, a new server can be brought online by booting it from an external SAN disk array instead of its local disk. In addition, this boot device can be mirrored to a remote site, so in the unlikely event of a primary storage array failure, the server can be mapped to the remote boot device."
Hewlett Packard discusses its SANLink performance, including booting from the SAN, in a white paper at: www.hp.com/products1/storage/san/sanlink/white-paper.pdf.
The design for a SAN using boot from SAN is sketched at: http://www.1perscom.army.mil/DOIM/Documents/Architecture.htm
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Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
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