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Boot from the SAN with iSCSI

This tip details the advantages of booting from the SAN instead of locally.

This article first appeared in "Storage" magazine in the May issue. For more articles of this type, please visit

What you will learn from this tip: Advantages of booting from the SAN instead of locally.

In case you were looking for a reason to deploy an iSCSI SAN, here's another: You can boot your servers remotely off the iSCSI target.

Today, software initiators for Linux allow you to remote boot from a SAN through PXE (pronounced "pixie") boot support. iSCSI host bus adapters (HBAs) such as Adaptec's 7211 and QLogic's QLA4010 and 4040 families support iSCSI boot, as do Alacritech's new SEN2000 and SES2000 cards. If you're running Windows and want to bypass an HBA, Canadian firm emBoot last month announced netBoot/I, an iSCSI software initiator and network boot suite for Microsoft environments that will sell for less than $100 per client.

Why boot from a SAN, you ask? "If I have to install a new server without diskless boot, it takes four hours; but with diskless boot, it takes a couple of minutes," says Bo Christiansen, a consultant with Danish IT consulting firm SDC Udvikling. SDC recently implemented an IP SAN from EqualLogic. Supporting the IT infrastructure of 80 Danish financial institutions, SDC's servers are equipped with Adaptec 7211C HBAs and boot from the EqualLogic array.

Other reasons people prefer booting from a SAN over local boot include better disaster recovery and quick redeployment of server resources, says Steve Spellicy, product marketing manager at EqualLogic. For example, by replicating boot volumes off site, you can quickly restore a server by booting it off the remote boot volume copy.

Microsoft hasn't made up its mind about boot from SAN. "We are hearing about remote boot on SAN, but it's not supported by the initiator today," says Claude Lorenson, Microsoft's senior product manager of storage technology. "There are projects in place to make things simpler, but how far we are going to push it, I don't know yet."

That's understandable given how Microsoft has architected its boot process, says George Kostiuk, president of emBoot. Speaking of netBoot/I, "we had to do some low-level lipstands [sic] to make this work," he says. "It wasn't easy to make it do what it does."

For more information:

Advice: Is it possible to SAN boot using an iSCSI adapter?

Topics: SAN management and admin

Learning Guide: SAN

About the author: Alex Barrett is Storage magazine's trends editor.

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