The new M3 Blades come with an optional SD Card
Have not used the SD cards but don’t like the idea, or local drives. Hope I don’t sound like an old man! Both of those give blade’s a “personality” as the UCS term goes, and blades should never have a personality. With a personality (any lack of 100% hardware abstraction) the UCS turns into sudo physical racked servers. Or worse yet an old-school coal burning HP Blade system. If the blade dies you have to put the SD Card in another blade. That isn’t the idea of UCS. UCS is supposed to be 100% hands off after setup, other than break fix, but with a buffer of time allowed except for big failures like an FI. But even then you don’t have to run, or be to the datacenter in the next 15 minutes.
Go with boot from SAN, or boot from iSCSI. Most NAS devices support iSCSI. iSCSI is kind of a pain to setup per Blade/Service Prifile. Checkout http://www.freenas.org/ and a JBOD. I like iSCSI for boot because it removes the need for SAN altogether. Some PowerShell is needed to make deploying the iSCSI quicker than I do by hand right now.
For SAN the cheapest HP EVA, or Hitachi device is plenty. If there is already SAN in the environment Boot LUN’s only push 16k iops every 100 servers (Windows 8 R2 64 bit) at boot time. And that is just for like 15 seconds. Then the average IOPS for a running server is like 5 per server tops. Xiotech makes a nice device also.