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diskless booting via iscsi


iron man is anemic
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I dont know if they have covered this on a previous show or has been talked about on the forums before, but im wanting to know about diskless booting, and more specifically over iscsi. I know its possible, i just cant seem to get a straight forward answer as to what this takes to implement. Also, what would be the limitations of this, i mean could you conceivably boot from over the internet, provided both server and workstation had a fast enough internet connection? Anyone have any input? A possible idea for a future show?

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the way you would implement this is by network booting. On your iSCSI target host (just because why not) you would run all the stuff you need for network booting (DHCP, TFTP etc.). Then, as part of the image that's transferred to the client you would include the configuration necessary to connect to the iSCSI target.

While this can be done I would recommend you use NFS instead of iSCSI just because it is much easier to setup when doing this soft of thing.

Also, this is going to be any thing that isn't Windows only. See edit.

In theory an iSCSI initiator could be put in to the BIOS of a computer, then the OS just sees it as a normal hard disk, any motherboard that does this is probably really expensive.

Edit: Just looking, there is a PXE with iSCSI support available for Windows: http://www.doubletake.com/uk/products/netB...es/default.aspx

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Thanks everyone for the info. I know my nic in my desktop, and the one in my laptop already support network booting, i think its the pxe standard but i could be wrong on that. I just didnt know how to set it up so it would know what to boot from on the iscsi target if there were say more than one image or partitions to choose from.

would i need a second server as a man in the middle type setup? Basically to say oh MAC address (whatever) is trying to netboot, he needs x image/partition on the iscsi nas, let me initiate this for them and point the computer to the correct place. is that about how it works or am i totally wrong?

If not i would have to install firmware into my nic then, to be able to configure the iscsi san settings, so it knows where to go to retrieve the image correct?

Also can the os be a copy ie like in its own partition on the NAS server or would an image be the best? If an image is the best how do you adjust the file size since its essentially acting as the HDD and defining the parameters?

Ive read about 10 different things showing me all different ways to do this and i dont know whats right or even the best way to do it.

Its not something im going to implement long term, just something that i want to experiment with since im planing on building a iscsi server with esxi and freenas. Sorry for my rambling...

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PXE booting is not the same as iSCSI booting, for a start you will need a NIC that supports iSCSI booting as opposed to PXE booting. (This is where Etherboot comes in) PXE copies a small boot image to the local machine to run it, iSCSI uses the iSCSI protocol to access a remote disk over the wire. 2 very different things.

This video from Dell takes you through it.

This is not needed for ESXi, ESXi loads from a local storage unit (but can be run via PXE if you want) and then connects to an iSCSI storage array to use as persistent storage for the vm's to live on. You can run your VM's from iSCSI drives, but this is not really required and you loose the benefits of VMFS. Booting from iSCSI is used to lower power consumption and centralize storage in an environment where you still need the performance of actual hardware or some part of the hardware itself. An example of this is if you need to use CUDA on multiple nodes but the actual IOPS is fairly low.

Also FreeNAS is crap, use Openfiler instead.

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