Re: [Xen-users] Boot XCP from USB Stick - Anybody already did it - How might this be done ?

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

>>> On 2013/01/26 at 09:23, Andreas Balg <a.balg@xxxxxxxx> wrote: 

> Hello everybody,
> 
> we'd like to install and boot the XCP (1.6) Hypervisor from a
USB-Stick 
> - Why? We'd like to migrate from a couple of ESXi-Servers  -which are
in 
> fact IBM-Blades sold with the ESX integrated. Those are installed on
2GB 
> USB-Sticks as well that are installed inside the blades.
> 
> So far I've been able to find some industrial grade USB-Sticks of 
> 4Gb/8Gb that are specified to operate at temperatures up to 85*C
(inside 
> a blade server) and are built using SLC-flash. Those are specified at

> MTBF of 5.000.000 hours of operation without the usual wear of flash

> cells - even at high I/O rates. So this should easily be very good
for 
> reliable dom0 operation. DomUs are planned to be kept on FC-SAN - But
I 
> absolutely do not want to boot from there
> 
> Why not install it on some small HDD? - those purpose built IBM 
> Blade-Servers have no internal connectors for sas or sata disks but
are 
> already installed at that customer site
> 
> Anybody been able to compile usb-drivers for the installer or a
kernel 
> with built in drivers for USB or create a bootable image to be copied

> directly to a stick?
> 
> Any ideas of how to get this started ? Anybody did it before?
> 
> Cheers
> Andreas Balg
> 

Andreas,
I have done USB sticks once, but right now I'm actually operating off
of SDHC cards.  Several of my servers have built-in SDHC slots, and I
bought a bunch of 16GB cards to use for the install.  There wasn't
really much to it - I just ran the install with the cards in and
installed to the SDHC card.  There are a couple of things to note:
- XCP requires at least 8GB of space on the destination device, so your
USB or SDHC devices need to be at least that big.  Mine are 16GB, so no
trouble.
- I was very careful to *deselect* the SDHC and/or USB devices as
destinations for VMs.  The wear on the flash memory from the basic XCP
operations (logging, really) should be minimal, so you should get pretty
good life out of them for just running the XCP system.  However, if you
try to put VMs on those things, you have an entirely different problem
and will probably wear the flash out quickly (depending on what the VMs
are doing).  My storage is all iSCSI and/or NFS shared, so I'm not
relying on local storage.
- You don't need to compile the usb-storage.ko driver for XCP - it's
already compiled.  You do, however, have to go in after the install and
tell the system to load the driver.  This is pretty simple - just
re-generated the initrd via the following command:
/boot/initrd-2.6.32.43-0.4.1.xs1.6.07.734.170748xen.img.cmd --preload
usb-storage

Note that the actual name of the "initrd-<version>.cmd" file in /boot
may vary based on the release of XCP you're running - mine is one of the
beta ones right now, so the build numbers there at the end are probably
different from the official XCP release.  But, basically it's just
running the CMD file with the option to load usb-storage, and it should
be good to go.

-Nick


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