While
blade servers offer numerous advantages in virtualized environments (such as
easy scalability, minimal cabling, and ease of setup) as VDI has progressed
beyond simple desktop OS virtualization, blades have some significant drawbacks
that leaves them less than ideal for hosting a modern virtual desktop if one
expects near traditional end user computing performance.
I'm currently architecting a second generation VDI deployment that currently resides on HP blades. As the BL685c G6's are approaching five years of age and aren't on the ESXi 5.5 compatibility list, it's time for an update. With modern developments such as Teradici offload cards, nVidia GRiD accelerated graphics, and affordable PCIe SSDs here is why I'm planning on moving the desktops onto newer standard rack mount 2U hosts.
1.) Limited Graphics Capabilities
To
provide the display performance that a typical user is accustomed to,
additional graphics power is necessary.
Most traditional servers include minimal onboard graphics capability and
in order to add extra graphics power, you need a PCI-e slot. While these slots are available in other form
factors, such as tower and rack servers, blade options typically don't include
a lot in the way of advanced graphics capability, and when they do it adds complexity or expense.
The
manufacturer proprietary mezzanine form factor that most blades have for
expansion cards limits the expansion capabilities for the blades because it
typically takes an extended period of time, sometimes years, for a particular
type of card to become available in this form factor (usually either due to the
time it takes a server vendor to certify a card or the time it takes a third
party vendor to redesign the card into this form factor.) Also mezzanine cards are sometimes are not backwards
compatible with previous mezzanine slots.
For instance HP completely redesigned the mezzanine cards in their G8
generation of servers making them completely incompatible with the mezzanine
cards from their older G6 and G7 generations (and vice versa, you cannot use a
G8 card in a G6 or G7 slot). PCI-e is an
industry standard and a newer slot can nearly always utilize cards designed to
an older specification.
3.) Local disk storage options for blades are limited and/or expensive