Why We Run VMware ESXi from SD or USB


  • Service Provider

    It is a commonly known best practice, both from VMware themselves as a vendor as well as from the industry to run VMware ESXi from a USB stick or SD card (depending on what you have available. SD is preferred.) It is easy to just think of it as a best practice and never contemplate why this might be important or, at least, beneficial but there are solid reasons for this and here are the ones of which I am aware:

    Top reason: both vendor and industry best practice. This goes a long way, you need pretty serious evidence to the contrary to contradict both the vendor AND the industry.

    But here is what leads to that:

    1. Cost. Anything else is just wasteful.
    2. Easier to migrate in case of host failure.
    3. No performance loss (the speed of the drives do nothing for ESXi).
    4. Reliability. SSDs almost never die in a read-only role. Disks wear out many times faster.
    5. Easier to swap when dealing with updates so that fallbacks to earlier versions are trivial rather than challenging. This is probably the top reason.
    6. Trivial to mirror automatically OR manually.
    7. Lower power consumption.
    8. Less heat generation.

    Trivial benetfts....

    1. More shock resistant.
    2. Lighter chassis.
    3. Less wasteful of disk capacity, if there even are disks locally.
    4. More flexible if moving between different modes like local storage and pure SAN.


  • It amazes me when I hear about people who install ESXi to the local disk/RAID. However, if you don't know any better, I can understand why people do it. They treat the hypervisor like Windows. But I remember the first time I upgraded an ESXi host with @alexntg and updated the SD card in a Dell Poweredge and watched him just reattach the VMs in the datastores. It all suddenly made perfect sense. Totally agree with the above. Well-written.



  • @handsofqwerty said:

    It amazes me when I hear about people who install ESXi to the local disk/RAID. However, if you don't know any better, I can understand why people do it. They treat the hypervisor like Windows. But I remember the first time I upgraded an ESXi host with @alexntg and updated the SD card in a Dell Poweredge and watched him just reattach the VMs in the datastores. It all suddenly made perfect sense. Totally agree with the above. Well-written.

    Well, I have it installed on the local RAID. However... We have a blade system, so there is no USB interface (without buying a multi feature adapter) and there are no SD card slots.
    In saying that, There is the local drive set and also a storage blade attached to it (where all the VM's are), so I guess it's as close to using an external drive as I'll be getting šŸ™‚

    I guess this could be used as another argument against blade systems.
    Ā 
    EDIT: This post contains incorrect information, found the SD and USB internal slots http://mangolassi.it/topic/5392/why-we-run-vmware-esxi-from-sd-or-usb/20


  • Service Provider

    @nadnerB said:

    I guess this could be used as another argument against blade systems.

    That would be it šŸ™‚ Is there really no SD or USB options? What blade system is that?


  • Service Provider

    When pricing blades, this would mean that the cost of two drives plus hardware RAID for every individual blade would be needed to be considered. Did the person buying the blades stop and consider that two drives plus entry level hardware RAID (probably coming to close to a $1,000 between the three things, I would guess) had to be added to the cost of every node compared to a traditional enterprise server node?



  • I honestly don't know if our Servers with ESXi where setup to run from USB/SD cards or not. Some of ours has front port usb & SD Card slots. And others don't. I'm not sure if there's a good way to dell from Vcenter, I might have to look in vSphere client on each host.

    Also for people that freak out about having it on SD instead of a RAID. just about every Cisco Router uses compact flash. Most other switches and routers are using some sort of flash media as well.


  • Service Provider

    @thecreativeone91 said:

    Also for people that freak out about having it on SD instead of a RAID. just about every Cisco Router uses compact flash. Most other switches and routers are using some sort of flash media as well.

    The ability to have dual (sometimes more!!) flash devices and to easily be able to manually swap them should they fail and to have spares at the ready really makes it even better with VMware than most networking and similar embedded devices because there are just so many simple was to mitigate the risk on top of it not being very risky at all. The biggest enterprises have depended on this design for a long time and no one questions it until it is about hypervisors.



  • I guess I've seen compact flash in routers, etc before..

    have you seen flash storage used in other products too? and I don't mean soldered on the boards.


  • Service Provider

    @Dashrender said:

    I guess I've seen compact flash in routers, etc before..

    have you seen flash storage used in other products too? and I don't mean soldered on the boards.

    Essentially anything that is embedded is this. Think about any appliance product which basically includes everything networking plus the majority of telephony, storage and monitoring products. If you don't see drives that you can remove, chances are this is what it is.



  • Sure. Is the flash used in those devices the same, more or less fragile than USB sticks or SD cards?


  • Service Provider

    @Dashrender said:

    Sure. Is the flash used in those devices the same, more or less fragile than USB sticks or SD cards?

    If they are new, should be the same. The same as SD which is more stable than USB simply because of the tight connection. USB sticks and SD cards are the same thing under the hood. But the connection of SD is very solid whereas USB is more loose. I know of no embedded product using USB, but many use SD or equivalent.

    Before this they used CF which was similarly solid but slower, bigger and more costly.



  • SD has really gotten to be a very solid technology. You almost never encounter one failing and they seem to last pretty much forever. Hard to beat them for the price.

    I wish that more things were designed to easily install to SD.


  • Service Provider

    @scottalanmiller said:

    I know of no embedded product using USB, but many use SD or equivalent.

    All of the EdgeMax routers use USB for their internal storage.



  • @scottalanmiller said:

    @nadnerB said:

    I guess this could be used as another argument against blade systems.

    That would be it šŸ™‚ Is there really no SD or USB options? What blade system is that?

    HP... interestingly enough. I don't see any options for SD on their propaganda pages.
    USB is available ONLY via propitiatory adapter šŸ˜ž and they are easliy bumped and broken as they stick out too far from the server.
    Ā 
    EDIT: This post is incorrect, found the SD and USB internal slots http://mangolassi.it/topic/5392/why-we-run-vmware-esxi-from-sd-or-usb/20



  • @nadnerB said:

    @scottalanmiller said:

    @nadnerB said:

    I guess this could be used as another argument against blade systems.

    That would be it šŸ™‚ Is there really no SD or USB options? What blade system is that?

    HP... interestingly enough. I don't see any options for SD on their propaganda pages.
    USB is available ONLY via propitiatory adapter šŸ˜ž and they are easliy bumped and broken as they stick out too far from the server.

    Some Proliant Server had internal SD card options.


  • Service Provider

    @thecreativeone91 said:

    Some Proliant Server had internal SD card options.

    All of their serious ones. He's stuck with the blades, though.



  • @scottalanmiller said:

    All of their serious ones. He's stuck with the blades, though.

    The type that DON'T stab. šŸ˜ž


  • Service Provider

    @nadnerB said:

    @scottalanmiller said:

    All of their serious ones. He's stuck with the blades, though.

    The type that DON'T stab. šŸ˜ž

    The ones that aren't too sharp? šŸ˜‰



  • @scottalanmiller said:

    The ones that aren't too sharp? šŸ˜‰

    The type you give the clumsy kid.



  • Just to confirm my babblings of fury, I pulled a part one of the older blades and found BOTH an SD card slot and a USB Connector... Buried under the HDD bay.

    Editing my previous posts now šŸ™‚


  • Service Provider

    That's much more reasonable then. I still don't like blades, but for them to be missing something that basic and critical was pretty surprising.



  • Is Xen Server viable for SD card?



  • @Engin00b said:

    Is Xen Server viable for SD card?

    XenServer supports SD Card installs. Not sure about Xen


  • Service Provider

    @thecreativeone91 said:

    XenServer supports SD Card installs. Not sure about Xen

    XS is just a packaging of Xen. So anything XS supports, Xen has to have supported. Xen is completely flexible and can be used anyway that you want, it itself doesn't have the same concept of "supported" like XS does.