[PetiteCloud] USB3 Flash for ZFS

Michael Thoreson m.thoreson at c4labs.ca
Thu Feb 13 18:23:27 PST 2014

Yes it can. ZFS Cache does not need to be the whole disk. In fact any 
ZFS does not have to be the whole disk and can be partitions (or slices 
for BSD).

So you could have the following:

FreeBSD labels USB3 Flash drives as dax

da0s1 - boot
da0s2 - host\petitecloud
da0s3 - vm storage
da0s4 - l2arc
da0s5 - zil - only useful with certain writes.

However there would have to be testing for certain OS and flash drive 
combinations. I am certain if it is solely a Windows limitation but I 
have never been able to get multiple partitions on a flash drive using 
windows but I have heard of people doing it so i assume they used a *nix 

The other option is using two flash drives as such:

da0s1 - boot + host\petitecloud + vm storage
da1s1 - l2arc

ZFS is able to mount disks based on their GUID's instead of device 
assignments which allows flexible use of external storage.

Michael Thoreson,

On 13/02/2014 8:01 PM, Aryeh Friedman wrote:
> Can this be used as a cloud on a stick? (i.e. I can take it out the 
> host that made it and stick into any FreeBSD capable machine and it 
> will boot PC and it's instances)
> On Thu, Feb 13, 2014 at 8:50 PM, Michael Thoreson 
> <m.thoreson at c4labs.ca <mailto:m.thoreson at c4labs.ca>> wrote:
>     I have confirmed that USB3 flash drives can serve as L2ARC caches
>     for ZFS. I am using a Kingston Hyper-x 64GB USB3 for my tests and
>     it significantly increased writes between 3 and 10 fold for
>     datasets with dedup set to verify.
>     Just thought this would be helpful for deployments where 100% SSD
>     nodes may be either impractical or out of budget and Ram capacity
>     is limited.
>     Michael Thoreson,
>     _______________________________________________
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> -- 
> Aryeh M. Friedman, Lead Developer, http://www.PetiteCloud.org
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