[Xen-users] Re: With regard to questions on xen-dev about memory and disks

[Ernst Bachmann <e.bachmann@xxxxxxxx>]

On Tuesday 27 September 2005 18:21, you wrote:
> With regard to questions on xen-dev about memory and disk,
> i saw the following advert:
>
> http://www.hyperossystems.co.uk/07042003/products.htm#hyperosHDIIproduct
>
> in short it's a 5 1/4" bay you can put in RAM dimms and use them as a
> harddrive.
> It has reboot-memory and 160-minutes-power-off memory.
>
> They advert it at 80x faster than harddisk so, as swap space, or tmp-space
> on domU (proxy-cache, mail/spam/virus handling etc etc etc) it would be
> maybe worth the investment. What do you guys think?
>
All in all nice features, but:
80x faster can only apply to seek time, the bulk transfer rate would be 
limited by the ide (or SATA) interface, even with SATA-II it would max out at 
300something MB/second.

While seek time is important for swap speed, I think the memory would be more 
usefull on-board (with 64bit access or PAE)

(BTW, thats basically what PAE does: it uses the memory beyond the CPU's 32bit 
address limit as "fast swapspace")

Maybe an option if your mainboard/CPU are maxed out RAM-wise, otherwise invest 
in 4 fast sata-drives, put a swap partition on each (with same priority, so 
its striped) and you'd get about the same bulk transfer speed for the same 
price + hundreds of gb additional storage space for free...

/Ernst

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