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Re: [Arm-netbook] 9nov11: progress on allwinner A10

On 09/11/2011 20:44, Luke Kenneth Casson Leighton wrote:
ok, just a quick thoughts / status update.

we've had it confirmed that the CPU is external 2gb addressing but
*internal* limited to 1gb (!)

little factory is still going over the BOM, but want to put in 512mb
DDR RAM ICs because they're cheaper.

That's a shame. IMO the biggest shortcomming of available devices is small RAM. I can just about live with 1GB, 2GB would be nice. Especially since the development version of OLPC is available with 3GB (Marvell).

they were planning to make room for up to 4gb NAND flash *but*...
something just occurred to me / my associates: thailand's under water.

the implications of that are that the factories which used to make
low-end IDE drives and pretty much every SATA drive under 80gb no
longer exist... and probably won't ever be rebuilt.  everyone's moving
to SSDs for low-end, and the prices for larger HDDs are rapidly

now, for free software developers we don't give a rat's arse: there's
always room to cut down to emdebian, or use cramfs, or... whatever:
there's always creative ways to make a bit more room, but i've been
connecting the dots a bit from various peoples' input, talked it over
with my associates and we came up with an idea.

I'm not sure what the point is of having internal flash if you have a SD/uSD slot AND a SATA port. Dropping internal NAND alltogether seems like an obvious choice.

alain (williams) asked a very pertinent question, he said, "ok yep
count me in, but how do i make any money from this?" and it put me on
the spot and i went, "um, well... how about you do servers but use
these as low-power ones" and then i realised of course, he's a CentOS
maintainer, hosts some packages, so he's going to try CentOS for ARM
and then well if that works, he'll be the maintainer of the ARM port
of CentOS servers.

I may have beaten him to it. I have a beta spin of RHEL6 port for ARM running right now with all relevant packages patched as required and built. :)

If anybody is interested in it, drop me a line and I'll notify you when it is downloadable (probably about a week, two at the most).

then we put two and two together and went, "hang on, these are
effectively blades, why not have a chassis like the ZT-Systems one,
with a gigabit backbone, space for SATA drives, and up to 8
EOMA-PCMCIA-compliant CPU cards, each with 1gb DDR3 RAM and these
Cortex A8s?" it'll all be low-cost, you can get 40gb to 80gb SATA
drives, turn it into a big software RAID or NAS box or a
high-performance (but higher-than-average latency of course)
load-balanced server aka cloud jobbie.

I like this idea - A LOT. I'd certainly be interested in buying some.

at which point i went "oh shit - low-end SATA drives don't bloody
*exist* any more!" :)  [look on ebuyer's site for SATA drives below
£50 - there aren't any].

Well, on something this low power you'd want SSDs anyway.

so _then_ i thought, hang on, NAND flash ICs in SSDs are like,
dropping like a stone as they pick up the slack from the fact that
low-end SATA and IDE drives don't exist, hmm, and the spec on the
allwinner CPU says that it has 8 NAND chip-select lines... why not ask
the little factory in shenzen if they can make room (on the other side
of the PCMCIA card) for another 7 4gb NAND flash ICs?

so if you wanted a "cheap" low-cost version, it'd be 512mb RAM with
maybe a single 1gb NAND flash IC; the next version up would be 1gb RAM
with a single 4gb NAND flash IC (again, single-sided so it's a cheaper
build cost); the insane version would be effectively its own SSD with
up to 32gb NAND flash, potentially 8x the speed of the 4gb version,
and people could do their own wear-levelling (i hope!), i remember how
everyone keeps bitching about how these bloody SSDs always get in the
way with the stupid, stupid assumption that there's going to be a FAT
or NTFS partition on it.

Hmm... Doing your own wear leveling? How quaint...

bottom line: anyone grok the above, would want to sell these
"promised" ARM-based servers we keep hearing about, but like, y'know,
actual real ones, please do speak up, and i'll see how to arrange it.
bear in mind that, thanks to the EOMA-PCMCIA specification, it will be
possible to swap out the CPU cards with anything else that comes along
in the future which also has 10/100 ethernet and SATA-II (possibly a
Cortex A9 which would then have virtualisation - A8s *don't* have
virtualisation), but no, you can't have 10/100/1000 or SATA-III this
really _is_ at the "low-cost" and "low-power" end, going a bit on the
odd side perhaps, pushing that "low-power equals a bit higher latency"
thing a bit further along than is usually expected, but i believe the
concept has merit.

but... what's more important than what _i_ think has merit is what
_you_ think has merit :)

I think the server idea is _great_, provided it has at least 1GB of RAM per board, a SATA port and at least 100Mb networking. Sign me up for some of those for sure. OTOH, I am not sure I see the point of having on-board raw NAND instead of a uSD slot. Yes, even the fastest SD cards are painfully slow when it comes to write IOPS, but arguably raw NAND won't be all that much better for any serious workload. In reality, I don't really see it getting used in a server setup except for a few KB for uboot settings. Everything else on a server will be on an SSD.


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