On Wed, Nov 9, 2011 at 9:00 PM, Gordan Bobic <[email protected]> wrote: > 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 >> escalating. >> >> 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.
it is... until you work out the speed (he said... not having actually done it yet!) SD3.0 UHSv1 (whatever it is) qty 1 is _only_ 4 bits wide, and maxes out at... well, you can check the wikipedia page, off top of head i think 150mbits/sec is about the lot. by contrast, the NAND flash interface is ... *checks*...8, 16 or 32-bit wide, and you _can_ do "non-conflict" simultaneous 8 bands of DMA which matches with the 8 NAND select lines, obviously, so someone has thought about this :) that NAND flash, i seem to remember, somewhere, it supports up to 2ns NAND, so frickin 'ell that's 500mhz max, i don't dare look up the prices on those, but 8 of them all doing concurrent non-conflicting DMA transfers, i believe the point is made? :) probably horrifically expensive, too. >> 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. > :) yaay! well then that's gloody grilliant, it means CentOS is a breeze. yaay! > 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. yeah, precisely. the question is: would a bunch of NAND ICs beat the price or performance of off-the-shelf SSDs with SATA-II interfaces, and if so, how the heck do i justify it to the factory? btw they're set up - psychologically - for "tablets, netbooks, STBs", their heads would melt if i made any mention of "servers". so i believe it would be sensible to get the motherboard made elsewhere / somehow-else: a large 2-layer board probably would do the trick, even using KiCAD, hell there's got to be someone around with the expertise to lay out some tracks to an 8-port Gigabit Ethernet IC, bung on some SATA interfaces x8 direct to connectors, connect some I2Csx8 to an EEPROMx8, it's a cut-paste job! >> 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... a keyyboarrrdh? how quaint... :) sorry, my embedded experience dates back to the ETRAX 100mhz, the guys who did jffs i think it was... achh, too long ago to remember. > 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. yep that's easily doable. made a note. > Sign me up for some of those for sure. fantastic. > 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. ... Chip-selects with independent concurrent DMA x8 @ 500mhz, 32-bit? :) don't ask me how much those are, i don't know - anyone got a handle on the prices and capabilities of NAND ICs? l. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/capweedykk22_a6vxfwscfiwqxf7yqmpj9uy1udm4w6ykf_u...@mail.gmail.com
