PCMCIA bandwidth?

[syadnom]

i have a laptop happily running gentoo. the problem is that this machine has a 4200RPM hard disk that is DOG slow when i'm multitasking.

i'm toying with the idea of gigabit ethernet and a drive storage machine( i have 8 120GiB disks and a number of 40,60,80GiB drives), then mounting these via iSCSI.

the question is,what kind of bandwidth does a yenta-based PCMCIA slot have??

GibEth =~125MiB/sec
PCI32/33=~132MiB/sec
PCMCIA=??

i'm worried that the PCMCIA bus is much slower and would defeat the purpose, as a PCI is completely saturated with the GibEth's 125MiB/sec + access to local disk, would the PCMCIA bus suck?

and yes, i'm set on iSCSI, i have starport & starwind running on the windows network here and remotely mounted iSCSI disks are litterally 50% faster than a SMB or NFS share! raw block access to the media is very nice how ofter do you get to fdisk a remote drive

[bk0]

From what I understand, PCMCIA slots are usually bridged to the PCI bus so that's the bandwidth you need to be concerned with.

[y0zza]

Yes, 32-bit Cardbus PCMCIA has a theoretical maximum throughput of 132MB/s with bus-master ability, and uses a bus protocol very similar to PCI. Older 16-bit PCMCIA cards run at ISA bus speeds (~8MB/s), however.

[syadnom]

my PCMCIA slot is cardbus capable, so i just need to find a cardbus GibEth.

thanks

[tightcode]

Just a quick note. You will need a cardbus (32bit) card for the kind of speeds you are talking about.
I haven't worked with pcmcia's for external hard drives but I have worked with them extensively for writing to compact flash media.
From my experience a non cardbus, 16bit pcmcia compact flash card reader/writer will not exceed about 5Mb/s even if the compact flash card supports higher speeds (note the bandwidth specs mentioned by other users).
Because I work with 4GB CF cards those speeds are too slow. I bought the one 32bit Cardbus PCMCIA CF reader/writer available (It is amazing that there is only one on the market!) but it unfortunately doesn't work under linux, and only has partial and buggy OSX support from what I have read.
The reason I bring this up is that I thought there would be no problem getting it to work under linux as I have actually had better luck getting most "odd" hardware running under linux than under win32. This 32bit Cardbus CF reader is however an exception.
I hope your search for a 1000baseT pcmcia 32bit cardbus adapter will yield more choices and ones that will work. I would suggest thurough research first, it may save you a good sum of money.

Cheers,

TightCode

Post Scriptum: the card I have which doesn't work is a Delkin Devices eFilm PRO Compact Flash CardBus Adapter.

[nickd]

Hello TightCode

[tightcode]

Sorry for taking so long to answer. The answer is a bit vague and two-fold but here goes:
Yes & No

Someone did introduce some patches which work although not quite at full speed (yet). These however haven't made it into the upstream kernel sources (yet).
Later today I will dig up the info for you and maybe submit a request to the gentoo-dev-sources to have them included since I suspect they will be added to the official kernel sources soon. So yes there is hope I just haven't bothered with it in a while. I will refresh myself with where I got the kernel patches from (and whom did them) see if they are going to be included soon and then drop that info in here for you.

Update: Well here you go I just looked this up. Dan B. brought this to my attention and I owe all the thanks to him !
Mark Lord wrote the patch, and it is included in the Alan Cox kernel sources since 2.6.9-ac4.
Here is I think the first sight of success: http://lists.infradead.org/pipermail/linux-pcmcia/2004-October/001166.html
I just checked it appears this is not in the current gentoo dev sources kernel. I am posting a bug report now and will include the link in here. Feel free to add a comment to the bug report yourself:
https://bugs.gentoo.org/show_bug.cgi?id=85870


Cheers,

TightCode

[nickd]