----- Original Message ----- From: "MonMotha" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, July 06, 2003 1:31 PM Subject: Re: [luau] No hard drive, only compact flash card
> Matthew John Darnell wrote: > > Aloha, > > > > Does anyone have any experience with booting and running an full Linux > > server install from a 1.0GB CompactFlash Cardor similar. > > > > By full server install I mean, apache, sendmail, mysql, gc++, etc. No X > > needed, only command line. > > > > Seems like it would be possible, 500MB for the OS and 50MB for the apps. > > > > I wonder how fast/slow they are for access compared to a hard drive. > > > > I see 1.0GB card for $299 retail, they will only be getting > > cheaper/faster/higher density. > > > > Aloha, > > Matt > > > > CF cards are *VERY* slow compared to hard drives, especially on writes. My > little 32MB things can manage about 1-4MB/sec reads, but only about > 100-300kB/sec writes! This is *REALLY* slow. You will NOT want to even THINK > about swapping to it. In other words, make sure you have enough RAM because > there won't be any swap. RAM is cheap these days, so this shouldn't be a > problem. However, last time I checked, distros like redhat likes to complain a > lot if you didn't set up swap for them (I think it used to be that redhat would > refuse to install under such a situation?) > > People tend to overexagerate the erase cycle limitations of flash. CF cards > usually do wear patterning to prevent the same sectors from being used over and > over, and when they have reached their max usage, that sector is just no longer > used and is remapped (like bad sectors on IDE hard drives). The entire card > isn't useless. If you're really concerned about this, you can get nicer flash > cards that actually present themselves as raw flash, rather than ATA flash, and > run a real flash filesystem like jffs2 on it. jffs2 includes on-the-fly > compression (which I think can be disabled, but may actually help with > read/write speed in this case), and all the bad block handling/wear patterning > you could need. I was told once the "best" minimalist distro was debian. I sure like the functionality of apt-get. An IDE to flash adpater runs about 30 bucks, a lot less than I thought it would. > However, due to their slowness at writes, I'd reccomend keeping really dynamic > things like /tmp in a ramdisk (use tmpfs, it takes up only as much ram as it > needs to based on what's in it). You might also want to do something with /var > (like unpacking it to a ramdisk at startup, then tarring it up back to CF at > shutdown, of course this makes unclean shutdowns REALLY bad). Or, you could > just not have logging to /var/log and simply use a ring buffer like is used by > busybox's syslog. I will have to research jffs2 and busybox. > I'm still curious if even 500MB would be needed for "the os". You seem to be > used to very bloated desktop oses (like redhat) that are designed to have > everything abstracted two or three times (remember, you can always fix the > problem by adding another layer of indirection). I will say that I have "the > os" in well under 4MB (where "the os" is defined as kernel, core apps like stuff > in /bin and /sbin, and libraries like glibc in /lib; this does not include > /usr of course). Aagin you can save a fair amount on smaller systems by playing > tricks with smaller versions of libraries, but on a system with full apps like > mysql and gcc, it won't be worth it (as I think gcc completely and utterly > requires glibc). > > Toolchains are big, but they're not that big. I've seen full x86->ARM > toolchains in about 50-70MB. But that has to include all the foreign libs. > Here, those would be considered part of "the os" or "the apps", depending on > their usage, since they are needed to run stuff locally anyway. The static libs > will sometimes pose problems because they tend to be rather large, but at least > headers are usually pretty small :) 4MB!?!? with all the important apps? I have seend Linux on a floppy but they were so very limited. I think that is incredible. I will buy one of the converters and try a small install of debian, I already have a 256MB flash card. I am very suprised no one sells PC like this. All of the ones I found were cash registers or the like, no general purpose PC's. I would think this would be great for routers, firewalls, etc. High high availabilty stuff. Thanks, Matt