Op 3-11-2011 21:05, Jack schreef: > Absolutely UNBELIEVABLE to me that FLASH devices are used AT ALL in > hard-disk replacements!! Last I knew, FLASH devices are writeable > only about 10,000 times. That is a LOW number of writes for disks > if one considers DIRECTORY updates that any DOS system will do VERY > often!! Even using an old "Write Back" (delayed-write) cache like > SMARTDRV, or Norton NCACHE2, I doubt that writes could be minimized > enough to make limited-life FLASH device "disks" worth their cost!!
It's individual cells that are only rewriteable a limited number of times (might be 10K indeed as you mention). A nice little technology called Wear Leveling spreads out the writes pretty well (though quite a lot of static data might mean this won't go that well). For all things besides cost and data recovery, a Solid State Disk is well worthwile (reduced access times, no noise, hardly any heat, etc). It acts same as a conventional harddisk, though the technology of NAND flash and controllers has its peculiarities. Disk-On-Module and simple USB flash drives are a whole different thing, they're quite basic (single-channel for example). The exception is some fancy expensive USB3.0 flash sticks which can do sequential reads and writes over 100MB per second. > If the DOM products have normal RAM chips (not FLASH types) and are > as "compatible" with IDE controllers as everyone seems to say, then > my next "hard disk" purchase shall be another actual HARD disk or a > DOM module if necessary, NOT any sort of FLASH type! Allows me to > stay with UIDE, which may not use delayed-writes but takes only 944 > bytes of upper/DOS memory [plus a bit of "invisible" HMA] and gives > me up to 4-GB caches! Try to get even 1-GB using any "Write Back" > cache, and I have 5 words for you: "Good LUCK -- You'll NEED IT"!! Best of both worlds would be a Seagate Momentus XT harddisk (not currently though, harddisk plants are underwater in thailand, causing huge price increases) as it's a conventional harddisk with a small amount of flash memory as buffer. SSDs are worthwile but a lot of investigation is needed so people look beyond best-case scenario's regarding sequential speed and disregard quality/reliability (hello OCZ/SandForce and ancient JMicron controllers) and features (buffers, powerloss, TRIM, SCSI unmap command, other ways of garbage collection) I tend to run DOS nowadays from either inside an emulator, or from a USB Flash drive. No access to my SSD in that last case, most drives nowadays are converted to the Windows world (100% capacity of drive as NTFS for Windows). ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
