DVD Boot time?
I'm guessing that booting off a DVD is very slow. Are there any other
options for a read-only boot drive? Thanks. |
DVD Boot time?
Davej wrote:
I'm guessing that booting off a DVD is very slow. Are there any other options for a read-only boot drive? Thanks. A DVD might give you 5MB/sec speeds, and 130 millisecond seek speed. (time to move the head across the surface). As storage devices go, that is pretty slow. ******* In the good ole days, hard drives had a "write protect" jumper, that would allow running them such that they wouldn't accept a write. The function existed mainly on SCSI drives. It appears SAS drives may have continued the tradition, as a write protect jumper is shown here. This would be pretty fast as a boot device. And *very* expensive to set up. http://forums.seagate.com/t5/Savvio-...File/m-p/30291 I'm not sure regular Windows would like it very much, if you installed on a drive, shut down, then inserted the write protect jumper. Windows might crash, if faced with a situation that the storage subsystem reported it was read-only. It's not designed for it, without a scheme in place to accept writes. Some other OS setups would tolerate it. I have Knoppix loaded on a USB2 flash stick, and the storage is separated into two areas. The original OS image is something like a SquashFS file, and may not be writable. There is a second storage space, called "persistent store", and that holds any files that have been updated. If you delete the persistent store contents between boots, that may give you roughly the equivalent or read-only, in that you can wipe any changes made. You can also set them up, without a persistent store. I believe there are some USB distros, that run purely read-only and work as if they were a CD or DVD. And if you got yourself one of the new USB3 flash sticks, you'd be able to do better than 30MB/sec. The topic of boot time came up the other day. There are no miracles for boot time, because a significant chunk of the time is spent at BIOS level. So even if the software came "flying off the disk", you'd be looking at 40 seconds plus, as a best case. Lots of things on computers are "hurry up and wait" situations, and the BIOS can wait up to 35 seconds in the hope that a slow hard drive will report in. An OS such as SplashTop/ExpressGate is probably about as close as you'll get today, to "instant on". ExpressGate runs at the BIOS level, and by cutting out discovery time for hard drives, is able to start faster. They quote 5 seconds here. http://en.wikipedia.org/wiki/Expressgate Windows has SteadyState, which can be set up to give the appearance of being read only. As far as I know, there is an option to toss out all changes made since the last session. Such an option might see use in a public library computer, or in an Internet Cafe. http://en.wikipedia.org/wiki/SteadyState Paul |
DVD Boot time?
On Apr 12, 12:45 am, Davej wrote:
I'm guessing that booting off a DVD is very slow. Are there any other options for a read-only boot drive? Thanks. No, it's not. The system IO files and a command interpreter load quicker than you can count to three. After that it's as slow as whatever is loading. Options are limitless provided there's a level of support from the host machine's ROM/CMOS into peripheral hardware and additional system-level drivers as needed. All certainly an other- liness that wouldn't be seen as other than an obfuscating rat's nest of backassed wires and kludge, FUBAR for mainstream purposes. :) |
All times are GMT +1. The time now is 08:35 AM. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
HardwareBanter.com