Hi
05 Feb 2001, Clarence Verge <[EMAIL PROTECTED]> wrote:
>> Delayed write is simply that writes are not done immediately, but
>> can be held back a little time. (usually 2 seconds)
>>
>> The only thing which can happen is, that the computer crashes/looses
>> power before it has written the data ... but this would not lead to
>> corrupted files, but to not updated files.
CV> Anything that could cause the DIRS not to be updated and the FATS not
CV> to be re-written promptly can, and will, lead to serious damage if
CV> these jobs get forgotten or interrupted -
you don't see to understand the concept ...
if you write something to disk, FAT and DIRS are updated IMHO immediately.
(independant of delayed writes !)
With delayed write, some writes are held back for a small time.
And after that time (or even before, if system is idle) the hled back
writes are written, and immediately dirs and FAT updated.
So the only difference is, that if the computer crashes while there are
held back writes, you will lose these updates.
The chances for system corruption are equally high with delayed writes than
without them. (system corruption occurs when updating fat/dirs) and there
is not more time used for these critical action with delayed write !
CV> Circumstantial evidence has linked delayed writing in general and
CV> Smartdrv in particular to corrupted and cross-linked files.
I have used smartdrv for years, and have never had any problems.
It's also possible that these are hardware glitches.
But sure it's possible that smartdrv has some nasty bugs, that show only in
special configurations ...
BUT _delayed writes_ for itself is not evil.
Linux kernel uses it, and I know many linux computers with uptimes > 1
year.
The problem is the EXTREMELY crappy FAT filesystem !!!
It was intended for floppies. (and was fully suitable for that purpose !)
BUT it was the worst sollution from M$ to use FAT for HDDs.
(and now they made an equally stupid move, with extending FAT to 32bits,
to support even larger HDDs ...)
PS: You can set a sync attribute in ext2fs, which disables delayed writes
for that file ... but it is rarely used ...
(only use I have found today, is a logging system at university, which logs
keypresses and timestamps during exams ... if there should be any problems,
you can review this log, and will see exactly the situation before crash.
(there have never been any since now, but university wanted to be sure ;)
CV> http://www.google.com/search?q=cache:www.sosoft.com/fod/fod_703.htm+N
CV> orton+Ncache
I never sayd smartdrv is great ;)
You can surely use other caches in DOS, and this is a wise decision.
I simply said that you sould not speak about delayed writes in general, and
mean the smartdrv implementation ...
The concept is widely used ... and the example with linux boxes running for
years under heavy use as http/sql/... server and using write delay.
CV> - Clarence Verge
CU, Ricsi
--
|~)o _ _o Richard Menedetter <[EMAIL PROTECTED]> {ICQ: 7659421} (PGP)
|~\|(__\| -=> Minds, like parachutes, only work when they are open <=-
