On Fri, Dec 17, 1999 at 01:51:54AM +0200, Evgeny Stambulchik wrote:
> On 15-Dec-99 Eli Marmor wrote:
>
> > As Gavrie noted, there is no difference between the technologies which
> > should cause any difference in quality. The mechanics is similar.
>
> As far as performance is considered, it's not RPM that usually matters (inspite
> of a big hype), but the amount of cache on disk. Until recently (1-2 years), the
> maximum cache on IDE disks was 128KB, while about each SCSI disk had
> 0.5MB.
This is not exactly the truth ... Check out reviews and some real
numbers about Quanttum Fireball SE . It was UDMA/33 IDE drive whihc
had only 128K cache (not a long time ago - two years) and it performed
better than its WD or even IBM counterparts , which had 4-times bigger
cache - 512K . I'm not going to say that cahce isn't playing any role
in all that, it actually does, but when we're speaking about the real
performance, we're speaking about continuous transfers of VERY big
files - i.e. we're measuring the real read/write speed of drive, when it
physically accesses the plates and transfers tthe data from/to it .
The cache is important for relatively small files , which happen to be
PHYSICALLY close to each other . For example, the cache controller of
one of Qunatum drives (I think it was Bigfoot) makes caching based on
very simple criteria - it analyzes which physical sectors of disk are
mostly used for some period of time and caches data from these sectors
any time it can, but be honest, nowadays even 2MB cache isn't enough
to cache all files being used, not to mention that *real* OS sometimes
swaps data, it's multiuser and multitasking system and almost at any
time there is no cache hit :( .
Just to show you how small 2MB cache is, think about this - minimal
amount of data which can be read/written by HDD controller is 512bytes
(size of one sector) and how many such sectors we have in 2MB ?
2048, isn't it ?
So, how much sectors you can cache (you - hdd cache controller) in
vast majority of cases depends on amount of small files frequently
used by system (ideal variant) OR how many files are happen to be
close enough each to other on hard disk . MOst of standalone test
programs show that in case you're using somethine like 20-30 small
files (less than 4-8K in size) you will have a cache hit , but if
you're using "just" 20% big files (more than 100K approx) you will
see that number of cache hits decreases by 40-50% .
So, for real work , or for SERVER or for HIGH-PERFORMANCE workstation
what is more important is the RPM , which means HIGHER linear speed no
matter size of files being used most of time .
> > Once I was puzzled about the difference in pricing, asked many people,
> > and got the following answer: It's a matter of marketing. If all the
> > disks will be expensive, no home users will buy them. If all the disks
> > will be cheap, you will lose the big money (corporations and other
> > rich customers who are willing to pay thousands for one disk). The way
> > to eat the cake and still have it, is by selling cheap disks AND
> > expensive disks. But how can you force the rich customers to buy the
> > expensive disks? By using a low quality manufacturing for the cheap
> > disks. To help people know what disk should each buy, all the IDE
> > disks are manufactured in low quality, and all the SCSI disks in high
> > quality.
>
> Well, it's an chicken and egg problem: to manufacture something with a higher
> quality, one does need to invest more, even if the underlying technology is the
> same.
What does make adifference in IDE drives for your opinion ? And I know
what - the engine . Look at Quantum Fireball CX drive and which engine
it uses and at Quantum Fireeball CR - and feel the difference .
There are also some differences in mechanics but they're minor .
> Alas, not all. I also used to think so, and it struck me already twice. I do
> suspect, though, that at least in one of the two cases it was just a plain lie
> of the Israeli reseller (Mediatek) - when it came to replacement; but does it
> help? :^). Notice that nowadays many HD resellers stamp on disks the _start_ of
> the warranty period, not the _end_, and, after 2-3 years have lasted, it's quite
> difficult to prove that it was promised to have a 5 year warranty.
Here I agree with you. MOST of Israeli importers are *lying* to their
customers in 70% of cases or trying to make money from nothing .
Do you know why for example Official Distributor of WDC (I'm talking
about EIM now) REFUSES to replace WD drives in the warranty period
not purchased DIRECTLY from them ? This is violation of their
agreement with WDC Germany but since there is NO law in Israel which
protects you from this , they will piss on you and will not replace
the drive until you'll begin your own revolution against them and
write a bunch of e-mails to the Germany (WDC Germany) asking from them
to revoke the rights from EIM . I'm talking seriously, from my
friend's experince who were trying to replace his almost new drive
which he purchased from some small computer shop which got bankrupt in
three months after that . ANd the drive is dead in 6-month perioed by
the way , and still EIM and Waitek didn't want to replace it .
Mike.
--
----------
Computers are like air conditioners. Both stop working if you open windows.
-- Adam Heath
----------
=================================================================
To unsubscribe, send mail to [EMAIL PROTECTED] with
the word "unsubscribe" in the message body, e.g., run the command
echo unsubscribe | mail [EMAIL PROTECTED]
