8mb cache?

[Jay]

just ordered a matrox ultra 133 80Gb drive with 8Mb cache, wants the
performance gain with the increased cache?

 

[Rod Speed]

just ordered a matrox ultra 133 80Gb drive with 8Mb cache,
maxtor.

wants the performance gain with the increased cache?

I doubt you'd be able to pick it in a proper double blind trial
with not being allowed to use a benchmark or diagnostic.

The benefit even with a benchmark varys with the work being done.

 

[Arno Wagner]

just ordered a matrox ultra 133 80Gb drive with 8Mb cache, wants the
performance gain with the increased cache?

Without OS buffer-cache (think DOS): considerably.
With OS buffer-cache: Almost nothing. Linux, e.g. on a 1GB system
uses routinely several 100MB for cache and buffer, so 8MB do
not really have any impact.

Arno

 

[Folkert Rienstra]

Without OS buffer-cache (think DOS): considerably.

Actually, almost none. And even DOS has cacheing (smartdrv).

 

[Papa]

So do you think the 8MB cache idea is mostly a marketing scheme, and will
the 2 MB cached HDs become obsolete? Looks like lots of HD manufacturers are
selling HDs with the 8MB cache these days. Thanks for your response.

 

[Eric Gisin]

If 256Mb costs $5, then 64Mb (8MB) is probably $2. Why use anything smaller?

PS, anyone know of a site that charts dram spot prices?

| So do you think the 8MB cache idea is mostly a marketing scheme, and will
| the 2 MB cached HDs become obsolete? Looks like lots of HD manufacturers are
| selling HDs with the 8MB cache these days. Thanks for your response.
|

 

[Rod Speed]

So do you think the 8MB cache idea is mostly a marketing scheme,

Yes, tho like with a lot of that sort of thing, the extra cost is
minimal now so the drive might as well have the bigger cache.

and will the 2 MB cached HDs become obsolete?

Depends on what you mean by obsolete. Not the sense that they
need to be discarded. Yes in the sense that you will likely see not
too many drive manufacturers bother to supply them anymore.

Looks like lots of HD manufacturers are
selling HDs with the 8MB cache these days.

Basically because the extra cost is peanuts.

 

[Rod Speed]

If 256Mb costs $5, then 64Mb (8MB) is probably $2. Why use anything smaller?

Particularly when there are plenty of stupid consumers
who insist on an 8MB cache, even if they wouldnt be
able to pick it in a proper double blind trial.

 

[Lil' Dave]

Let's put it this way, when WD started the 8MB cache HD thing, I bit
hook-line-sinker. Also had the same identical drive in 2MB cache version
(30GB). Could find not other physical variation between the two HDs at the
WD website. Did an image copy from the 2MB version to the 8MB version. I
did not benchmark either. Removed the 2MB version from the PC and put the
8MB version in its place. From my own usage, I could see no apparent
increase in speed in any way I used the 8MB version. It proves nothing,
except that in my case, I perceived nothing changed. Take it or leave it
with a grain of salt.
Dave

 

[Papa]

Thanks, Dave. That's been my experience too, and I jumped on the 8MB cache
bandwagon also - but it performs at least as good for my applications
(including some fairly demanding games) as the 2MB cache drives, and the
price was right (below $1 per gigabyte and still dropping). So I really
can't complain.

 

[_]

just ordered a matrox ultra 133 80Gb drive with 8Mb cache, wants the
performance gain with the increased cache?

There's probably a measurable difference in the lab, but I'd expect
the real world improvement is non existent.

I'd suspect the ram chip manufacturer simply improved it's product
(2M>8M) for the same price.

I think the biggest difference is you generally get a three year
warranty on the 8M models

 

[Folkert Rienstra]

There's probably a measurable difference in the lab, but I'd expect
the real world improvement is non existent.

I'd suspect the ram chip manufacturer simply improved it's product
(2M>8M) for the same price.

As with everything, the 8M chip will be the next high volume chip and
the 2M chip will get more expensive to produce and finally be obsoleted.

 

[Folkert Rienstra]

So do you think the 8MB cache idea is mostly a marketing scheme,

No, not at all.
If your application benefits from cache it will benefit longer from that
cache when it is bigger. In any cache, some data will be kicked sooner or
later to make place for newer data. The bigger the cache, the longer the
data can stay (more segments). Or with the same number of segments,
the bigger the individual cache segments can be.

and will the 2 MB cached HDs become obsolete?

When 2MB cache chips become more expensive than 8MB chips, very likely.

 

[Alexander Grigoriev]

There is a case when it shows: multichannel playback. 8MB buffer allows to
read-ahead more (disk) tracks, so when multiple files are read in parallel,
there is less need to seek. With 2MB, number of channels that can be read in
parallel, is considerably less. When number of channels exceeds number of
disk tracks that can be kept in the read-ahead, number of seeks jumps
considerably.

 

[Alexander Grigoriev]

It seems, it already is. Most produced SDRAM chip seems to be at least 32MB.

 

[Arno Wagner]

There is a case when it shows: multichannel playback. 8MB buffer allows to
read-ahead more (disk) tracks, so when multiple files are read in parallel,
there is less need to seek. With 2MB, number of channels that can be read in
parallel, is considerably less. When number of channels exceeds number of
disk tracks that can be kept in the read-ahead, number of seeks jumps
considerably.

Actually a modern OS does its own read-ahead, so this advantage
vanished almost completely as well.

Arno

 

[Papa]

Thanks very much. Your response was very informative. Appreciated.

No, not at all.
If your application benefits from cache it will benefit longer from that
cache when it is bigger. In any cache, some data will be kicked sooner or
later to make place for newer data. The bigger the cache, the longer the
data can stay (more segments). Or with the same number of segments,
the bigger the individual cache segments can be.


When 2MB cache chips become more expensive than 8MB chips, very likely.

<snip>

 

[Papa]

Thank you, everyone. This thread could be used as a guideline for how a
thread can accomplish good communications and intelligent responses.

 

[Mr. Grinch]

All other performance optimizations aside (OS, application) the biggest
difference will be seen only with certain types of applications.

Something that does sequential read / writes of a large file for example
will see no benefit. The file will never fit in the memory of the cache,
and a sequential operation there is no reason to ever re-read or write the
same portion of the file, you just keep going to the end. This would be
like a backup or restore or disk image operation. The bottle neck is still
the physical drive platters a 2mb vs 8mb cache will show no difference.

On the other hand, if you have a situation where the same sectors of the
disk are being re-read and re-written constantly, the 8mb MIGHT be faster.
I say might because if the data is less than 2 mb, then both caches will
perform the same. But if it's significantly bigger, then you'll see the
8mb version pull ahead. Examples that would involve constant access to the
same sectors would be a file system that constantly access the FAT or
equivalent, for example, a database, or a swap file / page file.

The thing to keep in mind is we don't all run the same apps and so some
people will see a benefit and others won't. Some people could see a
benefit but only if they've configured the app to use that drive (ie - swap
file).

 

[Sam Williams]

Sure, but quite a bit of the time the drive is way ahead
thruput capability wise anyway, so thats rather theoretical.

Actually a modern OS does its own read-ahead,

But cant know the physical geometry detail on whats
in the current track and can be preloaded for close
to zero overhead if nothing else is pending.

so this advantage vanished almost completely as well.

Nope, if anything that particular problem has got worse now
that the OS isnt working in terms of physical cylinders heads etc.