A question about solid state drives

[a]

What's the difference between:

installing your OS and all your programs on the SSD

and:

using the SSD as a cache drive?

If both options give you equal performance in terms of speed what
would be the advantage of going with the cache drive option?

Jon

 

[John Doe]

Just be sure to get a current SDD drive. I think there were
problems with early models. Maybe avoid brands that have a bad
reputation. Pay attention to how they treated customers who needed
to return a drive. I had problems with OCZ SDD drives. And use it
as your drive C, with your OS (Windows) and programs.

Also... Look to see if they have mean time between failure (MTBF)
ratings. At first, they claimed over 1 million hours. Apparently
that was a marketing lie.

 

[Paul]

What's the difference between:

installing your OS and all your programs on the SSD

and:

using the SSD as a cache drive?

If both options give you equal performance in terms of speed what
would be the advantage of going with the cache drive option?

Jon

When you have the facilities to run an SSD as a cache, it "remembers"
a fraction of a larger hard drive.

Say, for example, you have a 20GB SSD and a 1TB hard drive. The
ratio between those two, is fifty to one. The SSD then, can only
"remember" 2% of the entire hard drive. And speed up, 2% of the
accesses. (This would be a read-cache.)

If the caching is intelligent, or, if you make reference to mostly
OS files on a given day, perhaps the SSD used as a cache, will end
up holding mainly OS files. And then, on the next boot, assuming
the cache concept works during the boot phase, the boot will be faster.

*******

Now, say instead, you did not use the cache concept. You used the
20GB drive as C: instead, and installed the OS. Now, any file put
on the 20GB drive is fast. But if you had any "irrelevant" files
on there, they're "wasting" storage space on your fast device.

So in balance, the cache concept allows the most recently used
things to be cached. And if the cache software is intelligent,
maybe most of what is cached is OS files, and OS related things
go faster. But if you compared benchmark performance, the
cache can never be exactly as fast as using the 20GB drive directly
as C:.

But if you used a 20GB drive as C:, you'd rapidly run out of space.
My Windows 7 laptop, uses at least 26GB as of SP1, so I couldn't
even fit all of Windows 7 on there. In which case, I might have no
option but to use some caching scheme. (Or, just install to the
1TB, and forget about the SSD entirely...)

Using a drive as a cache, in terms of the "wear" properties,
really depends on what the LRU (least recently used) policy is
doing. Say the cache is "dumb", you view a 9GB movie for a couple
hours, and in the process, the cache copies the movie to the SSD.
Now, 9GB of other files, are purged to make way for the movie.
Next, say you reboot. On the reboot, none of the tiny OS files
are on the SSD, because the 9GB of flushing removed them. So the
next boot seems slow by comparison. Until the movie is flushed from
the cache, and replaced by OS files. So as to how well the scheme
works, you need to know a lot about the caching principle, whether
all files are treated generically, or whether OS files take
priority somehow.

The idea has pros & cons, and the devil is in the detail.

Paul

 

[Flasherly]

What's the difference between:

installing your OS and all your programs on the SSD

and:

using the SSD as a cache drive?

If both options give you equal performance in terms of speed what
would be the advantage of going with the cache drive option?

Jon

The OS is only 600meg or so if XP. Clean install. Add some stuff for
programs elsewhere, maybe the OS will swell up to 1.5G, matter of
efficiency, dependencies, and programing style. Will they actually
sell a 2G, 5G, a 10G or 20G SSD for a snowball's chance in
hell? . . .Who knows with 8G of DDR3 for $19. So, what's the
difference in a 5G SDD going to be, for some, if all the programs, and
OS, will go on it? Cache, anyway, is for clouds, massive distribution
system, proprietary and in-house applications. Not desktops. Went
out with abstract program layering of compressed drives. (Stacker,
which MS stole, got sued, got slick and turned around and bought it to
release as Doublespace for 95 & 98 Winderz. Past tense. History.)
The Prophet Murphy said there will days like this.

 

[Yousuf Khan]

What's the difference between:

installing your OS and all your programs on the SSD

and:

using the SSD as a cache drive?

If both options give you equal performance in terms of speed what
would be the advantage of going with the cache drive option?

Jon

The caching concept is sort of a compromise made for people who don't
have a large enough SSD. If you have a large enough SSD to hold your
entire OS, then don't bother with using it as a cache. For example, if
you have a 64GB SSD or smaller, you probably don't really have enough to
hold Windows 7 and all of the applications you have, so using it as a
cache is a good option. The cache drive might be big enough to cache
everything you need to speed up the boot process, so it would cache only
the files needed for that, and then some other common files, like your
web browser, or email client, etc.

If you have a 120GB or larger drive, you might be able to hold your
entire OS and applications as a drive on its own. You'll find that the
proper SSD drive is given a higher Windows Experience Index number than
a caching SSD drive is. I've found that WEI is a pretty good indication
of real-world daily performance. Full SSD solution are usually given
scores of between 7.0 and 7.9 on the WEI index. You might be lucky to
get up into the 7's with a caching SSD. That's because once the cache
runs out, the reads & writes have to go back the regular HDD that the
cache drive is fronting for.

Yousuf Khan

 

[a]

When you have the facilities to run an SSD as a cache, it "remembers"
a fraction of a larger hard drive.

Say, for example, you have a 20GB SSD and a 1TB hard drive. The
ratio between those two, is fifty to one. The SSD then, can only
"remember" 2% of the entire hard drive. And speed up, 2% of the
accesses. (This would be a read-cache.)

If the caching is intelligent, or, if you make reference to mostly
OS files on a given day, perhaps the SSD used as a cache, will end
up holding mainly OS files. And then, on the next boot, assuming
the cache concept works during the boot phase, the boot will be faster.

*******

Now, say instead, you did not use the cache concept. You used the
20GB drive as C: instead, and installed the OS. Now, any file put
on the 20GB drive is fast. But if you had any "irrelevant" files
on there, they're "wasting" storage space on your fast device.

So in balance, the cache concept allows the most recently used
things to be cached. And if the cache software is intelligent,
maybe most of what is cached is OS files, and OS related things
go faster. But if you compared benchmark performance, the
cache can never be exactly as fast as using the 20GB drive directly
as C:.

But if you used a 20GB drive as C:, you'd rapidly run out of space.
My Windows 7 laptop, uses at least 26GB as of SP1, so I couldn't
even fit all of Windows 7 on there. In which case, I might have no
option but to use some caching scheme. (Or, just install to the
1TB, and forget about the SSD entirely...)

Using a drive as a cache, in terms of the "wear" properties,
really depends on what the LRU (least recently used) policy is
doing. Say the cache is "dumb", you view a 9GB movie for a couple
hours, and in the process, the cache copies the movie to the SSD.
Now, 9GB of other files, are purged to make way for the movie.
Next, say you reboot. On the reboot, none of the tiny OS files
are on the SSD, because the 9GB of flushing removed them. So the
next boot seems slow by comparison. Until the movie is flushed from
the cache, and replaced by OS files. So as to how well the scheme
works, you need to know a lot about the caching principle, whether
all files are treated generically, or whether OS files take
priority somehow.

The idea has pros & cons, and the devil is in the detail.

Paul

Do you know if the software allows you to manually select which
programs you want to remain in the cache? In other words say "don't
allow these programs to be purged from the cache". I haven't seen a
feature like this mentioned while reading about SSD drives. That would
seem to be the solution for the 9 GB movie scenario you described.

thanks to all who answered

Jon

 

[Bug Dout]

You will quickly run out of space if you run both the OS and programs
on the SSD.

How do you know that? You don't know. I have a netbook with a single
80GB SSD and dual-boot Win 7 and Ubuntu...every fits and works just
fine. I have a Win7x64 desktop with a 120GB SSD and the OS and programs
are all on there with plenty of room to spare.

I think that the expense of
having several large SSD's would be cost prohibitive. HD's are bad
enough expense wise, SSD are worse.

You're a ****ing idiot, quit posting shit. HD's are dirt cheap. SSDs are
more expensive but since when is the OP asking about "several large"
ones? Hangup your dialin connection and go back to watching Jerry
Springer. Maybe your cousin is on today.

 

[Paul]

Do you know if the software allows you to manually select which
programs you want to remain in the cache? In other words say "don't
allow these programs to be purged from the cache". I haven't seen a
feature like this mentioned while reading about SSD drives. That would
seem to be the solution for the 9 GB movie scenario you described.

thanks to all who answered

Jon

You do realize, there is more than one of these cache solutions around.

I can't guess at the one you're using

Paul

 

[John Doe]

How do you know that?

lol

I'm so glad you asked the obvious.

Maybe he thinks that multimedia is part of "programs".

You might need to keep an eye on certain large data or unnecessary
installed programs. That's never been a problem for me. An SDD is
like a huge RAM drive, just what I always wanted, ever since 4 MB
was a lot of RAM.

 

[Charlie Hoffpauir]

Because I have a much smaller SSD. I would not spend the money for a
large 80GB SSD because that does not add any speed and I am guessing
that you have not priced sata3HD lately. You also have a foul mouth.

Well, you're just wrong about an SSD not adding speed. I bought one,
and tested several different setups back when I was still using Win
Vista. A 7200 RPM sata drive; 2 7200 RPM sata drives in RAID-0 config;
and SSD; all tested using Win Vista and all my programs installed with
the test drive(s) set up as C. The RAID-0 config was about 50% faster
than the single drive alone, and the SSD about 50 % faster than the
RAID setup. So now I have all the programs and OS on the SSD, and all
the data on the RAID-0.

 

[John Doe]

If shopping for an SDD drive...

Go to a website like Newegg and arrange reviews by "ownership
length". Probably the most important concern is long-term
reliability.

 

[John Doe]

Or... Buy an SDD drive that is larger than you need, and hope that
their wear-leveling program works like it's supposed to.

 

[John Doe]

Or... Buy an SDD drive that is the appropriate size for your
needs, but don't expect it to last as long as most hardware lasts.

I might go for a 64 GB drive (shopping is fun). Having to replace
an SDD drive isn't such a big deal, since the technology will
probably continue to rapidly improve. That is already cheaper than
the 32 GB drive that I started with (and apparently twice failed).
I would expect to use about half of the 64 GB.

When I went back to my Raptor, I did notice some sluggishness.

 

[Yousuf Khan]

Well, you're just wrong about an SSD not adding speed. I bought one,
and tested several different setups back when I was still using Win
Vista. A 7200 RPM sata drive; 2 7200 RPM sata drives in RAID-0 config;
and SSD; all tested using Win Vista and all my programs installed with
the test drive(s) set up as C. The RAID-0 config was about 50% faster
than the single drive alone, and the SSD about 50 % faster than the
RAID setup. So now I have all the programs and OS on the SSD, and all
the data on the RAID-0.

You better read Rick's quote again, he's not saying that the SSD doesn't
add any speed over a hard drive, he's saying a larger SSD doesn't add
any speed over a smaller SSD. That may be right, or it may be only
slightly wrong, but it's not totally wrong.

Yousuf Khan