SSD: How much space for cache?

[Craig Coope]

Hi,

I'm about to set up an HDD and an SSD with Intel Smart Response
Technology. My SSD is 60Gig and I only bought it for the ISRT purpose.

My question is: Do I need to allocate the whole SSD for the cache? Or
would it be a waste of 60gig?

Should I allocated 20gig and use the remaining for other apps etc?

Thanks.

 

[John Doe]

Hi,
Lo,

I'm about to set up an HDD and an SSD with Intel Smart Response
Technology. My SSD is 60Gig and I only bought it for the ISRT
purpose.

My question is: Do I need to allocate the whole SSD for the
cache?

I guess you're referencing something about that Intel technology.

Or would it be a waste of 60gig?

That is very difficult to tell without knowing something about
your intended application and that Intel technology.
--

 

[John Doe]

Since you apparently have no other use for it, I think the logical
answer is "No" it's not a waste.

Whatever that stuff is, it must be exciting.

 

[Paul]

Since you apparently have no other use for it, I think the logical
answer is "No" it's not a waste.

Whatever that stuff is, it must be exciting.

There is an article here on it, but like a similar
technology announced a while back, it isn't explained
in technical detail. They keep referring to RAID 0,
which has a specific meaning (striped). I doubt the
thing is striped, as that would make no sense. If it's
a cache, it has elements of RAID 1 in it (mirror, where
the first device responding, is the one whose data is used).

http://www.pcper.com/reviews/Storag...hing-Z68-Tested/Boot-Option-ROM-Boot-Performa

If you were caching the boot drive, it also isn't clear what
criteria it uses. For example, say I set up a 20GB cache,
then while working on a 10GB movie file of some sort, cause
the cache to be flushed to disk. Would the next boot be
accelerated ? Does the driver know the difference between
a big-ass data file, and OS files ?

Perhaps some other article, dwells on the practical details.

This one has a few more details. Intel limits
the size of the cache to 64GB, because at that point,
it just makes more sense to drop the cache and use
the SSD alone, for its SSD performance characteristics.
(Being careful to do frequent backups, just in case.)

http://www.anandtech.com/print/4329

"The Downside: Consistency

Initially it's very easy to get excited about Intel's SRT. If
you only run a handful of applications, you'll likely get performance
similar to that of a standalone SSD without all of the cost and size
limitations.

Unfortunately, at least when paired with Intel's SSD 311, it doesn't
take much to kick some of that data out of the cache."

Being a cache, it's subject to evictions. Eviction is more likely,
if you do a lot of different stuff during the day. If you just
install the OS on the 60GB drive, then the performance will be
(relatively) consistent. Then, it is a matter of whether there
is TRIM, whether the drive has lots of spare space, as to how
well it maintains transfer speed.

Apparently, if the whole thing isn't allocated, the remaining
space can have its own drive letter.

*******

There was a company, that made a $50 adapter, where you fitted
an SSD and a hard drive, and it did something similar. The Intel
scheme seems to work better. For the added nuisance value, I'd probably
just make that SSD the boot drive and not bother with the notion
of caching.

Paul

 

[Craig Coope]

There is an article here on it, but like a similar
technology announced a while back, it isn't explained
in technical detail. They keep referring to RAID 0,
which has a specific meaning (striped). I doubt the
thing is striped, as that would make no sense. If it's
a cache, it has elements of RAID 1 in it (mirror, where
the first device responding, is the one whose data is used).

http://www.pcper.com/reviews/Storag...hing-Z68-Tested/Boot-Option-ROM-Boot-Performa

If you were caching the boot drive, it also isn't clear what
criteria it uses. For example, say I set up a 20GB cache,
then while working on a 10GB movie file of some sort, cause
the cache to be flushed to disk. Would the next boot be
accelerated ? Does the driver know the difference between
a big-ass data file, and OS files ?

Perhaps some other article, dwells on the practical details.

This one has a few more details. Intel limits
the size of the cache to 64GB, because at that point,
it just makes more sense to drop the cache and use
the SSD alone, for its SSD performance characteristics.
(Being careful to do frequent backups, just in case.)

http://www.anandtech.com/print/4329

"The Downside: Consistency

Initially it's very easy to get excited about Intel's SRT. If
you only run a handful of applications, you'll likely get performance
similar to that of a standalone SSD without all of the cost and size
limitations.

Unfortunately, at least when paired with Intel's SSD 311, it doesn't
take much to kick some of that data out of the cache."

Being a cache, it's subject to evictions. Eviction is more likely,
if you do a lot of different stuff during the day. If you just
install the OS on the 60GB drive, then the performance will be
(relatively) consistent. Then, it is a matter of whether there
is TRIM, whether the drive has lots of spare space, as to how
well it maintains transfer speed.

Apparently, if the whole thing isn't allocated, the remaining
space can have its own drive letter.

*******

There was a company, that made a $50 adapter, where you fitted
an SSD and a hard drive, and it did something similar. The Intel
scheme seems to work better. For the added nuisance value, I'd probably
just make that SSD the boot drive and not bother with the notion
of caching.

Paul

Hmmm... I'm about to go to bed and when I wake up I should have all my
parts ready for the build and I'm still not sure what I want to do.
I'll probably use it all as the cache. If I don't like it I can always
start again I guess.

 

[John Doe]

John Doe wrote:
....


There is an article here on it, but like a similar
technology announced a while back, it isn't explained
in technical detail. They keep referring to RAID 0,
which has a specific meaning (striped). I doubt the
thing is striped, as that would make no sense. If it's
a cache, it has elements of RAID 1 in it (mirror, where
the first device responding, is the one whose data is used).

http://www.pcper.com/reviews/Storag...hing-Z68-Tested/Boot-Option-ROM-Boot-Performa

If you were caching the boot drive, it also isn't clear what
criteria it uses. For example, say I set up a 20GB cache,
then while working on a 10GB movie file of some sort, cause
the cache to be flushed to disk. Would the next boot be
accelerated ? Does the driver know the difference between
a big-ass data file, and OS files ?

Perhaps some other article, dwells on the practical details.

This one has a few more details. Intel limits
the size of the cache to 64GB, because at that point,
it just makes more sense to drop the cache and use
the SSD alone, for its SSD performance characteristics.
(Being careful to do frequent backups, just in case.)

http://www.anandtech.com/print/4329

"The Downside: Consistency

Initially it's very easy to get excited about Intel's SRT. If
you only run a handful of applications, you'll likely get performance
similar to that of a standalone SSD without all of the cost and size
limitations.

Unfortunately, at least when paired with Intel's SSD 311, it doesn't
take much to kick some of that data out of the cache."

Being a cache, it's subject to evictions. Eviction is more likely,
if you do a lot of different stuff during the day. If you just
install the OS on the 60GB drive, then the performance will be
(relatively) consistent. Then, it is a matter of whether there
is TRIM, whether the drive has lots of spare space, as to how
well it maintains transfer speed.

Apparently, if the whole thing isn't allocated, the remaining
space can have its own drive letter.

*******

There was a company, that made a $50 adapter, where you fitted
an SSD and a hard drive, and it did something similar. The Intel
scheme seems to work better. For the added nuisance value, I'd
probably just make that SSD the boot drive and not bother with
the notion of caching.

That crossed my mind when trying to interpret what the original
post was supposed to be about, that he is talking about general PC
use.

The SSD is best for reading. Using it as a cache means all of your
program data has to be rewritten at least once during the day.
Sounds counterproductive. I would not bother with it.

If I were the original poster, I would use my new SSD for the boot
drive (including programs), and use a big conventional drive for
data (including copies of the SSD). Been working great for years
here. And he should remember to keep a backup copy of any
important data to removable media.
--

 

[Loren Pechtel]

I have not practical knowledge to offer, but I've seen recommendations
to not use a scratch drive on an SSD. Just load up on *real*
memory--RAM--and spare your SSD the churning that swap drives must endure.

Yeah--if you're going to the cost of a SSD, go for gobs of ram.