What is memory pressure?

glubslyme

macrumors newbie
Original poster
Aug 30, 2012
2
0
Hello,

I've had an early 2011 15'' MBP for almost 2 years now, and it has become noticably slower. The obvious solution is to increase the RAM. However, when I go to activity monitor, whilst it states at times that 3.99GB out of 4GB are in use, the 'memory pressure' remains green and doesn't appear to be very high.

What exactly is memory pressure, and do these results indicate that a RAM increase would speed up my computer - I don't want to waste money on more RAM if it wouldn't have any real effect!

Thankyou!
 

Jambalaya

macrumors 6502a
Jun 21, 2013
686
98
UK
If you're memory pressure is green (low) then its not that which is making your machine slow. Memory is an issue if your swap usage is significant (ie memory full so OSX uses the disk which is slow). A combination of near full HDD an 4gb can make the machine sluggish

Mavericks uses up memory for example by preloading applications (ie guessing what you might want to do next based upon prior usage) so often memory appears full.

IMO your machine will run better with 8gb but it would be worth checking to see what programmes you have running which might be stalling the machine due to trying to access Internet. Arguably an SSD might make more difference than goin from 4 to 8gb ram. Depends on what you're doing
 

sjinsjca

macrumors 68020
Oct 30, 2008
2,190
511
Your machine is nearly three years old. That's pushing it for a hard disk. Your machine's behavior sounds much like that of my wife's Macbook Pro (same vintage) a couple months ago. It was just getting terribly slow. (The disk was only about 30% full, too... an over-full disk can contribute to slowness.)

I took it to the Genius Bar and they ran it through a bunch of tests but all returned successfully without an issue being spotlighted. So I shrugged and ordered a nice Seagate Momentus XT drive. It arrived, and I installed it (so easy) and restored the machine from a Time Machine backup. Cradle to grave was perhaps two or three hours.

Night and day. It runs like a scalded cat again.

This was not the first time I'd experienced "sub-clinical" hard disk issues... it's a familiar situation from my Windows days.

So I'd say: drop a hundred bucks or so and treat your faithful machine to a new hard disk.

And maybe some more RAM too. Doesn't seem like you actually need it, but it's always good to have, and cheap nowadays.
 

drew627

macrumors regular
Jun 26, 2013
189
3
I bought my MacBook Pro in 2010 and it's still running perfectly (as fast as it's ever been) under Mavericks. Did upgrade my hard drive to a hybrid drive (a Momentus XT too!) though and saw some noticeable improvement. 4GB RAM is fine and enough.
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
30,313
10,050
California
Just wondering, how is three years pushing it for a hard disk?
Good article here on hard drive lifespan. The three year point seems to be where the failure rates go up.

Excerpt:

The theory matches the reality that Backblaze experiences. The chart below shows the failure rate of drives in each quarter of their life. For the first 18 months, the failure rate hovers around 5%, then it drops for a while, and then goes up substantially at about the 3-year mark. We are not seeing that much “infant mortality”, but it does look like 3 years is the point where drives start wearing out.
From what you are saying about Activity Monitor, it does not sound like adding memory will speed things up. How full is your hard drive? They will get slower when close to full.
 

TheEnthusiast

macrumors regular
Aug 22, 2013
146
3
Interesting. I have two HDDs that have lasted me 9 years so far, and I'm sure others have had the same experience. I wouldn't generalize. Although, it does seem to be the case that drives made more recently are more prone to failure.
 

ElectricSheep

macrumors 6502
Feb 18, 2004
498
3
Wilmington, DE
That study is incomplete, and there are several ways to interpret the data thus far. Yes, at the three year mark wear-out failures start making a more significant contribution to total failure rate than random failures.

On the flip-side, if your drive has made it to three years there is a 87% chance that it will make it to four years without issues. Assuming the projections fit a linearly increasing wear-out rate (I would personally expect that the trend will have several more plateaus and sharp gains), then you can expect half of consumer-grade hard drives to last six years before giving up the ghost. It would be at that point that I agree is "pushing it" for hard drive lifespan.
 

sjinsjca

macrumors 68020
Oct 30, 2008
2,190
511
Interesting. I have two HDDs that have lasted me 9 years so far, and I'm sure others have had the same experience. I wouldn't generalize. Although, it does seem to be the case that drives made more recently are more prone to failure.
Sure. The data is stored way more densely than in a nine-year-old drive, and head flying heights and magnetic bit dimensions are in the nanometer realm now. It's really amazing that these things work at all, much less survive what we put them through in daily usage.

Besides the obvious wear and tear a laptop drive would see, there are subtler contributions to its overall longevity. Using a hard disk on an airliner is a good example: the thinner air at-altitude means lower flying heights and that much less cushion against physical collision between head and rotating platter. The quality of your AC mains supply also makes a profound difference over time. And so on. Your mileage will definitely vary, when it comes to disk-drive longevity.

----------

On the flip-side, if your drive has made it to three years there is a 87% chance that it will make it to four years without issues.
Well, see, that's the problem: OP may be seeing "issues" just as my wife's Macbook Pro's disk manifested recently. Sub-clinical, but definitely starting to worsen over time.

Replacing the drive is so cheap and so easy that it's hardly worth hesitating over once the usual first-step attempts at resolution have failed. If the new drive doesn't fix the problem then hey, you have a spare drive now.... but I'd expect OP to be as delighted as my wife is with her new drive.

This is also a fine reminder to back up your system!
 

2trout

macrumors member
Nov 2, 2013
70
3
Tucson
Get an SSD and prepare to have your mind blown.
I agree. If you're planning to keep your Mac, or PC for that matter, for quite a while yet, 'loose' a bit more $ and get yourself an SSD, the difference is night and day, really is quite amazing!
Prices of SSD's have dropped dramatically, and still are. I even installed a SSD in my garage ACER laptop running XP, the difference was amazing!
 
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