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Slow Mid-2011 27" iMac

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fmalloy

macrumors 6502
Original poster
Nov 5, 2007
406
248
Mid-2011 iMac performance is very slow - booting (takes forever to get to the desktop) opening/closing/switching apps, loading photos in the Photos app, and switching users is particularly painful.

CPU shows low loads (10% or less). Upgraded the RAM to 12MB; memory usage is low, yet still everything runs slow. I do seem to see more disk transfers going on in the Process app than I would expect. Ran Disk First Aid and it's clean. 2GB of disk is available, so it's not full.

I had an external hard drive for Time Machine backups that went south and will no longer spin up; I disconnected that from USB and saw some improvements in the disk transfers, but overall performance is still slower than expected.

The last resort I'm doing is to erase the drive and reinstall the OS and backup data. Anything else to try before I give up and buy a new iMac?
 
redheeler said:
The cause of the slowness is most likely the original hard drive. An SSD upgrade will make it feel like new.
Click to expand...
Thanks for the reply!

I can see how an SSD would be faster, but the thing is - the disk was certainly fast enough when I first bought it, and for a few years after that. Could the many OS revisions put *that* much more demands on the disk and make the whole system this slow?

It's a 1TB disk, and I would think a 1TB SSD will be pretty $$$, plus I have no idea what kind to get and how easy it is to install. In addition, the SuperDrive also failed so I wonder how much more money should be put into it, also considering it won't support Mojave...
 
fmalloy said:
Thanks for the reply!

I can see how an SSD would be faster, but the thing is - the disk was certainly fast enough when I first bought it, and for a few years after that. Could the many OS revisions put *that* much more demands on the disk and make the whole system this slow?

It's a 1TB disk, and I would think a 1TB SSD will be pretty $$$, plus I have no idea what kind to get and how easy it is to install. In addition, the SuperDrive also failed so I wonder how much more money should be put into it, also considering it won't support Mojave...
Click to expand...
You don't have to replace the original 1 TB hard drive completely. In fact, you can replace the failed SuperDrive with an SSD using something like this or this and still use the 1 TB mechanical drive for file storage. The Data Doubler can use the optical drive's SATA connection, which makes it easier to install but limits the SSD to SATA II speeds (still a big improvement over the speed of the original mechanical drive).
 
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Reactions: keysofanxiety
First, 2GB free? That is full. Too full. Give it 10% and see if the performance is acceptable to you.

Second, I had that model before it died a Radeon death. SSD definitely made it perform to my satisfaction. I replaced the main drive with a Samsung 950 Pro. Newer OSX is not optimized for IO performance in my experience. The fact they still offer spinners blows my mind.
 
keysofanxiety said:
SSD is a definite, the newer OSs don’t play well with spinning drives.
Click to expand...
Thank you. I do understand that data is accessed differently in an SSD, and that they optimized recent OSes for SSD access. And Apple says they don't practice planned obsolescence... :mad:

I reviewed a couple of videos on how to replace/add an SSD to the 2011 iMac and - sorry - for me too many steps and things to take apart and put back together for a computer that won't even take the latest OS. Sure looks to me Apple said "how can we make it as difficult as possible to replace the hard drive, which, next to RAM, is the most common thing to replace?"

Well, they achieved their mission.
[doublepost=1539031554][/doublepost]
BorderingOn said:
First, 2GB free? That is full. Too full. Give it 10% and see if the performance is acceptable to you.
Click to expand...
Two freaking free GIGABYTES of disk is considered full? 10% of 1TB is what - 100GB? That's a lot of disk just sitting around to make the OS happy...

I remember when 20 MEGABYTES was a decent capacity of hard drives...
 
fmalloy said:
Thank you. I do understand that data is accessed differently in an SSD, and that they optimized recent OSes for SSD access. And Apple says they don't practice planned obsolescence... :mad:

I reviewed a couple of videos on how to replace/add an SSD to the 2011 iMac and - sorry - for me too many steps and things to take apart and put back together for a computer that won't even take the latest OS. Sure looks to me Apple said "how can we make it as difficult as possible to replace the hard drive, which, next to RAM, is the most common thing to replace?"

Well, they achieved their mission.
[doublepost=1539031554][/doublepost]
Two freaking free GIGABYTES of disk is considered full? 10% of 1TB is what - 100GB? That's a lot of disk just sitting around to make the OS happy...

I remember when 20 MEGABYTES was a decent capacity of hard drives...
Click to expand...

When I had a 2011 model I used a delock thunderbolt 1 enclosure with a SSD instead of surgery to access and replace the original HDD.

http://www.synchrotech.com/products...-external-enclosure-delock-42510.html#support

(If you had a usb 3 computer, that would be much cheaper vs thunderbolt, but 2011 models are USB 2 only.)

If you choose this option, make sure to get a thunderbolt 1/2 cable as well, there is not one included in the box with the enclosure.
 
Richdmoore said:
When I had a 2011 model I used a delock thunderbolt 1 enclosure with a SSD instead of surgery to access and replace the original HDD.
Click to expand...
Thank you - this certainly looks like a reasonable alternative!

Would any Thunderbolt SSD drive work and be bootable?
 
Wonder it boots at all. Hard drives require a suggested 15% free space to work anywhere near capacity.

When I had that model a Silicon power external TB drive worked very well. Clone over the operating system to the external and select it as the boot drive is System Preferences > Startup Disk.
 
nambuccaheadsau said:
Wonder it boots at all. Hard drives require a suggested 15% free space to work anywhere near capacity.

When I had that model a Silicon power external TB drive worked very well. Clone over the operating system to the external and select it as the boot drive is System Preferences > Startup Disk.
Click to expand...
Ok, thanks. First I'll clear up space, then erase and reinstall the OS. If that's not sufficient I'll look into the external Thunderbolt drive.

Thanks for your help.
 
fmalloy said:
Thank you. I do understand that data is accessed differently in an SSD, and that they optimized recent OSes for SSD access. And Apple says they don't practice planned obsolescence... :mad:

I reviewed a couple of videos on how to replace/add an SSD to the 2011 iMac and - sorry - for me too many steps and things to take apart and put back together for a computer that won't even take the latest OS. Sure looks to me Apple said "how can we make it as difficult as possible to replace the hard drive, which, next to RAM, is the most common thing to replace?"

Well, they achieved their mission.
[doublepost=1539031554][/doublepost]
Two freaking free GIGABYTES of disk is considered full? 10% of 1TB is what - 100GB? That's a lot of disk just sitting around to make the OS happy...

I remember when 20 MEGABYTES was a decent capacity of hard drives...
Click to expand...

I do too. Apps move much more data around these days. You need to have space for temp files plus some free space for swap should that become necessary. Your RAM is 12GB, right? What was it when HDDs were 20MB?

I don't think the move to SSD is as much planned obsolescence as it is laziness on the part of developers who don't feel they need to spend time optimizing IO because it isn't the bottleneck it once was.
 
You've got [essentially] 3 choices:
1. Pry open the iMac and put an SSD inside
2. Add an EXTERNAL thunderbolt SSD and use it as a boot drive (recommended)
3. Start shopping for something new or newer.

You DON'T NEED a 1tb thunderbolt drive.
250gb will do fine.

Put OS, apps, and [basic] accounts on the SSD.
Leave large libraries (movies, music, pics) on the internal drive (they don't "need speed").

This should give you a few more years of life out of it, with the least trouble...
 
In addition to a relative lack of free space, your old disk drive probably has a bunch of remapped sectors, marginal sectors that require internal retries, and so on. 10% is maybe too much for a 1 TB drive, but only having 2 GB free is definitely going to be hard on the filesystem space allocator and you likely have larger files fragmented all over the drive. I'd suggest something like 30-50 GB free as a minimum.

Note that SSD's also don't like to be very full, and there the rule of thumb is more like 75% free as a good maximum. Because of the way SSD's work, you want to leave a fair amount free so that garbage collection doesn't have to kick in frequently in the middle of I/O operations. It also leaves room for failing or overused pages to be mapped away.
 
Ok, so to update (as if anyone cares), I freed up a little more than 10% of disk space (didn't make much of a difference), then completely erased the drive, re-installed Sierra (it won't install Mojave), then restored from Time Machine backup. This seemed to make a big improvement in performance. I see much less pinwheels, task switching and user switching is faster, and I notice much less constant disk accesses while idle. It now seems fairly usable again.
 
fmalloy said:
Ok, so to update (as if anyone cares), I freed up a little more than 10% of disk space (didn't make much of a difference), then completely erased the drive, re-installed Sierra (it won't install Mojave), then restored from Time Machine backup. This seemed to make a big improvement in performance. I see much less pinwheels, task switching and user switching is faster, and I notice much less constant disk accesses while idle. It now seems fairly usable again.
Click to expand...
This may not last long. A good solution still is to get a 120-256 GB Thunderbolt SSD to use at the boot drive.
 
I have an internal 256GB crucial BX100 SSD in my iMac 2011 27”. It boots in 15 seconds to High Sierra. It is the only drive I have in it and I just use a 4TB USB WD drive to hold other files/Time Machine. I have 12GB Ram and upgrading it to 24GB. I bought TimeTec memory.
https://www.amazon.com/gp/aw/d/B00SNM1LHS
 
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