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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > iMac lag time - suddenly slow?

iMac lag time - suddenly slow?
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MrsLarry
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Oct 26, 2010, 12:24 AM
 
Specs:
24" iMac, circa June 2008, running 10.5.8
2.9 Ghz Intel Core 2 Duo
2 GB 800 Mhz DDR2 SDRAM
300GB capacity, 94GB used

Recent changes:
~2 months ago, started hearing loudish fan noise, was concerned for my HD going, bought a refurb WD My Passport USB 2.0 external drive to back up. Started running time machine, and coincidentally enough, fan noise also stopped.

~A week ago, upgraded Adobe products to CS5, at the time everything seemed to be working.

~2 days ago, Time Machine starts getting errors on backup

The problem:
Today, lag on everything. Open Entourage mail, start writing an email. frozen. hard reset. Open firefox, bouncing icon, waiting, waiting, bouncing, waiting... maybe 3 mins? come on macnn to post issue started typing, Opened system prefs. frozen. Hard Reset. It just keeps freezing!!

I'm clearly out of warranty, but have no problem bringing it to the Apple Store if it needs something. Is there any tests I can run? any ideas you have would be saving my life!!!
     
Big Mac
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Oct 26, 2010, 12:30 AM
 
Yup, hard drive problem. You should have replaced the drive when you first started having problems. Make sure everything is backed up that is needed and replace the drive.

"The natural progress of things is for liberty to yield and government to gain ground." TJ
     
reader50
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Oct 26, 2010, 01:02 AM
 
I agree, likely drive problem. Turn off Time Machine until you get this fixed - a TM run stresses both drives.

Check the system log in Console utility for messages. Or Disk Utility for SMART status on the internal drive. The problem could be either drive, and it would be best to replace the right one.
     
MrsLarry  (op)
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Oct 26, 2010, 09:33 AM
 
Ugh. This is unhappy news. I've seen a few videos of people replacing them on their own, and my husband, who's not a Mac guy, but is an IT guy is convinced he could do it.

Would you attempt it? Or bring it to the Apple Store?

What hard drive do you recommend?
     
Waragainstsleep
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Oct 26, 2010, 10:50 AM
 
The trickiest part is getting all the dust off the panel and the glass when you put them back together. Apple techs wear gloves like cinema projectionists when dealing with Alu iMacs. They are easy once you've done a few. Its not like swapping the drive in run of the mill PC tower, but its not brain surgery.
I have plenty of more important things to do, if only I could bring myself to do them....
     
P
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Oct 26, 2010, 11:33 AM
 
Originally Posted by MrsLarry View Post
What hard drive do you recommend?
1TB WD Caviar Black - which also happens to be what Apple puts in their iMacs these days. Fast for a regular HDD, yet not insanely priced and reasonably quiet.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
seanc
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Oct 26, 2010, 06:26 PM
 
I turned down changing the HDD in one of these, due to the glass screen.

Smart utility is good for checking the SMART values.
SMART reporter will also do this, you have to right click the drive while in the preferences window and view SMART attributes.
     
MrsLarry  (op)
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Oct 26, 2010, 06:43 PM
 
well... I don't know if this makes any sense to you all, but it sure doesn't look good:

     
seanc
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Oct 26, 2010, 06:46 PM
 
Yep, new drive required. On a good drive, all of those red values would be showing 0.

I'd be interested to know whether Disk Utility is showing the drive as verified or not?
     
MrsLarry  (op)
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Oct 26, 2010, 06:51 PM
 
Negatory.



Crap.
     
reader50
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Oct 26, 2010, 07:17 PM
 
MrsLarry, click on the Hitachi line above Macintosh HD. You don't need to start a scan, Disk Utility will show it's version of SMART status at the bottom of the window.

Internal HD definitely needs replacing, and soon. I don't like the Raw Read Error Rate either (SMART attribute #1).

I'd recommend you stop using the iMac until the drive is replaced. Conserve whatever life is left in the internal HD in case you have to retrieve some data from it. Something that didn't make it to the backup drive. You should ask to keep the old drive after the swap, just in case any data turns up missing.
     
MrsLarry  (op)
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Oct 26, 2010, 07:42 PM
 
Huh interesting, it says verified:

     
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Oct 27, 2010, 03:21 AM
 
Yes, that's the flaw in SMART. We've been over it several times around here, but the short version is this: The manufacturer sets a conversion algorithm from the raw value to the "status" value and then alerts if the status value goes past a threshold. If you look closely in that first screen shot, you see that the status value (column "value") is over the threshold in all cases, so according to the manufacturer, you have no problem, and those lost files are probably your imagination...
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
OreoCookie
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Oct 27, 2010, 05:11 AM
 
Don't trust it: the SMART status often does not change even though the harddrive is failing, i. e. expect false negatives. I concur that it seems as if your harddrive is failing. You should get it replaced with a larger harddrive after making a last backup. The sweet spot in terms of price per gigabyte lies with 1.5 TB drives and I recommend you get one of those.
I don't suffer from insanity, I enjoy every minute of it.
     
seanc
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Oct 27, 2010, 05:24 AM
 
I totally agree with P and Oreo, which is why I always request that people run a utility such as SMART utility.

I have drives with ~700, ~5000 bad sectors that are not tripping SMART.
The one with ~5000 uncorrectable sectors is still in use, the owner refuses to replace it until it dies. It's very very slow.

I have another with ~26,000 bad sectors! That one managed to fix itself enough for me to mount some Exchange data stores that were on it. At 26,000 uncorrectable sectors, it does trip SMART.
     
Waragainstsleep
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Oct 27, 2010, 06:42 AM
 
Disk utility is particularly bad at giving useful info about SMART, but the number of times I've seen drives grinding, clunking and failing horribly and obviously without any SMART error whatsoever is very high indeed.

I would argue that 2TB is the sweet spot nowadays actually. Especially with barebones 3TB drives arriving imminently.
I have plenty of more important things to do, if only I could bring myself to do them....
     
OreoCookie
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Oct 27, 2010, 07:35 AM
 
@Waragainstsleep
Disk Utility isn't any worse, it just doesn't give any details beyond the SMART status (such as number of faulty blocks, spin-ups, etc.).
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Waragainstsleep
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Oct 27, 2010, 08:50 AM
 
I mean its not something you can rely on. At all. If it reports a fault, I double check with something else. If it doesn't, I still use other tools to check. Hence its useless. It literally provides no meaningful use.

I have seen it comdemn drives which promptly come back from the dead with minimal treatment. I think SMART reporting was a bit of an afterthought for Apple tbh. They could have included a rudimentary SMART check years before they did (Was it Leopard it came in?) They don't provide any SMART tools for their techs that I know of, though their own branded diagnostics may be using them I guess.
I have plenty of more important things to do, if only I could bring myself to do them....
     
OreoCookie
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Oct 27, 2010, 09:00 AM
 
I think there is a misunderstanding: SMART is not a technology developed by Apple, it's an industry standard. The hard drive diagnostics record many parameters (hours of use, spin up cycles, number of faulty blocks, temperature, etc.) and then, if certain thresholds are tripped (which depend on the particular make and model), the SMART status is tripped and changes from Verified to something else.

Apple's Disk Utility reads out just the SMART status without reading out the other parameters (at least they are not displayed) so it relies on the manufacturer to set reasonable values to where the SMART status should change. The SMART status is definitely not something to rely on, but that's not Apple's fault. Not all failures are detected by the parameters that are measured. And perhaps some of the thresholds are chosen incorrectly. In practice this means you can have false negatives (failure not detected), but I have yet to see a false positive (drive is reported as failing, although it's fine). So if your drive' SMART status has changed from Verified to failing or failed, your harddrive really is toast.

You can read out all the SMART data via various tools on OS X, I use smartmonctl (free command line tool), but there are GUIs for that.

If there is smoke coming from the hood of the car, you don't keep on going even though the engine failure light isn't on.
I don't suffer from insanity, I enjoy every minute of it.
     
MrsLarry  (op)
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Oct 27, 2010, 01:22 PM
 
So, other than the obvious "bigger is better" why such a large HD? I was considering 500GB, until I see posts suggesting 1-2 TB. I can't imagine ever needing that much space.

Is it like a "more lanes on the highway = less traffic = faster drive" sort of thing?

(Ugh, I sound like such a 'damsel is distress' - gross!)
     
OreoCookie
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Oct 27, 2010, 02:46 PM
 
It's just about getting the best bang for the buck and 500 GB are not it -- especially if you add the money it costs to install the new harddrive.
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Big Mac
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Oct 27, 2010, 04:33 PM
 
Originally Posted by MrsLarry View Post
So, other than the obvious "bigger is better" why such a large HD? I was considering 500GB, until I see posts suggesting 1-2 TB. I can't imagine ever needing that much space.

Is it like a "more lanes on the highway = less traffic = faster drive" sort of thing?

(Ugh, I sound like such a 'damsel is distress' - gross!)
And in addition to what OC, said, what you say is true to an extent. Hard drive speeds slow down after being filled to a certain capacity. If you keep your drive less than half full, it will perform faster.

"The natural progress of things is for liberty to yield and government to gain ground." TJ
     
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Oct 28, 2010, 04:49 AM
 
My recommendation was based on the fact that that particular drive is a very nice one. I suspect that any 500 gig drive you can find today would be slower, because any 500 gig drive you find will be either old or a budget model. Looking at newegg right now, the drive I recommended (WD Caviar Black 1 TB) is $87. There is a 640 gig version of the same drive for $64, that's a decent deal but more $/GB. Most of the other drives that are cheaper are either significantly smaller (<500 gigs) or slower, or both. There are a few that look interesting - I've had good luck with Seagate's Barracuda drives, and they have a 1.5TB model for $8 less - but that's about it. HD speed is likely to be the bottleneck in everything you do, so it's worth getting a good drive - or something complicated like an SSD setup, but that might be outside the scope of this discussion.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
Waragainstsleep
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Oct 28, 2010, 05:43 AM
 
Originally Posted by OreoCookie View Post
I think there is a misunderstanding: SMART is not a technology developed by Apple, it's an industry standard. The hard drive diagnostics record many parameters (hours of use, spin up cycles, number of faulty blocks, temperature, etc.) and then, if certain thresholds are tripped (which depend on the particular make and model), the SMART status is tripped and changes from Verified to something else.

Apple's Disk Utility reads out just the SMART status without reading out the other parameters (at least they are not displayed) so it relies on the manufacturer to set reasonable values to where the SMART status should change. The SMART status is definitely not something to rely on, but that's not Apple's fault. Not all failures are detected by the parameters that are measured. And perhaps some of the thresholds are chosen incorrectly. In practice this means you can have false negatives (failure not detected), but I have yet to see a false positive (drive is reported as failing, although it's fine). So if your drive' SMART status has changed from Verified to failing or failed, your harddrive really is toast.

You can read out all the SMART data via various tools on OS X, I use smartmonctl (free command line tool), but there are GUIs for that.

If there is smoke coming from the hood of the car, you don't keep on going even though the engine failure light isn't on.
I'm assuming this is aimed at me. I know what SMART is, but I question Apple's implementation of it in DU. Firstly it took them years to bother at all which rings alarm bells for me. Second, I simply don't trust DU to read and interpret the info correctly since it is quite common for it to moan about perfectly functional disks and change its mind several times a day about one disk that may or may not be working correctly. Or at all.

If you have ever tried to explain anything to Apple about how your Mac is running too hot or the fan is too fast, you will find they hold no stock whatsoever in your information because they didn't develop the software thats reporting the temps or fan speeds. Xserves being the main exception. Menu meters and Temperature Monitor hold no sway with them at all.
Apple does not bother to mention SMART to its technicians that I recall. It wasn't in the training and if its in any service manuals then thats a more recent development than adding it to DU. In short they don't seem to trust their own software when it comes to SMART, but I had come to that conclusion independently anyway. When DU reports no SMART issues with a disk that is almost too hot to touch, I question it.
I have plenty of more important things to do, if only I could bring myself to do them....
     
MrsLarry  (op)
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Dec 1, 2010, 09:19 PM
 
And that's the end of that story. I backed up with Time Machine, bought a new 1TB drive per the reco's here, I continued to use the iMac (lightly) until I knew my husband and I had time to do the swap. A few days ago, powered it up and ... nothing. Gray screen with the circle with a slash through it symbol. (I thought a skull and crossbones would have been more appropriate)

Anyway, after a needle-in-the-haystack search for a Torx #8 screwdriver (Sears, by the way) we installed the new hard drive. Per instructions on apple's site, I started from the install disk, formatted the drive, then "restored from Time Machine backup" and 2 hours later I was back in business! It was surprisingly easy!

Here's a photo from the surgery:
     
Waragainstsleep
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Dec 2, 2010, 06:01 AM
 
I think there is still a misunderstanding about what I'm saying. I know SMART is not an Apple technology, I'm not criticising their implementation of it either. I'm simply saying that it is effectively useless when trying to decide whether or not a disk needs to be replaced. Any other SMART utility is probably just as useless but I never bothered to look into them because the last time it occurred to me to do so there weren't really many about.
Any SMART software is just reading numbers from the disk itself and while its entirely possible to encounter an error doing just that, its not all that likely.

Probably the majority of disks with mechanical faults report no issues whatsoever via SMART, which makes it considerably less useful than it sounds on paper. It works the other way too. I have seen SMART failures come back to life and suffer no further fault for years and SMART failures on disks that weren't having issues in the first place.
With my own drives, if I get any failure from Disk Utility or Disk Warrior etc that can't be fixed by those programs, I run a backup and either see how it holds up or do an erase and install. If it fails in short order after that, I replace the disk.
With customers, I give them the choice. They can trust a potentially failing disk or buy a new one. I just can't afford to throw out a drive based on a potentially erroneous line of red text. Some people can.
I have plenty of more important things to do, if only I could bring myself to do them....
     
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Dec 2, 2010, 08:45 AM
 
There is a study on the effectiveness of SMART available here. Short version: If the number of scan errors or the number of reallocated sectors (3 figures) goes up, your drive is failing. Less than half (44%) of all drives that fail can be detected this way. Much of the remaining 56% can be attributed to age (>2 years, but then Google servers run their drives harder than desktops) or model-specific failures. In essence, parts of SMART IS interesting, but it tells far from the entire story.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
   
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