Swap Memory in Catalina

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Swap Memory in Catalina

I am have problems with slow applications on my iMac. Mail in particular will no longer allow new e-mails to be created.

When I check the memory, I have plenty of spare physical memory, but Swap memory is large.

Rebooting resets the swap memory to zero and the slow response disappears, only to reappear a few hours later.

Etrecheck says that I have no problems.

Is it likely that I have a memory problem? Is there something I can do to avoid using swap memory when I have plenty of physical memory.

Posted on Jan 30, 2021 11:10 PM

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Answer 1

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Ruadh2 Author

Level 1

16 points

Mar 3, 2021 2:15 PM in response to Ruadh2

So, I've been monitoring this problem for a month.

Surprisingly, it has disappeared. I do not use any swap memory, even if I leave the computer on for days.

What has changed is that I've reduced the numbers of e-mails that I have open in MacMail. I've gone from 20 to 40 open e-mails to keeping it below 10. I suspect that it was MacMail that was somehow triggering the swap memory, and it slowness in MacMail and other applications.

Anyway, the problem has gone away, but is not solved per se. There does seem to be some application memory issues which trigger swap memory when it's not required and which impacts the computer's performance. But reasonably easy to avoid, even if I can't see how to fix the problem.

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Answer 2

Old Toad

Level 10

215,954 points

Mar 3, 2021 3:52 PM in response to Ruadh2

What has changed is that I've reduced the numbers of e-mails that I have open in MacMail. I've gone from 20 to 40 open e-mails to keeping it below 10. I suspect that it was MacMail that was somehow triggering the swap memory, and it slowness in MacMail and other applications.

That sounds like that was a major contributor to the problem. With 72 GB of RAM there's mp way you should have any swap files.

Having a lot of Safari windows open will also put a strain on the system.

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Answer 3

Ruadh2 Author

Level 1

16 points

Mar 3, 2021 8:37 PM in response to Old Toad

Old Toad wrote:

With 72 GB of RAM there's mp way you should have any swap files.

Having a lot of Safari windows open will also put a strain on the system.

Yes, I have a lot of Safari Windows too. So, it's interesting that Application Memory shortages can trigger Swap Memory even where there's lots of spare memory (memory pressure is green - see Monitor screen shot above). That makes my memory upgrade less useful.

There doesn't seem to be an easy fix to turn that Swap trigger off. https://apple.stackexchange.com/questions/340333/tell-macos-to-only-use-swap-and-compressed-memory-when-really-needed-macos-10-1.

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Answer 4

padams35

Level 4

3,613 points

Feb 2, 2021 10:10 AM in response to Ruadh2

Please post the Etrecheck results. (It is a long report, so use the 'additional text' forum posting option).

Swap: occurs when (a) memory is very stale and MacOS dumps it to swap as unused. (b) you ran something very very demanding that pushed other stuff into swap that hasn't yet been needed to come back out. Generally it isn't a problem as long as the swap used is much smaller than your free memory.

How long has it been since you last restarted?

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Answer 5

Feb 2, 2021 9:45 AM in response to Ruadh2

Hello

Welcome to Apple Support Communities!

If we understand your post correctly, when you check the memory on your Mac you have plenty but the swap memory is large so you want to know if there is something you can do to avoid using swap memory when you have plenty of physical memory. We're happy to h help!

It is normal to have a small amount of swap memory once you're getting low on RAM. It is also normal for that swap memory to add up over time depending on what you are running and then only reset to 0 after a restart.

Below is an article that will also help out with memory.

Check if your Mac needs more RAM in Activity Monitor

Let us know if you have any questions.

Thank you for using Apple Support Communities.

Take care!

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Answer 6

Ruadh2 Author

Level 1

16 points

Feb 5, 2021 5:08 PM in response to padams35

Etrecheck report - Catalina: Slow Mac Mail App

I've added the Etrecheck report.

I have a large amount of installed Memory - 72GB. In normal use I don't come close to that - maybe 25%.

I restart daily, and the problems cease with restart. But after use for a while (say, 12 hours) I get large Swap memory and very poor application performance on Mac Mail for instance. I don't think a brand new computer (seven months old) should need restarting more than once per day. Interestingly, for the past couple of days it's not using Swap memory at all. And it wasn't a problem when I first purchased it, starting a couple of months ago. So, an intermittent problem, perhaps.

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Answer 7

Halliday

Level 4

2,677 points

Mar 3, 2021 9:39 PM in response to Ruadh2

I would have expected better of Catalina (especially the version I used just before upgrading to Big Sur).

In fact, I wouldn’t even expect any “Compressed” memory—let alone “Swap”—so long as there is unused RAM!

Are you using the latest Catalina version?

Have you ever seen the sum of “Memory Used” and “Cached Files” get close to your 72 GB “Physical Memory”?

Unused memory (RAM) is a waste.

(On Big Sur, I see it actively reducing “swap”, when my memory needs reduce.)

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Answer 8

Ruadh2 Author

Level 1

16 points

Mar 3, 2021 11:15 PM in response to Halliday

Are you using the latest Catalina version?

10.15.7

Have you ever seen the sum of “Memory Used” and “Cached Files” get close to your 72 GB “Physical Memory”?

Never. I'm waiting for a big modelling project to try to test the limits. However, it's surprising that swap memory is generated at 25% utilisation if my MacMail has too many e-mails open, or Safari has too many open tabs.

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Swap Memory in Catalina

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