Slow to boot up Mac, Looking for Resolutions

D.I. Johnson wrote:

Your Mac also appears to have a Fusion drive installed. That is both a small capacity SSD and a larger HDD working together as a single unit. From time to time these "fused" drives become split and the performance really takes a hit. Without further diagnostic we can't yet say that your drive is split, but the potential is there.

Fusion Drive is intact. You can tell because both the internal SSD (disk0) and the internal HD (disk1) are part of the "disk2" item which is the actual Fusion Drive. I think the older versions of EtreCheck may have shown this a bit more clearly, but you can see "disk1s2" under the internal HD is listed as "Fusion Drive", then immediately under that it shows "disk2" as "Virtual APFS Virtual Drive" which is the actual "Fusion Drive" item.

    disk0 - APPLE SSD SM0032L 28.00 GB (Solid State - TRIM: Yes)
    Internal PCI-Express 8.0 GT/s x2 NVM Express
        disk0s1 - EFI [EFI] 315 MB
        disk0s2 [APFS Fusion Drive] 27.69 GB
            disk2 [APFS Virtual drive] 1.03 TB (Shared by 6 volumes)
                disk2s1 (APFS) [APFS Container] (13.20 GB used)
                    disk2s1s1 - Macintosh HD (APFS) [APFS Snapshot] (13.20 GB used)

 
   disk1 - APPLE HDD HTS541010A9E632 1.00 TB (Mechanical - 5400 RPM)
    Internal SATA 3 Gigabit Serial ATA
        disk1s1 - EFI (MS-DOS FAT32) [EFI] 210 MB
        disk1s2 [APFS Fusion Drive] 1000.00 GB
            disk2 [APFS Virtual drive] 1.03 TB (Shared by 6 volumes)
                disk2s1 (APFS) [APFS Container] (13.20 GB used)
                    disk2s1s1 - Macintosh HD (APFS) [APFS Snapshot] (13.20 GB used)

The HDD component of your Fusion drive also is a slower 5400 rpm rotation speed. These drives are notorious for being a bottleneck on that year iMac. A properly working Fusion drive will compensate for that bottleneck. But performance is terrible when it isn't.

Fusion Drive performance here is definitely slow, but it is hard to say how much is caused by Avast & MalwareBytes and how much by a worn out or failing Hard Drive.

Running DriveDx (free trial period) and posting the complete text report here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar can allow us to review the drives' health reports.

Yeah, that Hard Drive is just starting to fail with 22 reallocated sectors.

Currently there are no pending sectors awaiting reallocation (attribute # 197) which is good, but that doesn't mean that there may be some other sectors that may be having trouble being read that have not reached the point of complete failure of the sector.

I have never seen how fast the Hard Drive failures progress since either the drives are so bad, or they are just starting to fail like this one & I replace them so the user doesn't have to worry. You may want to perform a Disk Utility First Aid scan on the file system of the hidden APFS Container to see if any errors need to be repaired. Within Disk Utility you may need to click "View" and select "Show All Devices" before the hidden Container appears on the left pane of Disk Utility.....selecting the "Fusion Drive" item may also be a good idea. Even if First Aid says everything is "Ok", click "Show Details" and scroll through the report to see if any unfixed errors are listed. If there are errors, then run First Aid again until they are gone. If after several scans the errors remain, then try running First Aid while booted into Recovery Mode.

Then run another EtreCheck report after the First Aid scan runs clear now that you uninstalled the suspect software to see if the performance of the Fusion Drive has improved and by how much. And to ensure that all of the remnants of those uninstalled apps are completely gone....sometimes pieces of them may remain behind.

If the speed & performance improves, then you may want to monitor the health of the internal Hard Drive to see if any more Reallocated Sectors/Events occur and whether there is a change in the "Current Pending Sector Count". However, you should be planning on how to deal with the failing Hard Drive. Would you prefer to spend money to have the iMac repaired to replace the internal Hard Drive, or rather use an external USB3 or Thunderbolt2 SSD instead? An USB3 SSD would have a maximum speed of about 400-500MB/s due to the limited 5Gb/s USB3 port while a Thunderbolt2 SSD could potentially reach speeds up to 40Gb/s or about 5GB/s (5,000MB/s) depending on the SSD.

#1: Get rid of Avast. It serves no purpose other than to eat resources and slow down your Mac.

#2: Get rid of MalwareBytes. It

s find if you want to do a one time scan because you believe you installed something you shouldn't have, but you have it actively running, which will also bog things down.

#3: The Fusion Drive is bogging things down. Possibly because the extremely slow mechanical hard drive may be failing.

I would seriously consider looking into a new machine. You could improve performance quite a bit by moving to an external SSD as a boot drive, but any Apple silicone base Mac will run circles around even the fastest Intel based Macs.

You only posted the DriveDx report for the SSD. The SSD looks good. It is rare the SSD's health report will show anything useful these days, at least for the Apple OEM SSDs since they don't include too much information, but it never hurts to check. The other day I was assisting another user and their SSD health report showed major & very odd issues (very rare).

Please post one for the Hard Drive as well. You have to select the other physical drive shown on the left pane of DriveDx and click "Save Report" button.

There are definitely a few things going on.

Start by updating your Time Machine backup. Making sure your stuff remains accessible is the first priority.

Then disable and uninstall the Avast clean up and anti-virus software. The Mac is very capable of taking care of itself if you keep it updated. Avast and other similar software often get in the way and hits the Mac's performance. Likewise, if you have Malwarebytes' software set to be actively scanning the computer, you can safely disable that. It's fine to use the software to occasionally scan the Mac, but don't allow the software to run all the time.

• Protecting against malware in macOS - Apple Support

Your Mac also appears to have a Fusion drive installed. That is both a small capacity SSD and a larger HDD working together as a single unit. From time to time these "fused" drives become split and the performance really takes a hit. Without further diagnostic we can't yet say that your drive is split, but the potential is there. A split drive can be fixed as long as both devices are working properly, and that's not difficult. Apple provides guidance for that.

I'm a little fuzzy on the diagnostics of Fusion drives, but we have users here in the Community who can help figure this out.

The HDD component of your Fusion drive also is a slower 5400 rpm rotation speed. These drives are notorious for being a bottleneck on that year iMac. A properly working Fusion drive will compensate for that bottleneck. But performance is terrible when it isn't.

chowdahyeti wrote:

I have AppleCare, would this be something they replace for me with the hard drive?

Hard to say. As long as the Apple service diagnostics find a problem with the Hard Drive and you still have Apple Care, then Apple should cover the Hard Drive replacement under warranty. Run the Apple Diagnostic to see if any hardware issues are detected. If it detects a problem with the Hard Drive, then the service diagnostics should also see the drive as bad.

If the service diagnostics don't detect a problem, it will be a hard sell to get Apple to admit there is a problem with the Hard Drive at least at this time. You could try showing the tech the DriveDx output showing the SMART health attributes showing the start of the drive failure, but I'm doubtful the tech will know what they are seeing since Apple doesn't train their techs to look at that data....they only train them to rely on the results of their diagnostics.

Thanks for the Fusion drive guidance. I appreciate your useful info.

I'm curious... the OP's report shows write/read speeds as 220/247 MB/s. What transfer speeds would you expect to normally see from this Mac configuration when working well?

Will def be following this thread.

D.I. Johnson wrote:

Thanks for the Fusion drive guidance. I appreciate your useful info.

I'm curious... the OP's report shows write/read speeds as 220/247 MB/s. What transfer speeds would you expect to normally see from this Mac configuration when working well?

I thought you would appreciate the information.

The Apple internal SSD in the 2019 model is an NVMe based SSD which should be at least in the 2,500MB/s range (perhaps a bit more). With older iMac models (IIRC, perhaps about mid-2015) the Apple SSDs were SATA based so those SATA III based SSDs would have a maximum speed of about 500MB/s.

However, with the Fusion Drive setup, the speeds will be less, perhaps much less depending on the size of the internal SSD. I recall some discussion about this in another thread (perhaps in the Lounge) since none of us could say with certain what the Fusion Drive speeds should be on any specific model as we wanted to know when the speed seemed off.

I would say the read speeds for a Fusion Drive in a 2019 iMac should be at least 1,500MB/s if not a bit more. Write speeds will definitely be slower.....I usually consider write speeds to be about half of the read speeds only because of other processes interfering. At least this seems to be the case in the speeds I've seen displayed on the EtreCheck reports posted on the forums.

For a Fusion Drive in this 2019 iMac, I would expect the write speed in the EtreCheck report to show at least 500-700MB/s.