Resolved SSD slows way down on big file transfers

[mdgm]

Just not sure if it would be worth it to go the nvme route for better performance with an external drive on the TB2 port

The 2011 iMac has a TB1 port. You would see a small gain over SATA III 2.5" internal, but the difference isn't huge. An advantage though is if you used the external drive with a newer Mac down the line after retiring the 2011 iMac you'd see a lot faster speeds than SATA III.

There are cheaper TB options such as finding a TB1/2 external but the speed isn't as good.

 

[Allistah]

Yeah the more I think about it, this is an old machine and an internal sata3 drive will be fine as long as it doesn't get driven into the ground like this OCW drive did. I just reinstalled BS 11.1 and everything is now updating so once things calm down, I'll do one last check to see if that perf thing still exists. Some people claimed that they had wonky SSD perf issues and a complete wipe of everything on the drive and starting over helped out a lot. Not to say I still don't need a new drive, I'm just curious really. Will be looking up 32gb of ram too - it doesn't seem to be too expensive.

Once this machine sits overnight to update all the things and has time to settle down, I'll check it first thing in the morning and see what happens.

 

[mdgm]

Things to look out for with memory would also include an application with a bad memory leak. This could be solved by downgrading/upgrading to a different version of the application without the problem.

For light use something must have seriously gone wrong, or running defragmentation tools (not a good idea for SSDs as mentioned earlier) to do so many writes.

For most light users 50GB a day on average for 5 years would probably be a lot more than what they would normally do.

Then there's things say if you have an app with a huge library of data if it's written poorly and rewrites the entire library if you make a small change that would explain a lot of writes.

If you work with large video files and edit those repeatedly then depending how the software works that could involve a lot of writes.

SSDs provide less of an advantage for large sequential writes than they do for writes that are more "random".

The best way to see where the problem is, is to monitor your writes using the computer normally and identify the problem when it occurs.

 

[HDFan]

What happens is that it is nice and fast when it starts and then it chokes down to almost a crawl. Then it speeds up again, then slows way down to almost nothing.

Sounds like the behavior of an SSD with an internal write cache when data is being transferred to the SSD faster than it can write it. When it fills up the controller has to stop accepting data until it can finish flushing the cache to storage.

 

[mdgm]

That's a good point.

Have you always seen this issue or just recently?

If just recently then maybe the amount of writes made to the SSD could be a factor. Like HDDs, SSDs may last a lot longer/shorter than they are rated for.

It wouldn't be surprising if wiping the SSD helped as with a huge amount of writes problems that should normally take years to develop to a point where they are a problem could have developed in just a matter of months.

 

[Allistah]

I tried the data thing again and it bogged down like it did before. What is interesting is that this drive has 218 TBW which is crazy in 4 months of time. My 2015 MBP which I have a 2TB NVMe drive in only has 82 TBW and that drive is a year and half old. That machine also has 16 GB of memory and I work with all sorts of huge video files on it.

Something went screwy with this OCW drive. For a daily use machine that is web/email and the occasional game, there's no way I burned through 218 TBW in 4 months. Now I know that indicator doesn't lie - it is what it is - but my usage is not indicative of 218 TB of writes in that amount of time.

So I wonder if the drive I got actually had writes on it when I got it and I never noticed the slowdown. I just installed it and never checked to see what it could do in regard to sustained writes when it was new. I'm going to replace it with a 1 TB Samsung 860 EVO. You can bet I'll check all those stats when I get it and keep a much closer eye on it. I was going to go with 32GB of ram, but I think I'm going to hold off on that one and just watch the drive for a while after I install it once it gets delivered on Saturday.

 

[Allistah]

I just wanted to make sure I had this SSD plugged into the right port. Maybe it matters and I don't know it. Currently it is plugged into the port labeled SATA 0 (red arrow pointing at in the image) where the original mechanical hard drive was plugged into. Thats fine right? I don't have to plug it into the SATA 1 port? Image below is from OCW. The DVD drive is currently plugged into SATA 2 and SATA 1 is empty.

The Samsung 860 EVO 1TB has been ordered. This mystery around this drive being spent is driving me nuts, I think I just need to emotionally let it go and keep an eye on the new one. I hate not knowing why something happened - it drives me crazy. ;-)

 

[mdgm]

There are three SATA ports. It's normal to have a spare port if you didn't get it from the factory with a ssd. The spare port can be used to add a second SSD at full speed and place it under the optical drive. The optical drive SATA port is limited to SATA II (3Gbps) so you should only put a SSD where the optical drive is if you want to have 3 internal SSDs.

If you look at the iFixit guide or OWC video they use strong adhesive tape to secure the SSD beneath the optical drive to the iMac case and you have to add a SATA cable to use the port. To get at where to install it you have to remove the optical drive.

By far the easiest thing to do is to leave the spare port unused and optical drive installed and just use the port that the factory hdd used. SSDs are cheap enough these days that one should be sufficient for internal storage.

I've never opened my iMac but it would make logical sense for port 0 to be the one used by the factory hard drive.

 

[Allistah]

I got my new Samsung 860 EVO 1 TB drive a few hours ago. I used Carbon Copy Cloner to clone the drive from the OCW drive to it and then installed it.

I ensured that the total bytes written was about the size of the data transferred - making sure it wasn't prematurely spent. It's a brand new drive which is what I would expect. I left the new SATA3 cable in there and just used it so I know it's got proper shielding.

I could tell right away that this drive is a lot faster. Instead of taking 6m 4s to erase it like the OCW drive, this Samsung drive took 24 seconds to do the same thing - and that was even on an old USB cable adapter.

Boot time was a lot faster as well once I booted it up. got 568 MB/sec read and 449 MB/sec write. I'm happy with that for this machine.

I also did the same test transferring a file from my NAS - the original action that alerted me to the problem the very first time. I only let the 55 GB file go for 15 GB since I could clearly see that the problem was gone. You can see a nice solid transfer rate below. It was indeed, the drive.

Once again, I want to thank everyone that replied in this thread. Thats what I love about these forums. Special thanks to @mdgm for closely examining the data I posted about my drive and seeing that it was spent.

Thanks again,

-Allistah