Strange behaviour from OWC SSD Drive - iMac mid 2011

[adamlbiscuit]

Hi all

I am writing with regards to my Mid-2011 27” iMac that I am attempting to resurrect and repurpose as a nice YouTube / Netflix / iTunes machine for the bedroom.

It previously suffered a Hard Drive failure (the one that originally came with it) so I purchased an SSD upgrade kit from Amazon, this one to be precise:

OWC SSD Upgrade Bundle For 2011 iMacs, OWC Mercury Electra 250GB 6G SSD, AdaptaDrive 2.5" to 3.5" Drive Converter Bracket, In-line Digital Thermal Sensor Cable, Installation tools

Experience the extreme performance of an OWC SSD upgrade with this easy DIY SSD and hard drive replacement kit. Add an SSD to your hard drive equipped iMac to experience faster booting, near instant application launches and lightning fast data transfer speeds.OWC's in-line solution is the only ha...

www.amazon.co.uk

It features a 250 GB OWC Mercury Electra 6G. I’m not very knowledgeable about SSD brands but I’d heard good things about OWC so I went ahead (and for £99 with all the tools included, it seemed like a safe bet).

I installed the SSD a couple of days ago following all of the instructions, and bar a screw that wanted to be difficult, it went rather well.

Unfortunately, I’m seeing some things about this SSD that I am concerned with, which I will list below:

• The drive is very fast. Boot times are great and the apps open promptly - honestly, at first glance it’s just as fast at booting things as my AS Mac mini. However, the Black Magic Speedtest is where things take a bit of a turn. I’m seeing read / write speeds of about 400 / 500 mb/s which is fine. However, this soon drops to as low as 17 mb/s (see video). I figured I’d ignore that Speedtest and instead focus on real world performance which seems ok, after all, it’s going to be used for very basic tasks. Still, it’s leaving a bit of a sour taste and thus…

• Curiosity got the better of me and I downloaded Drive DX. Although it says it passes its S.M.A.R.T tests and is in good health, there are some errors that concern me (see screenshot).

Now, here’s what I’ve tried:

• OWC recommend that TRIM not be enabled on their drives because they deal with garbage collection in their own way. However, I’ve read a lot of threads here and elsewhere saying that while OWC drives don’t require TRIM, they’re still a lot slower without it. I used the Trimforce terminal command to enable TRIM in the hopes that it will resolve the above, however, no dice so far.

• I dismantled the iMac all over again to reseat the SATA cable. Unfortunately this did nothing, either.

So I’m willing to put it down to experience and purchase another SSD (not from OWC this time as, since purchasing, I’ve seen a lot of negative things said about their drives - so typical of me that I did not see this until now) but before I do this, I was wondering if there’s anything else I should try before spending another £100 on what is essentially a spare Mac that’s been unceremoniously brought out of retirement.

P.S: It’s worth mentioning that this drive is formatted as APFS. I don’t know if that brings up any inconsistencies with OWC drives / TRIM etc.

Thanks for reading!

 

[mj_]

A sudden and drastic drop in write performance is indicative of an SSD running out of cache and writing to poorly performing NAND chips instead. QLC-based SSDs typically show that kind of behavior due to the nature of QLC chips. I dare say a Samsung or Crucial SSD would have been a better choice. With that said you should keep in mind that you most likely won't notice a difference between your current SSD and a different one as the OWC seems to perform adequately enough for everyday use. Write performance is only important if you tend to write a lot to your SSD, e.g. doing extensive video editing. If you use it as everyday office machine it is almost completely irrelevant.

 

[adamlbiscuit]

A sudden and drastic drop in write performance is indicative of an SSD running out of cache and writing to poorly performing NAND chips instead. QLC-based SSDs typically show that kind of behavior due to the nature of QLC chips. I dare say a Samsung or Crucial SSD would have been a better choice. With that said you should keep in mind that you most likely won't notice a difference between your current SSD and a different one as the OWC seems to perform adequately enough for everyday use. Write performance is only important if you tend to write a lot to your SSD, e.g. doing extensive video editing. If you use it as everyday office machine it is almost completely irrelevant.

Thanks for your reply.

That makes sense - I hadn't considered the cache element (my knowledge of SSDs is quite limited evidently) and it does make sense given the drive speeds are fine initially prior to dropping.

You're right it does perform really well for my use case - I hate to say it but if not for me poking around and installing speed tests and diagnostics tools I probably wouldn't have had any worries. Perhaps a sign of me poking my nose around in things I don't fully understand haha

 

[mdgm]

You bought OWC's lower end SATA III (6Gbps) SSD. If performance is king they have a faster model the Extreme Pro 6G or you could look to use other brands as mj_ mentioned.

 

[adamlbiscuit]

You bought OWC's lower end SATA III (6Gbps) SSD. If performance is king they have a faster model the Extreme Pro 6G or you could look to use other brands as mj_ mentioned.

Thanks for clarifying. To be honest as long as it's operating normally I'll be keeping this drive. I've got the M1 Mac mini for anything more intense, this is just going to be a Netflix machine for now.