external drive speed on iMac

[roadkill401]

I have a 2014 iMac with an internal SSD drive. I get that it's fast by design.

I have had so many issues getting Sierra to work that I decided that rather than have an iMac that just doesn't work while Apple tries to figure it out, I reloaded El Cap back internally and purchased a 1tb SSD that is hooked up via Thunderbot2 (Thunderbay4mini).

I trie to load Sierra onto that is it seems to churn slow. Blackmagic shows it getting a read of 280mb/s write of 230mb/s. That seems awfully slow considering the drive is spec'd in the 500's

 

[hfg]

I assume you formatted the new SSD for OS X before using it (probably comes formatted as FAT for Windows compatibility).

Do you have "TRIM" enabled for the external thunderbolt SSD?

 

[joema2]

There are many different types of SSD drives, and many different benchmarks. The Transcend StoreJet 500 only delivered about 292 MB/sec write and 381 MB/sec read (on Blackmagic), despite being Thunderbolt interface.

I have four 2TB Evo 850s in a Thunderbay4 Mini, and in RAID-0 it delivers (on Blackmagic) 1171 MB/sec write, 1243 MB/sec read. I never tested them individually.

The Crucial MX300 is less expensive but some tests show it's not as fast. Blackmagic is just one test that apparently emphasizes serial I/O. In these tests the MX300 was generally pretty good but in the StorageMark IO/sec tests it was much slower: http://www.storagereview.com/crucial_mx300_ssd_review

The WD Blue 1TB SSD looks pretty good on these tests:

https://www.cnet.com/products/wd-blue-ssd/review/

But not these tests: http://www.storagereview.com/wd_blue_ssd_review_1tb

They all claim over 500 MB/sec sequential performance but there are major differences when benchmarked under different workloads.

 

[roadkill401]

Yes. I have turned on TRIM.

When I tried to load Sierra onto that drive, it was totally unusable. There was a dramatic lag in everything. for instance, it would take FaceTime 10+ seconds to load, initialize the camera and start to display a video feed of yourself. Safari took 3-4 seconds to load. The OS was beachball with just about everything.

I would have throught that an SSD drive connected via Thunderbolt would be somewhat responsive and actually works as an OS drive. I will re-format the drive and see how the performance is under Windows 10 bootcamp.

 

[bernuli]

What make/model SSD are you using? As joema2 stated, different brand/model SSDs offer different performance.

 

[Fishrrman]

OP:
Which SSD did you buy?
Did it come as a "standalone package" (i.e., in its own enclosure, "ready to go"), or did you buy a "bare" SSD and an enclosure to hold it?
IF you bought a separate enclosure, did you check before buying to see if it was SPECIFICALLY STATED TO SUPPORT UASP?
If the cable can be changed out, have you tried a different cable?

Just about any SSD in a USB3 enclosure with UASP should yield read speeds around 430mbps.
Write speeds will vary with the drive manufacturer and capacity.

 

[joema2]

OP:
Which SSD did you buy?
Did it come as a "standalone package" (i.e., in its own enclosure, "ready to go"), or did you buy a "bare" SSD and an enclosure to hold it?
IF you bought a separate enclosure, did you check before buying to see if it was SPECIFICALLY STATED TO SUPPORT UASP?
If the cable can be changed out, have you tried a different cable?

Just about any SSD in a USB3 enclosure with UASP should yield read speeds around 430mbps.
Write speeds will vary with the drive manufacturer and capacity.

Checking things like UASP is a good idea -- if dealing with USB. However I don't think it applies in his case.

He is using a bare 2.5" 1TB SATA SSD drive (brand not yet stated) in an OWC Thunderbay 4 Mini enclosure: https://eshop.macsales.com/item/OWC/TB4MJB0GB/

The interface to his iMac is Thunderbolt 2. There is no USB in the picture.

He probably should look up all available published benchmarks for his 1TB SSD drive, esp. extensive ones on sites like www.storagereview.com. That will give an idea what the real-world (not just spec) performance is on many different benchmarks.

I also don't know how the OWC Thunderbay 4 Mini behaves if he has mixed drive types inserted or if he's mixing Thunderbolt 1 and 2 devices on a single bus. On my OWC Thunderbay 4 Mini with 4 x 2TB Samsung EVO 850 drives in RAID-0, it slows down considerably if I mix Thunderbolt 1 and 2 on that same bus, but that probably would not affect a single drive. I have never tested only a single SSD drive in the Thunderbay 4 Mini, so I can't say what the performance would be.

 

[hfg]

Just for comparison, I tested my Micron (Crucial) M500 1TB SSD which is in a ThunderBay 4 connected to a 2015 5K iMac with internal 1TB SSD only. The BlackMagicDesigns speeds are shown below. If the OP happens to have a similar brand SSD, I could move mine to a ThunderBay 4 Mini to verify that I get similar results. My Thunderbay 4 also has a couple of 3.5" hard disks enclosed with the SSD.

I have had no problems with Sierra on the internal SSD of either my 2015 or 2014 5K iMacs (maxxed out with 1TB SSD). I have also booted OS X and Windows 10 from SSDs in the ThunderBay enclosure on both machines without problems.

 

[roadkill401]

Sorry for not getting back sooner. I have had my iMac in pieces so to speak. The SSD drive is a Mushkin Reactor 1tb MKNSSDRE1TB. With my drive, I am getting about 1/2 the speed shown in the Blackmagic shot.

I got the drive as I have been trying to diagnose why my FaceTime camera keeps on crashing every 3-4 hours. I wanted a separate drive to load El-Cap and Sierra to see if I could figure out what was causing the issue or if it was a hardware failure.

It might sound crazy, but I ended up hooking up a Seagate 1tb SATA drive via USB3 as it was faster.

In the thunder bay I have a Corseair Force LE 500gb SSD that I have windows 10 installed on and it works really great, so I don't think it's a hardware problem with the TB2 drive bay or cabling. Push comes to shove, I will use the drive in an upcoming Win10 laptop (as I have had not so good luck getting Apple hardware to work reliably)

On the side of the FaceTime camera issue, I think i have isolated it to one of two programs that I bought to monitor the fan speed in the mac and connect my Android phone to the iMac to get SMS messages. I've contacted the developer and am seeing if we can figure out what is wrong.