TRIM Support on a SSD in a USB 3 Enclosure

A SSD in any type of external enclosure is basically wasting the speed of the SSD. The best thing to do is put it in a Thunderbolt enclosure but even then TB is much slower than the internal SATA connections.

Most all new SSDs now have Garbage collection. Although not as good as using both TRIM along with the built in G collection it is better than nothing.

Do you mean your current HDD in an external enclosure or the one inside your system, the internal HDD?

It will not be as fast as the internal HDD. Maybe if the internal is a 5400RPM model and you put a SSD or fast 7200RPM drive in a TB enclosure it will be faster than your internal drive.

That 450mbs is Mega bits a second. bits verses Bytes, 8 bits to a Byte. So divid that 450 by 8 = 56.25. And that is not Real World Speed. The fastest I have ever had any USB 2 drive is somewhere aroung 35MBs (That's Mega Bytes. Small b = bits, Cap B = Bytes)

Your internal drive is running at 65 Mega BYTES (MB) a second.

Yes USB 3 will be faster than that 450Mbs.

That is Best Case speed. You won't see that in the real world.

Not correct. An SSD in a USB3 enclosure running a 1052 or greater chip will provide speeds very close to internal speeds. I have both running. My Samsung in an external USB enclosure runs ~400 MB/s and inside runs 420. Cannot complain. I run with trim on for both internal and external SSD's and no issues although not sure it is really required.

What ever drive you boot from you can have trim enabled. I downloaded trim enabler (freeware) and it works fine. Just be sure it is loaded on your external drive. If you want a small fast enclosure look at OYEN Digital Minipro enclosure. It comes in various configurations. Mine has USB3 and FW800 port. It is USB powered (also comes with power supply). It has the latest USB3 chip making it very fast. I also use a dock made by Utechsmart that slso is just as fast if you want one that is a quick change design. I use both a Samsung 500GB EVO SSD and OCZ 512GB SSD. Both have worked very well. Note that a smaller SSD may have slower R/W speeds. Note that USB3 enclosures are not all the same. If it does not have the latest onboard chip it will not provide the fast speeds associated with SSD's. I believe the latest chip is a 1053xx something.

Here is an example of a USB3 enclosure that will support SSD speeds:

http://www.amazon.com/dp/B003VKTJGW/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&coli d=16WHQQ1HVMSYP&coliid=I3ILBGHOZ5JA43

or better yet:

http://www.amazon.com/MiniPro-FireWire-External-Enclosure-Silver/dp/B00655YT9C/r ef=sr_1_3?s=electronics&ie=UTF8&qid=1398558272&sr=1-3&keywords=minipro+enclosure

I have to differ with this statement. I have an external 250Gig SSD drive in a USB3 enclosure as a start up disc on my 2013 27" iMac running Mavericks.

Doing a Disk Speed Test the SSD is returning 220MB/s write and 250MB/s read speed. The internal Mac HDD is running at 74MB/s read and 87MB/s write.

The start up time has reduced from 90sec to 32sec. I have found this to be a very worthwhile exercise. Unfortunately Trim does not appear to be working on the external SSD.

Hello,

You are correct and incorrect. At the time you wrote the solution, the statement s were valid. There is something called UASP (Specific to USB 3.0 and higher) that has been around since 2011/2012. It was only in the latter part of 2015 that you began to see it incorporated in all sorts of USB enclosures and devices. It's even in a cheap $11 case I bought at a retail shop.

UASP is Universal Attached SCSI Protocol. It allows for better management of data transfer over USB for devices with frequent constant I/O. Some people may think I am referring to attaching a SCSI device to a USB. Not quite. SCSI is parallel and ancient but it had a superior method of handling data reads and writes with queue depth storage. It takes USB and adds SCSI protocol on top of it giving your USB device access to SCSI commands on the controller thus increasing performance, latency, throughput, while reducing CPU overhead.

Can your USB truly get 5Gbps ? Well, the answer is pretty much "With UASP it's common to see 4.8Gbps. In some situations you can event get 4.999999Gbps. In rare cases it can even surpass 5.0+ Gbps giving you near SATA 6 speeds". I thought it was tripe until I saw it with my own eyes. There are drawbacks with any technology. Technically TRIM is possible now because you can send those commands through to the device. I've been unable to get it to work but that is an OS issue.

Mac OS X 10.8 added this feature in the IOUSBMassStorage extension. Windows 8.1 and higher have it. Linux just added it.

The only question I can't answer is UASP with USB RAID devices. I hear mixed answers about this combination. So far the answer is, "They don't exist". Yet I have seen it advertised recently. I haven't been able to confirm if its true or false advertising. That's only with the any combination of USB 3.0 w/RAID or w/eSATA+RAID.

I added my two cents on the solution. It was true at one time but that has now changed.