Thunderbolt Target Disk Mode is Slow

[Pentad]

I don't know if you have read the disappointing articles on Thunderbolt in Target Disk Mode here and here but over the weekend a colleague of mine actually did some testing with two 2011 MBPs and had the same results.

They said the cable warmed up and their transfers were SLOWER than FW800 in Target Disk Mode.

This truly is disappointing. I hope that the issues we are seeing are minor bugs in firmware that can be resolved with an update.

-P

 

[FSMBP]

I don't know if you have read the disappointing articles on Thunderbolt in Target Disk Mode here and here but over the weekend a colleague of mine actually did some testing with two 2011 MBPs and had the same results.

They said the cable warmed up and their transfers were SLOWER than FW800 in Target Disk Mode.

This truly is disappointing. I hope that the issues we are seeing are minor bugs in firmware that can be resolved with an update.

-P

Oh jeez. I'm hoping it's what you said: a firmware issue.

The thing I love about Macs was the Target Disk Mode. I remember copying over my entire Home Folder to my friend's iMac when I need to do a clean restore to my Mac & still keep my files.

 

[317342]

From the OWC Blog..

The FireWire 800 interface theoretically transfers data up to 100MB/s. In real life, peak rates typically are just below 90MB/s. Using Target Disk Mode over FireWire 800, we averaged 40MB/s reads and 38MB/s writes which equates to about 40% of the full capability of the FireWire 800 interface - as is typical with either an SSD or a hard drive in this situation.

Clearly there is some overhead in supporting Target Disk Mode.

By our logic, we figured that since Thunderbolt has a theoretical maximum data transfer rate of 1250MB/s we expected to see about 40% of that speed, or 500MB/s (which our SSD itself is capable of internally – see benchmark below). Unfortunately that wasn’t the case.

Using Target Disk Mode with an SSD over Thunderbolt averaged 74MB/s reads and 49MB/s writes, which was only a mere 4-6% of the full throughput capability that the Thunderbolt interface should be capable of.

It sounds like it's just a hair faster than FW800. We'll probably see some firmware updates in the coming months but for now it works and you're not likely going to use TDM daily (using Apple's logic)

 

[NutsNGum]

I asked a similar question recently relating to thunderbolt TDM and BareFeats explained in a reply that it was likely to be much slower due to Target Disk Mode only using the system's EFI.

I'm not savvy enough to understand completely the difference that this would make, but I'd take his word for it.

 

[Pentad]

I asked a similar question recently relating to thunderbolt TDM and BareFeats explained in a reply that it was likely to be much slower due to Target Disk Mode only using the system's EFI.

I'm not savvy enough to understand completely the difference that this would make, but I'd take his word for it.

That is interesting. I will have to do some research to find out more information on this.

I was hoping that TDM would be a whole lot faster than FW800 to facility larger files/bigger drives.

So far, I have to keep lowering my expectations about TB:

-insanely expensive cable

Ok, I guess I can live with that...

-TDM no better than FW800

Another let down but ok, I can live with that...

-It's July 11 and how many TB devices are there??

I was hoping for more but TB development takes time so I'm sure we'll see more later this year (fingers crossed)...


-PC friends snickering at TB while they backup huge amounts of files to their portable USB3 drives..

So, I feel like Linus, "Just you wait for the Great Pumpkin...I mean TB backup devices! You'll see! Your plethora of affordable-low-power-consuming-standardized-portable-fast backup devices are no match for the insanely-great-expensive-cable-using-non-existence-backup-drives that we are hoping-I mean know will be here by the end of the year! So, yeah!'

-P