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Questions about external SSD via thunderbolt

stevefo

stevefo

macrumors regular
Original poster
Mar 16, 2013
187
38
What's the best recommendation to boot Mountain Lion from external SSD via thunderbolt?

Are there wake issues from sleep?
Is TRIM supported or even recommended?
Can I make it default boot from external SSD without choosing?
Have there been any reported issues at all booting Mountain Lion from external SSD via thunderbolt?

I was looking at getting a backpack shelf for the back of the iMac or even fabricating one to hold an SSD. So it's not visable. I decided that I don't want to open up my 2012 iMac 27" to add an SSD. That's why I'm going external.

I've read several different threads on this and just wanted some user experience from people that have done this to the 2012 27" iMac.
 
stevefo said:
What's the best recommendation to boot Mountain Lion from external SSD via thunderbolt?

Are there wake issues from sleep?
Is TRIM supported or even recommended?
Can I make it default boot from external SSD without choosing?
Have there been any reported issues at all booting Mountain Lion from external SSD via thunderbolt?
Click to expand...
I use a Buffalo MiniStation Thunderbolt. I removed the factory HDD and replaced it with a 256GB 840 Pro. My experiences:
1) No issues waking from sleep
2) TRIM is supported (not supported on USB 3.0) and AFAIK, is still needed
3) To make it the default drive, I had to go into Preferences --> Startup Disk and select it
4) I don't know about "any reported issues" but I've had none

It works great, is super fast, and dead quiet. Taking apart the Buffalo was even easy... a minute or so with a heat gun (hair dryer would work too) and then pry it apart. A few screws to undo, replace with SSD and put it back together. About 5 minutes total.
 
Nuke61 said:
I use a Buffalo MiniStation Thunderbolt. I removed the factory HDD and replaced it with a 256GB 840 Pro. My experiences:
1) No issues waking from sleep
2) TRIM is supported (not supported on USB 3.0) and AFAIK, is still needed
3) To make it the default drive, I had to go into Preferences --> Startup Disk and select it
4) I don't know about "any reported issues" but I've had none

It works great, is super fast, and dead quiet. Taking apart the Buffalo was even easy... a minute or so with a heat gun (hair dryer would work too) and then pry it apart. A few screws to undo, replace with SSD and put it back together. About 5 minutes total.
Click to expand...

Very interested in this indeed! It's powered off the Thunderbolt port is what I wanted. I'm eventually going to get a Samsung 256GB Pro. Do you have some pictures of yours?
 
stevefo said:
Very interested in this indeed! It's powered off the Thunderbolt port is what I wanted. I'm eventually going to get a Samsung 256GB Pro. Do you have some pictures of yours?
Click to expand...
No pictures of mine, but here's some that I found using Google:
Picture of one apart, with bottom section on left, drive and top on right. The drive is screwed into the top part, and sticky tape holds the bottom of the drive to the case bottom. Heating the underside of the enclosure makes taking it apart easy.
BuffaloMiniStationThunderbolt-2480.jpg


Sitting next to a MBP, very much looking like, IMO, that it could be an Apple product. It also has a USB 3.0 port, but I use the TB connection.
StorageReview-Buffalo-MiniStation-Thunderbolt.jpg
 
Nuke61 said:
No pictures of mine, but here's some that I found using Google:
Picture of one apart, with bottom section on left, drive and top on right. The drive is screwed into the top part, and sticky tape holds the bottom of the drive to the case bottom. Heating the underside of the enclosure makes taking it apart easy.
Image

Sitting next to a MBP, very much looking like, IMO, that it could be an Apple product. It also has a USB 3.0 port, but I use the TB connection.
Image[/QUO

This is my next upgrade for sure. Thanks for the description and finding the pictures.
Click to expand...
 
i've just done it from usb3.0. samsung 840 in a thermaltake case. my thread is on first page have a look.

Its getting near full speeds.

1/4 of the cost of a thunderbold case as well
 
trustever said:
Any particular reason why Trim does not work on USB 3? thanks
Click to expand...
AFAIK, the TRIM command is supported at the IDE and AHCI driver level and simply not supported on external devices. Since Thunderbolt is an extension of the PCI bus, as far as the OS is concerned it's an internal drive.

There might be a workaround for this limitation on Windows or Linux, but on OS X a USB 3.0 drive does not support TRIM. As a workaround, you could get an SSD that has its own garbage collection routine. The worst case is that over time the write performance will get worse, but you might not ever notice it.
 
Nuke61 said:
AFAIK, the TRIM command is supported at the IDE and AHCI driver level and simply not supported on external devices. Since Thunderbolt is an extension of the PCI bus, as far as the OS is concerned it's an internal drive.

There might be a workaround for this limitation on Windows or Linux, but on OS X a USB 3.0 drive does not support TRIM. As a workaround, you could get an SSD that has its own garbage collection routine. The worst case is that over time the write performance will get worse, but you might not ever notice it.
Click to expand...

@ Nuke16 thanks for the impressive explanation, I was wondering if that was the case of his particular caddy but is not the case. Which SSD will have it's own garabage collection ruotine as tunderbolt caddys have an insane cost and I would rather put to good use a USB3 door...
 
crucial m4 does and so do the samsung 840 series

Samsung included wear-leveling and auto garbage collection in the 840 Series, as well as AES 256-bit encryption, TRIM support, S.M.A.R.T. support, and WWN support
 
Just keep in mind that anything over 256GB i.e. 512GB would need to be AC powered as bus does not provide enough power and would not work.
 
stevefo said:
Why would a bigger SSD require more power?
Click to expand...

I can't tell you the technical reason behind it but someone here tried and it does not work. It might have to do with the power requirements. The largest capacity for running external SSD on bus power only is 256GB. You can do a search or perhaps those that have tried can chime in. If you want to give it a go, it might be a very expensive experiment.

EDIT:

found the thread: https://forums.macrumors.com/threads/1526092/
 
Last edited:
Outrigger said:
I can't tell you the technical reason behind it but someone here tried and it does not work. It might have to do with the power requirements. The largest capacity for running external SSD on bus power only is 256GB. You can do a search or perhaps those that have tried can chime in. If you want to give it a go, it might be a very expensive experiment.

EDIT:

found the thread: https://forums.macrumors.com/threads/1526092/
Click to expand...

This is correct. I tried a 500gb 840 in a segate go flex usb 3 caddy and had problems.
 
Outrigger said:
I can't tell you the technical reason behind it but someone here tried and it does not work. It might have to do with the power requirements. The largest capacity for running external SSD on bus power only is 256GB.
Click to expand...

I don't think it's a size issue, but a power issue. Given that the 512GB 840 Pro uses the same amount of power as the 256GB 830, and the Samsung 830 has been sucessfully used in bus powered external enclosures... the 512GB Pro should work too. But as you said, it could be a relatively expensive failed experiment. I only have ~200GB on my entire Fusion drive, so 256GB drives work perfectly for me, but I'd still like to know if a 512GB Pro actually works in a bus powered TB enclosure.
samsung_ssd_840_pro_512gb_power_values.png

http://www.storagereview.com/samsung_ssd_840_pro_review
 
Outrigger said:
Just keep in mind that anything over 256GB i.e. 512GB would need to be AC powered as bus does not provide enough power and would not work.
Click to expand...

You're right, I remember reading that tread below and forgetting compleately about... thanks for bringing that up agian..
 
trustever said:
@ Nuke16 thanks for the impressive explanation, I was wondering if that was the case of his particular caddy but is not the case. Which SSD will have it's own garabage collection ruotine as tunderbolt caddys have an insane cost and I would rather put to good use a USB3 door...
Click to expand...

There is no SSD sold today that dies not have internal garbage collection. The Sandforce controller based drives seem to have more aggressive garbage collection, so you might look for one for those.
 
Weaselboy said:
There is no SSD sold today that dies not have internal garbage collection. The Sandforce controller based drives seem to have more aggressive garbage collection, so you might look for one for those.
Click to expand...

Thanks Weaselboy, I think that I will go for the internal solution swapping out the HDD as 256 could be too small to hodling everything.
Now the question is will I have the guts to do it myself or shall I ask a AASP? and the cash back on the samsung is quite tempting at the moment..
 
Nuke61 said:
I use a Buffalo MiniStation Thunderbolt. I removed the factory HDD and replaced it with a 256GB 840 Pro. My experiences:
1) No issues waking from sleep
2) TRIM is supported (not supported on USB 3.0) and AFAIK, is still needed
3) To make it the default drive, I had to go into Preferences --> Startup Disk and select it
4) I don't know about "any reported issues" but I've had none

It works great, is super fast, and dead quiet. Taking apart the Buffalo was even easy... a minute or so with a heat gun (hair dryer would work too) and then pry it apart. A few screws to undo, replace with SSD and put it back together. About 5 minutes total.
Click to expand...
what read and write speeds are you getting with this setup im very intrested in getting your exact setup
 
trustever said:
Thanks Weaselboy, I think that I will go for the internal solution swapping out the HDD as 256 could be too small to hodling everything.
Now the question is will I have the guts to do it myself or shall I ask a AASP? and the cash back on the samsung is quite tempting at the moment..
Click to expand...

What are you planning to put on it?

Mine only uses 60GB of my SSD with loads of apps and a few games installed.

You move your home directory appart from applications onto the internal HDD and then create alias links to those.
 
passey said:
What are you planning to put on it?

Mine only uses 60GB of my SSD with loads of apps and a few games installed.

You move your home directory appart from applications onto the internal HDD and then create alias links to those.
Click to expand...

well if I only have to put the OS with the apps I barely use 35GB, my idea was to have also the data on the SSD for a faster access and use..

I still have to make up my mind...
 
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