External scratch disc for new iMac?

Flashman

Flashman

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Keith
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I'm going to order a new iMac when they are released and, as far as I can tell, you can only spec one internal drive (I will prolly go for the SSD rather than the fusion drive... depending on price). I've never really wrapped my head around the ideal way to set up and allocate scratch discs for Photoshop so was wondering if anyone could tell me if the following is a good solution, or if it is even necessary...

I was thinking about getting an external thunderbolt SSD to use solely as a dedicated scratch disc. Is this a good solution? If so, is 120Gb big enough???
 
you can pop a hard drive where the DVD is if you dont use that.

thunderbolt would be a nice fast solution (even FW800 should be okay), i dont think youll need more than 120 to be honest.
 
what's a scratch disk?
 
neil_g said:
you can pop a hard drive where the DVD is if you dont use that.

thunderbolt would be a nice fast solution (even FW800 should be okay), i dont think youll need more than 120 to be honest.
Click to expand...

Thanks Neil. They're not putting optical drives in any more so I guess the DVD slot option is out, they've dropped Firewire too. So a 120Gb Thunderbolt jobbie sounds like the best solution. Appreciate the input! :)
 
neil_g said:
id be tempted to wait then and see if you need a scratch at all. ive got 16gb in my PC with CS4 and it doesnt need one (or at least what I do doesnt).
Click to expand...

Ah OK... I just assumed it was a necessity. I'll hold off until I've got it set up then and see how it goes. Thanks!
 
neil_g said:
it should only scratch once it runs out of memory, so you may be okay with the main disk set as the scratch (but not being used if you get my drift)
Click to expand...

So if I had several huge D800 images open in PS at the same time is that likely to overflow 32GB of RAM?
 
The rule of thumb that I use with Photoshop since back in the early 90s is to have available RAM five times the size of file(s) that you're working on to avoid hitting scratch.

Use the uncompressed file size reported at the bottom left of a PS window for calculations.

32 GB ought to give you plenty of room for manoeuvre, though.
 
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Musicman said:
The rule of thumb that I use with Photoshop since back in the early 90s is to have available RAM five times the size of file(s) that you're working on to avoid hitting scratch.

Use the uncompressed file size reported at the bottom left of a PS window for calculations.

32 GB ought to give you plenty of room for manoeuvre, though.
Click to expand...


Thanks Rob. A typical image is reading 'Doc:206.9M/206.9M' so I guess there'll be loads of headroom. :thumbs:
 
16 gb is enough at the moment. I think if you open more files soft will still use temporary disk space for storage. 32 gb is more for video editing or 3d and CAD. The best trick is to use outstanding memory as a hard disk. The fastest solution. Imagime hard drive fast as memory. Get 32 and use 16gb for disk. The only problem us that you have to do it everytime your comp is restarted. All profi studios are using this method
 
neil_g said:
you can pop a hard drive where the DVD is if you dont use that.

thunderbolt would be a nice fast solution (even FW800 should be okay), i dont think youll need more than 120 to be honest.
Click to expand...

Just got a USB2/FW800 external backup that you can use with 'option Thunderbolt kit'. Sharp intake of breath and admiration for the FW800 when I saw the cost. It may be fast, but it is real expensive.
 
Keith

Mac's come with a little app called Activity Monitor. It will monitor, in real time CPU usage, Network traffic, disk usage, and memory usage. You can use it to see how much memory is being used . As a test I opened Photoshop and loaded 8 x 61 Mb files. Total memory usage, was around 4Gb. so 16 Gb should be more than enough .

As far as backups are concerned the new mac's will come with USB 3 not USB 2 ports , so you should be able to get a fast drive without the cost. Would be nice if Thunderbolts came down in price though
 
Bit of a thread high jack but on similar lines. I was thinking of just specifying an SSD and either an external Thunderbolt or USB 3 HDD will either of those be as quick as an internal hard drive? Thinking about image and video editing. I would go for a fusion drive but 1tb isn't enough and you can't run Bootcamp on a 3tb.
 
Thunderbolt is, in theory, faster than SATA III: TB is 10 Gbps per channel, SATA III is 6 Gbps.

Where you're likely to hit bottlenecks, though, are in the drive itself, and in the bridge chip from the SATA controller in the drive enclosure, translating to Thunderbolt.

SSD/High speed magnetic disk and/or RAID would get you closer to saturating the Thunderbolt connection.

USB 3 comes in at a theoretical max speed of 5Gbps. However, for various reasons, USB tends not to perform so well for sustained transfer rates.

Then again, if you have 5400 rpm internal drive specified on a MacBook, Mac Mini or iMac, you stand a chance of it being faster whatever, though you have to be careful with the exact configuration of the drives(s) you're attaching to the bus to obtain optimum performance. The interface is no magic bullet.

It is certainly approaching the point where these external buses offer relatively cheap access to performance on a par with internal SATA.
 
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