what's the worst that can happen
 

I know Avid recommends 7200 rpm for external drives. I bought the LaCie USB at 5400 rpm for some simple recording on my laptop. Two simultaneous tracks is all I'm recording. Then when I'm done recording, I'll transfer everything to my Glyph at 7200 rpm, where I add other instruments and finally mix. What's the probability I won't have any problems? I'm pretty sure I'll be ok, but was just checking.

Re: what's the worst that can happen
 

2 tracks but at what sample rate? Sample rate is going to be a big factor of how fast the drive needs to write.
Most likely you'll be fine.

But important, before going into any critical recording, is to test. Put the 2 tracks into record and see what happens (even with dead air/no mic connected.) The data amount will be the same. When we go into big record sessions (64 channels, etc.) we'll test the system by having it record for hours and see if it glitches or drops out of record.

(Also, if you are planning to punch-in/drop into record, realize the drive and USB connection also has to handle that which could be the playback of the previous recording. So it can be more than the demands of 2 recording tracks. In that case, it would be 2 playback PLUS 2 recording)

Re: what's the worst that can happen
 

just use disk cache - it's in the PT manual

Re: what's the worst that can happen
 

Thanks for bringing the sample rate up. I was planning on 96 but I could do 48 too. I'll test it out when I get it. Thanks

Re: what's the worst that can happen
 

I'll probably test at 48 kHz and buffer size 512. I'm assuming I won't have any problems. I won't be punching in, either.

Re: what's the worst that can happen
 

I have that very same enclosure. It is good all-around box, but nothing to brag about.

Just a year ago I replaced the drive with SSD, and while the throughput didn't improve (SATA restriction) the latency went down to "nothing".