new to the forums-- question about time

[poetrydaze]

I've searched for a ball-park answer on this, but can't find it.

How long should it take for my iMac '08 2.66G with about 80gigs of data to clone via firewire to a Lacie drive?

I just am curious about a ballpark. And can I use the computer while the clone is taking place?

Thanks Dan

[dnanian]

An Intel should run at about 8-12MB/s, assuming things are going well. You can lightly use the computer, but don't run VMWare/Parallels/Entourage/etc... things with big data files. Don't download, don't run iTunes...

[poetrydaze]

dnaanian. THANKS so much for your quick reply. Forgive my ignorance... but I'm terrible with math. 8-12MB/s would translate to about how long for 80gigs of data?

Again, sorry to be such a *newbie* but I've not done this before. Thank you in advance. Dan

[dnanian]

Dan, I think you can handle the math involed here -- it'll give you something to do while you're waiting for the copy to complete.

[poetrydaze]

Actually Dave. I was being quite serious. Honestly, I didn't mean to come off as a dunce. So let me run my math by you and see if I'm correct. If I use 8M/s as a standard tha would mean 480m in a minute... so about one Gig every two minutes. So 80 times two equals 160 minutes? Am I close. I'm serious! I'm terrible with the math. I guess I was just asking the simple question. How many hours would 80gigs take. I suppose I should have phrased it differently. Thanks, Dan

[dnanian]

There you go: close enough. But again - it's a guesstimate.

[DEinspanjer]

Originally Posted by dnanian

An Intel should run at about 8-12MB/s, assuming things are going well. You can lightly use the computer, but don't run VMWare/Parallels/Entourage/etc... things with big data files. Don't download, don't run iTunes...

Sorry to dig up an old thread, but this question and answer was exactly what I was searching for.

I just did a fresh clone of my MBP and was getting between 8 to 12 MiB/s as the typical value displayed in the progress dialog. When it finished, it reported the effective rate was 20MiB/s. I'm assuming that might have been due to small files that it blew through at the end or something.

My follow up question is sorta "why?". I'm using Firewire 800, it is theoretically rated at 800 megabits/s which would theoretically mean 100 megabytes/s. Was it a waste to get something rated at 100 MB/s if I'm ever only going to see 12 MB/s? Is there some optimal circumstance that I could see significantly better transfer rates? I was hoping to cut my backup time in half by upgrading from USB2 to FW800 and that doesn't appear to be possible.

[dnanian]

Welcome to the difference between "specifications" and "real world performance".

100MB/s is the maximum "wire" speed. Now, layer protocols on top, and then do something other than just straight data streaming, with an OS, small file I/O, etc. You're just not going to get anything close to 100MB/s copying lots of small files, or even straight-up streaming to and from drives.

[chris_johnsen]

Also, besides the interconnect speed, you have to consider the drives.

Putting a drive that can not manage to “soak” a FW400 connection in an FW800 enclosure will not make it any faster. You would likely need at least a 7200 RPM (or even a 10000 RPM drive) to make the best possible use of the FW800 connection. Hopefully manufacturers would not sell FW800 enclosures with “poky” drives, but you never know.

Plus, when you are doing a copy operation (like using SuperDuper!) you must consider both the source and the destination drive (usually one is your internal disk). Since laptop drives are generally designed to save power they are often slower. When copying to/from an internal laptop HD from/to an external FW800 drive, the most likely bottleneck is your internal drive.

As a subjective test, you might try booting off of your FW800 drive. For a time I was running my iBook (originally with a 4200RPM internal, later with a 5400 RPM internal) off of an external FW400 7200RPM drive. The system was noticeably faster using the external, especially when the system started using virtual memory.