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View Full Version : OS X Slow @ Copying Multiple Items?



cosmichobo
10th April 2010, 10:50 AM
G'day,

If I select half a dozen items, and drag them to another disc to copy, the copy window identifies 6 items, copies, finishes, yay.

If I do the same with a few items... then whilst it's copying, drag a few more over... it adds another section to the copy window. Lovely. But... is it just me, or does it take longer when you have these 2 groups of items copying, than if you'd either done them all together, or done one, and waited for it to finish before doing the second??

The estimated times to copy seem to jump a lot when you add the second copy batch...

cheers


cosmic

lord
10th April 2010, 12:17 PM
What you are probably seeing here is part of the way a hard drive works.

When copying one file you would see the head move to one location, read data then move to a different location to write it. This would happen over and over with a slight delay while the heads move to the new location.

When copying many files at one time you would see the head move to pick up data from section one, move to section two, write, move to section three, read, move to section 4, write. Repeated many times you would expect a lot of time to be 'wasted' in moving heads around.

Just a total swing in the dark here, but i'd say its something like that - rather than a software issue.

cosmichobo
10th April 2010, 03:04 PM
Sounds like it would be better if the OS actually queued the copying, which I assume it does automatically when you select multiple items... but should then still queue them when you choose multiple batches. Or let you choose to pause the copies.

marc
10th April 2010, 06:56 PM
Sounds like it would be better if the OS actually queued the copying, which I assume it does automatically when you select multiple items... but should then still queue them when you choose multiple batches. Or let you choose to pause the copies.

Sure, but there's a complication. If you're copying from and to different drives, then they can be done in parallel.

A case where queuing would be bad: You start a large transfer to a wireless network drive. It'll take hours to complete, then you start a small transfer to an internal drive.

davedave
10th April 2010, 09:46 PM
G'day,

If I select half a dozen items, and drag them to another disc to copy, the copy window identifies 6 items, copies, finishes, yay.

If I do the same with a few items... then whilst it's copying, drag a few more over... it adds another section to the copy window. Lovely. But... is it just me, or does it take longer when you have these 2 groups of items copying, than if you'd either done them all together, or done one, and waited for it to finish before doing the second??

The estimated times to copy seem to jump a lot when you add the second copy batch...

cheers


cosmic

I experience the same thing. It can make the copy function a little painful. I probably shouldn't say this, but, windows does seem to be a little more efficient in this department with respect to speed.

lord
10th April 2010, 10:06 PM
Sure, but there's a complication. If you're copying from and to different drives, then they can be done in parallel.

This i've found is not this case with flash based memory, still correct of course though!

Flash it seems is good with large singular files, but falls over its feet when presented with a large number of smaller files. I can't work out why that is though.

bennyling
10th April 2010, 10:15 PM
Flash it seems is good with large singular files, but falls over its feet when presented with a large number of smaller files. I can't work out why that is though.

It's to do with the underlying technology of flash and it's controllers.

Flash controllers can be "geared" to be really good at sequential writes, but sacrifice random/smaller writes for that speed.

For people who use their SSDs as boot drives, random reads/writes all over the disk are what make an SSD seem "slow" - even though you can get 270MB/s sequential read, your random 4K reads will be roughly a hundredth of that (depending on which SSD you buy, of course), and random reads/writes being what an OS does the most (you'll rarely see huge sequential reads/writes in typic OS usage), having a really good SSD that does random reads/writes really well (and still posts decent sequential speeds as well) is paramount to a fast, responsive system.

cosmichobo
10th April 2010, 10:18 PM
Windows is a pita. Ok, not so sure about copying... but moving a file - seems to be treated like copying - takes FOREVER. Whereas, move a file in Mac, and it's done.