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When converting large files is it best to write onto another disk?

R

rawdawg

macrumors 6502a
Original poster
Jan 7, 2009
552
112
Brooklyn
I have a 2TB RAID 0 that houses all my video files and such. (My system is on another disk)

Many times I do conversions of very large files (50+gb). Since my RAID 0 is already reading that file it is bad to also have it writing the new file to the same array? Should I have my computer writing to another disk when reading from one?

I thought the RAID array was supposed to easy system woes but this seems like an obvious bottleneck. I haven't experienced any problems with speed when having it read and write to the same drive but I'm worried if it's bad for the array (taxing it to read and write at the same time like that). I do hear the heads clicking rapidly when I've done it in the past. Which is why I've recently been having it write to my system disk when doing these conversions. I then copy the file back to the array. Is this needless concern on my behalf?

Maybe I just don't fully understand how modern systems work.
 
I don't think it's bad for it. By having the input and output files on the same disk, the drive has to read some of the input file, then move to the output file to write. The rapid clicking is the drive heads moving back and forth between the locations of each file. By putting the two files on separate drives, the heads only have to move a little between pieces that are being read or written. This will be faster and put a little less wear on the drive.

I don't think you will notice any difference in speed since video conversion is usually CPU-bound. If you were trying to duplicate a file by copying it and pasting it somewhere else on the same drive, it would be faster if the files were on two drives.
 
It's not a concern in the sense that any drives will become damaged etc. If you are not noticing any speed issues then u have nothing to worry about.

But yes - writing to a separate drive is/was better for older computers with slower data throughput and slower hard drives.
 
its not bad at all. if you are reaching the limits of the I/O of the device then it may be limiting your conversion speeds - you could test that i guess but wont do any damage what so ever.
 
thanks for the input. My bottleneck is the eSATA expresscard interface ~190mb/s. I'm sure my 2 drive RAID 0 is capable of faster speed so I assume I'm well within the comfort zone of not taxing my array.

And if I was sending data out through my expresscard and back out to a new drive via FW800 I was similarly have a new bottleneck with the newer slower FW800. Since eSATA is the fastest I guess I should be fine staying on the same drive.

thanks
 
rawdawg said:
thanks for the input. My bottleneck is the eSATA expresscard interface ~190mb/s. I'm sure my 2 drive RAID 0 is capable of faster speed so I assume I'm well within the comfort zone of not taxing my array.

And if I was sending data out through my expresscard and back out to a new drive via FW800 I was similarly have a new bottleneck with the newer slower FW800. Since eSATA is the fastest I guess I should be fine staying on the same drive.

thanks
Click to expand...

yup all correct there i cannot see anything wrong with that. the transfer speed of the array is all the speeds of the disks added together. not sure of your drives, but assuming they are newish then the eSATA interface would ndeed be your bottleneck - but only by a bit :)
 
YES, use other drive

if you want max. performance, definitely use another drive.

does the enclosure has FW 800 interface ? if so, you can connect another FW drive directly to it daisy-chaining. it will.

reading from one course and writing another makes a big difference if you are after performance. that's what i do.
 
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