Re: Speed-optimized file copy
Re: Speed-optimized file copy
- Subject: Re: Speed-optimized file copy
- From: Stevo Brock <email@hidden>
- Date: Tue, 19 Jul 2011 17:53:17 -0700
Hi Eric,
Thanks for chiming in. I was in fact reading your recent thread very closely in preparation for putting this together. In my case, I will also be reading every file off a source disk for processing and copying.
And here's another interesting question - everything we've been talking about so far has assumed spinning media - how do things change if the source and/or destination is Flash-based?
-Stevo
On Jul 19, 2011, at 5:18 PM, email@hidden wrote:
> Quinn wrote:
>
>> On 18 Jul 2011, at 21:25, Stevo Brock wrote:
>
>> > What are ways that we could improve the efficiency of this system?
>>
>> o optimise for seeks
>
> This problem seems very similar to one I posted not to long ago in the thread:
>
> How to read files from disk directly?
> http://lists.apple.com/archives/Filesystem-dev/2011/Jul/msg00000.html
>
> Basically, I needed to do something very similar which was to read every file on disk and process them. In Brock's case, that processing appears to be writing them to multiple locations.
>
> While reading the files from the disk directly is simply not practical, attempting to optimize for seeks did look a bit more reasonable.
>
> One possible method involved using fcntl/F_LOG2PHYS to at least try to determine in which order the start of every file appeared on the disk and then read the files in that order to try to optimise for seeks.
>
> However, the thread forked into another one:
>
> Problem with fcntl/F_LOG2PHYS (was: Re: How to read files from disk directly?)
> http://lists.apple.com/archives/Filesystem-dev/2011/Jul/msg00022.html
>
> and, as best I can determine, this is not very practical either, but perhaps I misinterpreted something.
>
> So, what might the recommendation be if one wanted to optimize for seeks when reading every file in a file system?
>
>
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