Re: How to read files from disk directly?
Re: How to read files from disk directly?
- Subject: Re: How to read files from disk directly?
- From: Toby Thain <email@hidden>
- Date: Mon, 04 Jul 2011 19:51:19 -0400
On 04/07/11 7:07 PM, Eric Gorr wrote:
> What I know is that I can read a single 4gb file in about 3 minutes. It takes around 20-25 minutes to read 4gb spread among 190,000 files.
>
That's actually a much smaller ratio than I'd have guessed, so HFS+ must
be doing something right :)
--Toby
> I do not know for sure what the true bottleneck is, only that reading the same amount of data over a lot of files takes a lot longer.
>
> If I create a DMG from a folder using Disk Utility, will it offer the same benefit as a freshly formatted filesystem?
>
> On Jul 4, 2011, at 11:57 AM, Shantonu Sen wrote:
>
>> Have you proven that seek penalty is your bottleneck?
>>
>> For example, if you copy a filesystem hierarchy to a freshly formatted filesystem, the files will be allocated on disk in the order you copied them. After rebooting (to remove caching effects), if you process every file in the target filesystem in the same order that you copied them, what is the performance?
>>
>> Also note that access the raw device in a coherent fashion requires unmounting the filesystem, which might make such a solution unviable depending on your use case.
>
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Filesystem-dev mailing list (email@hidden)
> Help/Unsubscribe/Update your Subscription:
>
> This email sent to email@hidden
>
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Filesystem-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden