Re: disk vs rdisk, was: How to obtain the FAT serial number form a volume
Re: disk vs rdisk, was: How to obtain the FAT serial number form a volume
- Subject: Re: disk vs rdisk, was: How to obtain the FAT serial number form a volume
- From: Chris Suter <email@hidden>
- Date: Fri, 02 Mar 2012 10:11:11 +1100
Hi Mark,
On Thu, Mar 1, 2012 at 12:49 PM, Mark Day <email@hidden> wrote:
> The caching being done by /dev/disk's read and write paths is very simple,
> almost brain dead. It caches even if not strictly necessary (like if the
> device could memory map and directly transfer into your app's buffer). It
> does small (4KB) I/Os, which leads to a lot of per-I/O overhead. It does
> not do any read ahead or write behind.
Are you sure about that? It looks like there's a read-ahead of 1 block
and it uses write behind.
Kind regards,
Chris
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