Re: [Bug-ddrescue] ddrescue on BSD vs Linux

[Florian Sedivy]

Ola, 

Antonio Diaz Diaz <address@hidden> schreibt am 11.11.2010 18:47 Uhr:

> Ddrescue can use O_DIRECT (option -d), but be aware that "Using direct
> disc access, or reading from a raw device, may be slower than normal
> cached reading for hard discs (but faster for floppies). In this case
> you may want to make a first pass using normal cached reads, and use
> direct disc access, or a raw device, only to recover the good sectors
> inside the failed blocks."

In my experience on Mac OS (which is probably the widest spread BSD variant)
using the raw character special device (/dev/rdiskX) is actually much faster
than using the block device (/dev/diskX) in both reading and writing.

Since I confirmed a difference of up to factor 4 in several tests, I now
always use the raw device.

Thanks for this indispensable tool,
Florian