Re: dummy scsi read or scsi command periodically for external USB Hard Disk

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On Tue, Jul 08, 2014 at 12:15:54AM +0800, loody wrote:
> so sg_read will not hammer on the page cache like dd without "iflags=direct"
> 
> thanks for your kind help,

The sg_read program (and other programs in sg3_utils) sends a command directly
to the device using an SG_IO ioctl. This bypasses all the caching layers in
the kernel and always results in IO to the device (if it succeeds).

Regards,
Bryn.

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