Re: [noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Frantisek Rysanek
On 7 Jan 2008 at 13:49, Jörn Engel wrote: > > If you retry the dd with bs=4096 (or whatever your architecture's page > size happens to be), does this still occur? > > JĂśrn > wow, thanks, it works, this is so obvious. I tend to use values like bs=512000 or suchlike, but probably never stroke

Re: [noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Jörn Engel
On Mon, 7 January 2008 13:25:09 +0100, Frantisek Rysanek wrote: > > let me start with a simple example. The following commands: > > cp /dev/zero /dev/hda > dd if=/dev/zero of=/dev/hda [bs=512] > > both have one common side-effect: apart from the disk being properly > overwritten with zeroes,

[noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Frantisek Rysanek
Dear Everyone, let me start with a simple example. The following commands: cp /dev/zero /dev/hda dd if=/dev/zero of=/dev/hda [bs=512] both have one common side-effect: apart from the disk being properly overwritten with zeroes, the kernel seems to keep reading sectors ahead of the current

[noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Frantisek Rysanek
Dear Everyone, let me start with a simple example. The following commands: cp /dev/zero /dev/hda dd if=/dev/zero of=/dev/hda [bs=512] both have one common side-effect: apart from the disk being properly overwritten with zeroes, the kernel seems to keep reading sectors ahead of the current

Re: [noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Jörn Engel
On Mon, 7 January 2008 13:25:09 +0100, Frantisek Rysanek wrote: let me start with a simple example. The following commands: cp /dev/zero /dev/hda dd if=/dev/zero of=/dev/hda [bs=512] both have one common side-effect: apart from the disk being properly overwritten with zeroes, the

Re: [noob q. on block layer] block IO read-ahead during sequential *write*?

2008-01-07 Thread Frantisek Rysanek
On 7 Jan 2008 at 13:49, Jörn Engel wrote: If you retry the dd with bs=4096 (or whatever your architecture's page size happens to be), does this still occur? JĂśrn wow, thanks, it works, this is so obvious. I tend to use values like bs=512000 or suchlike, but probably never stroke this