Forgot to mention, I've tried the sg_dd program with different bpt values. Like 30,40,60,400,401,257,267. seems like whenever it's even the speeds is faster. --- Ying Li <hellbunni@xxxxxxxxx> wrote: > hi, > > I recently got a seagate cheetah (ST336753FC, 15k.3 > RPM 37GB) harddrive that sits in my JMR Fortra 2G6 > array. > I'm running Linux 2.6, using sg3_util.1.13 > > My seagate is mapped to /dev/sdb > I run the following: > > 1.)time sg_dd if=/dev/zero of=/dev/sdb bpt=256 > count=1200000 > a.) it finishes on average around 10 seconds > > 2.)time sg_dd if=/dev/zero of=/dev/sdb bpt=255 > count=1200000 > a.) this finishes on average around 18 seconds > > Why is there such a big difference? > > In a program that I wrote, > --one pc reads data from one hd > --transfers it over a closed network > --another pc writes the data received to another hd > > When I had both the hd being as seagate cheetah > (ST318453FC, 15k RPM 17GB), I was getting good > overall > (transfer + read/write) speed around 300Mb/s. The > drives sit in the JMR Fortra 2G6 array. But when I > replaced one of these with my new 37GB hd, i get > weird > resuls. > --if the 37GB replaced the one data is written to, > my overall speed drops by a factor of 100Mb/s > --if the 37GB replaced the one data is read off > of, > my overall speed remains at 300Mb/s. > > Any help would be greatly appreciated. THANKS!!! > > -Ying > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam > protection around > http://mail.yahoo.com > __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/ - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
