Re: device timings
Modern disks pack different ammounts of data on different tracks.. (the outside tracks are longer right?) so at a constant speed (rpm) outside tracks have more data passing below the head per given time than teh inside tracks do... this seems pretty normal to me.. Marc Tardif wrote: > > Considering the following disk configuration: > *** Working on device /dev/rwd0 *** > parameters extracted from in-core disklabel are: > cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl) > > parameters to be used for BIOS calculations are: > cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl) > > Media sector size is 512 > Warning: BIOS sector numbering starts with sector 1 > Information from DOS bootblock is: > The data for partition 1 is: > sysid 165,(FreeBSD/NetBSD/386BSD) > start 63, size 1937565 (946 Meg), flag 80 (active) > beg: cyl 0/ sector 1/ head 1; > end: cyl 232/ sector 63/ head 131 > The data for partition 2 is: > sysid 0,(unused) > start 1937628, size 58212 (28 Meg), flag 0 > beg: cyl 233/ sector 1/ head 0; > end: cyl 239/ sector 63/ head 131 > ... > > Now considering the following timings done with dd, how come I get such > different transfer rates (bytes/sec) for s1 and s2? I understand there > should be a difference between the block and character interface, as shown > in the first two timings, but why isn't the same difference shown for the > last two timings? > > # dd if=/dev/wd0s1 of=/dev/null bs=8316b count=5 > 5+0 records in > 5+0 records out > 21288960 bytes transferred in 8.580486 secs (2481090 bytes/sec) > > # dd if=/dev/rwd0s1 of=/dev/null bs=8316b count=5 > 5+0 records in > 5+0 records out > 21288960 bytes transferred in 4.058639 secs (5245344 bytes/sec) > > # dd if=/dev/wd0s2 of=/dev/null bs=8316b count=5 > 5+0 records in > 5+0 records out > 21288960 bytes transferred in 6.066568 secs (3509226 bytes/sec) > > # dd if=/dev/rwd0s2 of=/dev/null bs=8316b count=5 > 5+0 records in > 5+0 records out > 21288960 bytes transferred in 6.015735 secs (3538879 bytes/sec) > > To Unsubscribe: send mail to [EMAIL PROTECTED] > with "unsubscribe freebsd-fs" in the body of the message -- __--_|\ Julian Elischer / \ [EMAIL PROTECTED] ( OZ) World tour 2000 ---> X_.---._/ presently in: Perth v To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: device timings
In message <[EMAIL PROTECTED]>, Marc Tard if writes: >Now considering the following timings done with dd, how come I get such >different transfer rates (bytes/sec) for s1 and s2? I understand there >should be a difference between the block and character interface, as shown >in the first two timings, but why isn't the same difference shown for the >last two timings? Because all modern disks use "zone-layout" where there are typically 50% more sectors in the outher cylinders compared to the inner cylinders. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
device timings
Considering the following disk configuration: *** Working on device /dev/rwd0 *** parameters extracted from in-core disklabel are: cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl) parameters to be used for BIOS calculations are: cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl) Media sector size is 512 Warning: BIOS sector numbering starts with sector 1 Information from DOS bootblock is: The data for partition 1 is: sysid 165,(FreeBSD/NetBSD/386BSD) start 63, size 1937565 (946 Meg), flag 80 (active) beg: cyl 0/ sector 1/ head 1; end: cyl 232/ sector 63/ head 131 The data for partition 2 is: sysid 0,(unused) start 1937628, size 58212 (28 Meg), flag 0 beg: cyl 233/ sector 1/ head 0; end: cyl 239/ sector 63/ head 131 ... Now considering the following timings done with dd, how come I get such different transfer rates (bytes/sec) for s1 and s2? I understand there should be a difference between the block and character interface, as shown in the first two timings, but why isn't the same difference shown for the last two timings? # dd if=/dev/wd0s1 of=/dev/null bs=8316b count=5 5+0 records in 5+0 records out 21288960 bytes transferred in 8.580486 secs (2481090 bytes/sec) # dd if=/dev/rwd0s1 of=/dev/null bs=8316b count=5 5+0 records in 5+0 records out 21288960 bytes transferred in 4.058639 secs (5245344 bytes/sec) # dd if=/dev/wd0s2 of=/dev/null bs=8316b count=5 5+0 records in 5+0 records out 21288960 bytes transferred in 6.066568 secs (3509226 bytes/sec) # dd if=/dev/rwd0s2 of=/dev/null bs=8316b count=5 5+0 records in 5+0 records out 21288960 bytes transferred in 6.015735 secs (3538879 bytes/sec) To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
