On Thursday 30 September 2010, Adam Carter wrote: > Taring my mp3 collection from 2.5in 500MB internal sata drive (sda) to > esata 3.5in 500MB drive (sdb) and it seems slow. In vmstat i can see that > the external drive writes faster than the internal can read (external has > periods of inactivity) > # time tar cf /mnt/usbdrive/mp3back.tar mp3/ > > real 10m9.679s > user 0m1.577s > sys 2m1.769s > # du -ks mp3/ > 21221661 mp3/ > > So 21221MB in 610 seconds = 35 MB/s > > # hdparm -t /dev/sda > > /dev/sda: > Timing buffered disk reads: 220 MB in 3.01 seconds = 73.14 MB/sec (77 > with --direct) > > FWIW; > # hdparm /dev/sda > > /dev/sda: > multcount = 16 (on) > IO_support = 1 (32-bit) > readonly = 0 (off) > readahead = 256 (on) > geometry = 60801/255/63, sectors = 976773168, start = 0 > > > So the should i expect filesystem (reiser3) and other overhead to cut the > read performance to less than half of what hdparm reports? Anything else i > can look at to speed it up? Im using CFQ io scheduler.
as soon as your harddisk seeks you are lucky to be above 5mb/sec. Yes, even with a modern harddrive. Just look up the seek times and do the math. Your harddisk seeks, everything is slow.
