[PLUG] Confusion with DMA on or off

Sasha Romanosky sasha_romanosky at yahoo.com
Wed Oct 22 01:58:02 UTC 2003


I'm trying to confirm that DMA is enabled on two of my drives and I have
conflicting output from boot up (dmesg) and hdparm. They are relatively
new drives and I'm running mandrake 9.1. See below: 

root at fans[/var/log]# dmesg |egrep "hde|hdf"
    ide2: BM-DMA at 0xdc00-0xdc07, BIOS settings: hde:DMA, hdf:DMA
hde: MAXTOR 6L060J3, ATA DISK drive
hdf: WDC WD1200BB-00DAA3, ATA DISK drive
hde: DMA disabled
hdf: DMA disabled
hde: host protected area => 1
hde: 117266688 sectors (60041 MB) w/1819KiB Cache, CHS=7299/255/63,
UDMA(100)
hdf: host protected area => 1
hdf: 234441648 sectors (120034 MB) w/2048KiB Cache, CHS=14593/255/63,
UDMA(100)


root at fans[/var/log]# hdparm /dev/hde
/dev/hde:
 multcount    = 16 (on)
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 7299/255/63, sectors = 117266688, start = 0

root at fans[/var/log]# hdparm /dev/hdf
/dev/hdf:
 multcount    = 16 (on)
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 14593/255/63, sectors = 234441648, start = 0


I would tend to belive hdparm and if it is, indeed, correct, then I am
puzzled by the "DMA disabled" from dmesg. Any ideas? 

cheers,
sasha



fwiw, here's the output of hdparm -Tt on the two drives:
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hde

/dev/hde:
 Timing buffer-cache reads:   128 MB in  1.48 seconds = 86.49 MB/sec
 Timing buffered disk reads:  64 MB in  2.10 seconds = 30.48 MB/sec
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hde

/dev/hde:
 Timing buffer-cache reads:   128 MB in  1.19 seconds =107.56 MB/sec
 Timing buffered disk reads:  64 MB in  1.78 seconds = 35.96 MB/sec
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hde

/dev/hde:
 Timing buffer-cache reads:   128 MB in  1.35 seconds = 94.81 MB/sec
 Timing buffered disk reads:  64 MB in  2.02 seconds = 31.68 MB/sec
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hdf

/dev/hdf:
 Timing buffer-cache reads:   128 MB in  1.20 seconds =106.67 MB/sec
 Timing buffered disk reads:  64 MB in  1.55 seconds = 41.29 MB/sec
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hdf

/dev/hdf:
 Timing buffer-cache reads:   128 MB in  1.13 seconds =113.27 MB/sec
 Timing buffered disk reads:  64 MB in  1.56 seconds = 41.03 MB/sec
root at fans[/etc/sysconfig/network-scripts]# hdparm -Tt /dev/hdf

/dev/hdf:
 Timing buffer-cache reads:   128 MB in  1.16 seconds =110.34 MB/sec
 Timing buffered disk reads:  64 MB in  1.47 seconds = 43.54 MB/sec






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