I added a Maxtor 27GB 7200rpm ATA66 drive to my P200MMX when I upgraded to potatos and kernel 2.2.14.
My motherboard (ASUS TX97-E) only supports udma mode 2 (33MB/sec), but I find that this drive and my old WD 4GB (no UDMA) both show the same speed of about 9.4MB/sec with hdparm -t. Even if the new drive is the only drive on the primary IDE interface. All the boot messages and hdparm info seems to indicate that the UDMA-2 is recognized, but why don't I see any speed difference? Here is the output of hdparm -v -i for both drives: /dev/hda: (MAXTOR 27GB, UDMA) multcount = 0 (off) I/O support = 0 (default 16-bit) unmaskirq = 0 (off) using_dma = 1 (on) keepsettings = 0 (off) nowerr = 0 (off) readonly = 0 (off) readahead = 8 (on) geometry = 3322/255/63, sectors = 53369568, start = 0 Model=Maxtor 92732U8, FwRev=RA530JN0, SerialNo=H8059G4C Config={ Fixed } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57 BuffType=3(DualPortCache), BuffSize=2048kB, MaxMultSect=16, MultSect=off DblWordIO=no, OldPIO=2, DMA=yes, OldDMA=0 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=53369568 tDMA={min:120,rec:120}, DMA modes: mword0 mword1 mword2 IORDY=on/off, tPIO={min:120,w/IORDY:120}, PIO modes: mode3 mode4 UDMA modes: mode0 mode1 *mode2 mode3 mode4 /dev/hdb: (WD 4GB, no UDMA) multcount = 0 (off) I/O support = 0 (default 16-bit) unmaskirq = 0 (off) using_dma = 1 (on) keepsettings = 0 (off) nowerr = 0 (off) readonly = 0 (off) readahead = 8 (on) geometry = 969/128/63, sectors = 7814016, start = 0 Model=WDC AC34000L, FwRev=24.39E26, SerialNo=WD-WT3510356735 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq } RawCHS=7752/16/63, TrkSize=57600, SectSize=600, ECCbytes=22 BuffType=3(DualPortCache), BuffSize=256kB, MaxMultSect=16, MultSect=off DblWordIO=no, OldPIO=2, DMA=yes, OldDMA=0 CurCHS=7752/16/63, CurSects=7814016, LBA=yes, LBAsects=7814016 tDMA={min:120,rec:120}, DMA modes: mword0 mword1 *mword2 IORDY=on/off, tPIO={min:160,w/IORDY:120}, PIO modes: mode3 mode4 ...RickM...