How fast should my hard disk go?

[Paul Furness <paul.furness@vil.ite.mee.com>]

Hello.

I have been having performance issues on several systems running,
variously, RedHat 7.3, RedHat 9, Slackware and Debian. Everythign was
jerky and any copying froze the system for ages. Since this is a dual
2600 CPU with 1G of memory, it was obviously not just a slow machine. 

Further investigation showed that the hard disk was crawling - typically
2.8 MB/sec were being reported by hdparm.

I added the line "idebus=66" to the kernel boot params, and this has
made a big difference. However, I'm not convinced that it's working as
fast as it should. It might be that I don't understand how IDE disk
speed is measured, so I'm hoping that someone who does can explain to me
exactly what is happening.

I have a 133 speed hard disk connected to a 133 controller. I believe
that this should mean that I get a maximum transfer rate of 133 MB/sec?
The disk has an 8M cache on it, which is also supposed to make it
faster. So why am I getting speeds of just under 50MB/sec? Is this
correct (because the max transfer is only in one direction or
something), or am I missing an obvious setting?
 
hdparm supplied info is below.

Will it go faster?! :)

Thanks.

Paul.


Zebra# hdparm -t /dev/hda

/dev/hda:
 Timing buffered disk reads:  64 MB in  1.35 seconds = 47.41 MB/sec

Zebra# hdparm /dev/hda

/dev/hda:
 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     = 238216/16/63, sectors = 240121728, start = 0

Zebra# hdparm -I /dev/hda

/dev/hda:

ATA device, with non-removable media
        Model Number:       Maxtor 6Y120L0
        Serial Number:      Y40K7V5E
        Firmware Revision:  YAR41VW0
Standards:
        Supported: 7 6 5 4
        Likely used: 7
Configuration:
        Logical         max     current
        cylinders       16383   16383
        heads           16      16
        sectors/track   63      63
        --
        CHS current addressable sectors:   16514064
        LBA    user addressable sectors:  240121728
        device size with M = 1024*1024:      117246 MBytes
        device size with M = 1000*1000:      122942 MBytes (122 GB)
Capabilities:
        LBA, IORDY(can be disabled)
        Queue depth: 1
        Standby timer values: spec'd by Standard, no device specific
minimum
        R/W multiple sector transfer: Max = 16  Current = 16
        Advanced power management level: unknown setting (0x0000)
        Recommended acoustic management value: 192, current value: 254
        DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5
*udma6
             Cycle time: min=120ns recommended=120ns
        PIO: pio0 pio1 pio2 pio3 pio4
             Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
        Enabled Supported:
           *    NOP cmd
           *    READ BUFFER cmd
           *    WRITE BUFFER cmd
           *    Host Protected Area feature set
           *    Look-ahead
           *    Write cache
           *    Power Management feature set
                Security Mode feature set
           *    SMART feature set
           *    FLUSH CACHE EXT command
           *    Mandatory FLUSH CACHE command
           *    Device Configuration Overlay feature set
           *    Automatic Acoustic Management feature set
                SET MAX security extension
                Advanced Power Management feature set
           *    DOWNLOAD MICROCODE cmd
           *    SMART self-test
           *    SMART error logging
Security:
        Master password revision code = 65534
                supported
        not     enabled
        not     locked
                frozen
        not     expired: security count
        not     supported: enhanced erase
HW reset results:
        CBLID- above Vih
        Device num = 0 determined by the jumper
Checksum: correct