[ale] Disk performance

[Alex Carver]

I started revisiting some of the performance issues with one of my 
systems (slow startup of any program) and removing anything that may 
have interfered (HAL, fuse, etc., removing atime) so now I'm down to 
basic disk access.  Using iotop, it seems the disk is running slower 
than I recall (transfer rates of about 200 K/s).

I'd appreciate any suggestions on areas to look short of a wipe and 
reload (I don't currently have spare drives) but any other performance 
checks and tweaks would be good.  It had been working fine for a long 
time and only recently has had any issues.

I do have hdparm installed and there are two disks in the system both on 
the primary IDE channel.

The report from hdparm:

/dev/sda:

  Model=Maxtor 90840D6, FwRev=WAS8283C, SerialNo=K60A721A
  Config={ Fixed }
  RawCHS=16276/16/63, TrkSize=0, SectSize=0, ECCbytes=29
  BuffType=DualPortCache, BuffSize=256kB, MaxMultSect=16, MultSect=16
  CurCHS=16276/16/63, CurSects=16406208, LBA=yes, LBAsects=16406208
  IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
  PIO modes:  pio0 pio1 pio2 pio3 pio4
  DMA modes:  mdma0 mdma1 mdma2
  UDMA modes: udma0 udma1 *udma2
  AdvancedPM=no WriteCache=enabled
  Drive conforms to: ATA/ATAPI-4 T13 1153D revision 17:  ATA/ATAPI-1,2,3,4

ATA device, with non-removable media
         Model Number:       Maxtor 90840D6
         Serial Number:      K60A721A
         Firmware Revision:  WAS8283C
Standards:
         Used: ATA/ATAPI-4 T13 1153D revision 17
         Supported: 4 3 2
Configuration:
         Logical         max     current
         cylinders       16276   16276
         heads           16      16
         sectors/track   63      63
         --
         CHS current addressable sectors:   16406208
         LBA    user addressable sectors:   16406208
         Logical/Physical Sector size:           512 bytes
         device size with M = 1024*1024:        8010 MBytes
         device size with M = 1000*1000:        8399 MBytes (8 GB)
         cache/buffer size  = 256 KBytes (type=DualPortCache)
Capabilities:
         LBA, IORDY(can be disabled)
         bytes avail on r/w long: 29
         Standby timer values: spec'd by Standard
         R/W multiple sector transfer: Max = 16  Current = 16
         DMA: mdma0 mdma1 mdma2 udma0 udma1 *udma2
              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:
            *    SMART feature set
            *    Power Management feature set
            *    Write cache
            *    Look-ahead
            *    Host Protected Area feature set
            *    WRITE_VERIFY command
            *    WRITE_BUFFER command
            *    READ_BUFFER command
            *    NOP cmd
            *    DOWNLOAD_MICROCODE


  * signifies the current active mode

  multcount     = 16 (on)
  IO_support    =  0 (default)
  readonly      =  0 (off)
  readahead     = 256 (on)
  geometry      = 1021/255/63, sectors = 16406208, start = 0