DAC960 and cache...

[Nicolas Turro]

Hi, 

I have a Mylex Acceleraid 170 Raid board and i use 
 DAC960 RAID Driver Version 2.4.11 of 11 October 2001 
under linux (kernel 2.4.18).
Here is the cat /proc/rd/c0/current_status :

***** DAC960 RAID Driver Version 2.4.11 of 11 October 2001 *****
Copyright 1998-2001 by Leonard N. Zubkoff <[e-mail]>
Configuring Mylex AcceleRAID 170 PCI RAID Controller
  Firmware Version: 6.00-15, Channels: 1, Memory Size: 32MB
  PCI Bus: 0, Device: 6, Function: 0, I/O Address: Unassigned
  PCI Address: 0xFC000000 mapped at 0xE0800000, IRQ Channel: 16
  Controller Queue Depth: 512, Maximum Blocks per Command: 2048
  Driver Queue Depth: 511, Scatter/Gather Limit: 128 of 257 Segments
  Physical Devices:
    0:0  Vendor: QUANTUM   Model: ATLAS10K3_36_SCA  Revision: 020W
         Wide Synchronous at 160 MB/sec
         Serial Number: 344208142992
         Disk Status: Online, 71798784 blocks
    0:1  Vendor: QUANTUM   Model: ATLAS10K3_36_SCA  Revision: 020W
         Wide Synchronous at 160 MB/sec
         Serial Number: 344207749285
         Disk Status: Online, 71798784 blocks
    0:2  Vendor: QUANTUM   Model: ATLAS10K3_36_SCA  Revision: 020W
         Wide Synchronous at 160 MB/sec
         Serial Number: 344211046648
         Disk Status: Online, 71798784 blocks
    0:3  Vendor: QUANTUM   Model: ATLAS10K3_36_SCA  Revision: 020W
         Wide Synchronous at 160 MB/sec
         Serial Number: 344211046660
         Disk Status: Online, 71798784 blocks
    0:4  Vendor: QUANTUM   Model: ATLAS10K2-TY184J  Revision: DDD6
         Wide Synchronous at 160 MB/sec
         Serial Number: 161034310612
         Disk Status: Online, 35827712 blocks
    0:5  Vendor: QUANTUM   Model: ATLAS10K2-TY184J  Revision: DDD6
         Wide Synchronous at 160 MB/sec
         Serial Number: 161034412602
         Disk Status: Online, 35827712 blocks
    0:7  Vendor: MYLEX     Model: AcceleRAID 170    Revision: 0600
         Wide Synchronous at 160 MB/sec
         Serial Number:
  Logical Drives:
    /dev/rd/c0d0: RAID-6, Online, 107483136 blocks
                  Logical Device Initialized, BIOS Geometry: 255/63
                  Stripe Size: 64KB, Segment Size: 8KB
                  Read Cache Disabled, Write Cache Disabled
  No Rebuild or Consistency Check in Progress

as you see, both read and write cache are disabled. I don't manage to enable 
them... would you give me any clue ?

I also think my filesystem is slow : i used 
mke2fs -b 4096 -R stride=16 -i 16384 /dev/rd/c0d0p4
but i only get arround 5 Mo/s while doing a       tar c KDE | dd of=/dev/null
(KDE is a 715 Mo source/compilation tree of KDE)
Do you have any clue on how to improve this performance (direct sequencial
access on this disk using dd give me around 50 Mo/s)

Thx in advance for you help.

N. Turro