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Date:      Tue, 6 Oct 1998 22:07:23 +0100
From:      Paul Haigh <paul@nailed.demon.co.uk>
To:        "aic7xxx@freebsd.org" <aic7xxx@FreeBSD.ORG>
Subject:   Synchronous/Asynchronous and Disconnect/Connect?
Message-ID:  <01BDF175.B29F64A0.paul@nailed.demon.co.uk>

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All,

Sorry If I'm asking a silly question but here goes anyway:

I'm a little confused about the difference between Sync and Async (and also 
disconnect and connect).  I've read a lot of stuff about the changing of 
harddisc jumper settings to alter the behaviour of the driver under Linux. 
 (To either enable it or disable it)

Am I missing a simple trick to speed up my discs?

I've got two older Sun Microsystems discs in my linux server (both 4.5Mb 
SCA drives)

The driver purports the following:

------------------------------------------------------------------------

Adaptec AIC7xxx driver version: 5.1.0pre6/3.2.4
Compile Options:
  AIC7XXX_RESET_DELAY    : 15
  AIC7XXX_TAGGED_QUEUEING: Adapter Support Enabled
                             Check below to see which
                             devices use tagged queueing
  AIC7XXX_PAGE_ENABLE    : Enabled (This is no longer an option)
  AIC7XXX_PROC_STATS     : Enabled

Adapter Configuration:
           SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
                           Ultra Wide Controller
    PCI MMAPed I/O Base: 0xe1000000
      Adaptec SCSI BIOS: Enabled
                    IRQ: 11
                   SCBs: Active 0, Max Active 2,
                         Allocated 15, HW 16, Page 255
             Interrupts: 47205
      BIOS Control Word: 0x19b6
   Adapter Control Word: 0x005f
   Extended Translation: Enabled
Disconnect Enable Flags: 0xffff
     Ultra Enable Flags: 0xfffa
 Tag Queue Enable Flags: 0x0000
Ordered Queue Tag Flags: 0x0000
Default Tag Queue Depth: 8
    Tagged Queue By Device array for aic7xxx host instance 0:
      {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
    Actual queue depth per device for aic7xxx host instance 0:
      {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}

Statistics:
(scsi0:0:0:0)
  Device using Wide/Sync transfers at
  20.0 MByte/sec, offset 8
    Total transfers 36744 (21442 read;15302 written)
      blks(512) rd=71931; blks(512) wr=42780
        < 512 512-1K   1-2K   2-4K   4-8K  8-16K 16-32K 32-64K 64-128K 
>128K
 Reads:     0      1  18818    434   1170    945     26     27     21 
     0
Writes:     0      0  13117   1857    266     34      4      3     21 
     0

(scsi0:0:2:0)
  Device using Wide/Sync transfers at
  20.0 MByte/sec, offset 8
    Total transfers 10402 (5637 read;4765 written)
      blks(512) rd=81923; blks(512) wr=55246
        < 512 512-1K   1-2K   2-4K   4-8K  8-16K 16-32K 32-64K 64-128K 
>128K
 Reads:     0      1   2581     75   1051   1474    166    107    182 
     0
Writes:     0      0   3372    760    426     23     15      3    166 
     0

------------------------------------------------------------------------

I only get around 5Mb/sec on these drives, which I would say was less than 
I was expecting.  Is the sync/async thing slowing me down?

This is running on an Adaptec 2940 UW controller.

Thanks for any help in advance.

Cheers,

Paul Haigh.

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