Veritas-bu

Re; [Veritas-bu] 4.5 MP4 -Best method for migrate Master from Solaris to Windows 2k

2004-03-01 06:45:56
Subject: Re; [Veritas-bu] 4.5 MP4 -Best method for migrate Master from Solaris to Windows 2k
From: william.d.brown AT gsk DOT com (william.d.brown AT gsk DOT com)
Date: Mon, 1 Mar 2004 11:45:56 +0000
You may have no problem with buffers >64k on Windows.  It depends on the 
SCSI drivers your hardware actually uses; we have some fibre channel 
drivers that are fine up to large sizes.   If it uses the Windows miniport 
driver, then you do need to make registry changes.   Search on the 
internet for "MaximumSGlist".  Here is an article that tells a good deal:

http://www.eetkorea.com/ARTICLES/2000APR/2000APR05_CT_ID_AN.PDF

You will have to find the registry key for your particular adapter.  Here 
is a bit for a Qlogic adapter:

6.1. System Registry Parameters
--------------------------------

*  MaximumSGList

   Windows includes enhanced scatter/gather list support for 
   doing very large SCSI I/O transfers. Windows supports up to 
   256 scatter/gather segments of 4096 bytes each, allowing transfers
   up to 1048576 bytes.

   NOTE: the OEMSETUP.INF file has been updated to automatically 
         update the registry to support 65 scatter/gather segments.
         Normally, no additional changes will be necessary as this 
         typically results in the best overall performance.

   If you wish to alter this value, please use the following 
   procedure:

   1. Click on "Start", select "Run", and open the REGEDT32 program.
   2. Select HKEY_LOCAL_MACHINE and follow the tree structure down to
      the QLogic driver as follows:

          HKEY_LOCAL_MACHINE
             SYSTEM
                CurrentControlSet
                   Services
                      Ql2300
                         Parameters
                            Device

   3. Double click on

          MaximumSGList:REG_DWORD:0x21

   4. Enter a value from 16 to 255 (0x10 hex to 0xFF).  A value of 
      255 (0xFF) enables the maximum 1 MByte transfer size.  Setting 
      a value higher than 255 results with the default of 64K 
      transfers.  The default value is 33 (0x21).

   5. Click OK.

   6. Exit the Registry Editor, then shutdown and reboot the system.


=====================

And another piece of the same info:

The formula to calculate the proper value for MaximumSGList is:

     MaximumSGList = ((Maximum Block Size)/4 Kbytes) +1

For 256 Kbytes: 256 Kbytes/4 Kbytes = 64. Add 1 for 65 (decimal) or 
0x41 (hexadecimal). The maximum value allowed for MaximumSGLIst is 255 or 
0xFF. For the particular value of 0xFF, the internal value passed to 
Windows 
is increased to 0x101, allowing support for a full 1 Mbyte transfer.

The system must be rebooted for the new registry setting to be effective.

NOTE: For 64-bit systems, the OS page size is 8 Kbytes instead of 4 
Kbytes. 
      Therefore, the maximum transfer size is 2 Mbytes, the default driver 

      installation enables support for 512 Kbytes transfer size, and the 
      formula becomes:
 
          MaximumSGList = ((Maximum Block Size)/8 Kbytes) +1


William D L Brown


> You have a challenge here...I believe from a theoretical perspective
> this should work okay.  However, if your solaris master was tuned 
> with large buffers (>64K) then your new Windows 2K Master/Media 
> server will not be able to read the data for restore.  Unless you 
> make some registry hacks (which I can't find now) on your W2K box.



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