SBP2 queries

Frank Banul f-banul at ti.com
Wed Apr 21 08:13:10 PDT 1999


* From the T10 Reflector (t10 at symbios.com), posted by:
* "Frank Banul" <f-banul at ti.com>
*
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Hi Nitin,

answers below...

Frank Banul
f-banul at ti.com

Texas Instruments Storage Products Group
8360 LBJ Freeway, M/S 8214
Dallas, TX 75243


  -----Original Message-----
  From: owner-t10 at Symbios.COM [mailto:owner-t10 at Symbios.COM]On Behalf Of
Nitin Samar
  Sent: Wednesday, April 21, 1999 6:36 AM
  To: T10 at Symbios.COM
  Subject: Fw: SBP2 queries




  SBP2 Query

  Let's say an application on top of SBP2 wants to transfer a file from
target to initiator. So in this case depending on the size of the file the
target will send  multiple write request to initiator. I wanted to know that
how does the target side application interact with the SBP2. On the
initiator side the SBP2 will make a command ORB ( assuming that it has
alreadyt logged into target) and signal to target. Now target reads the ORB
and finds it is for data write to initiator. Now on the target side SBP2 has
to take data from application and then it has to send to initiator. Do the
target has to make some kind of ORB and then send the request to initiator
or the async block/quadlet write could directly be done.

  Once the target receives and decodes the ORB, it either has the address to
write to (by the data_descriptor) or it fetches the page table (pointed to
by the data_descriptor). Then it performs the necessary async writes to the
initiator. The data transfer is not in SBP-2 defined entities.

  SBP2 says that a node can act as target and initiator simultaneously. I
wanted to know whether for a single transaction(say initiator wants to read
qaudlet data from target) the switching to target/initaitor is necessary.
  Or the switching is done when same node is interacting with two different
node and acting as initiator for one and target to other.

  If a node is a target and an initiator, then it has both the capability to
dispatch and interpret ORBs. If I understand your question correctly, a node
would never be the initiator to it's own target, it would be target to one
or more other initiator nodes and an initiator to one or more other target
nodes.

  Regards,

  Nitin


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 Hi=20 Nitin,
  
 answers below...
  
 Frank Banul
f-banul at ti.com

Texas Instruments = Storage=20 Products Group
8360 LBJ Freeway, M/S 8214
Dallas, TX 75243 =  
 -----Original Message-----
From: = owner-t10 at Symbios.COM=20 [mailto:owner-t10 at Symbios.COM]On Behalf Of Nitin = Samar
Sent:=20 Wednesday, April 21, 1999 6:36 AM
To:=20 T10 at Symbios.COM
Subject: Fw: SBP2 = queries


  
  
 SBP2 Query
  
 Let's say an = application on=20 top of SBP2 wants to transfer a file from target to initiator. So in = this case=20 depending on the size of the file the target will send  multiple = write=20 request to initiator. I wanted to know that how does the target side=20 application interact with the SBP2. On the initiator side the SBP2 = will make a=20 command ORB ( assuming that it has alreadyt logged into target) and = signal to=20 target. Now target reads the ORB and finds it is for data write to = initiator.=20 Now on the target side SBP2 has to take data from application and then = it has=20 to send to initiator. Do the target has to make some kind of ORB and = then send=20 the request to initiator or the async block/quadlet write could = directly be=20 done. 
  
 Once the target receives and decodes the = ORB, it=20 either has the address to write to (by the data_descriptor) or it = fetches the=20 page table (pointed to by the data_descriptor). Then it performs the = necessary=20 async writes to the initiator. The data transfer is not in SBP-2 = defined=20 entities.
  
 SBP2 says that a node can act as target and = initiator=20 simultaneously. I wanted to know whether for a single transaction(say=20 initiator wants to read qaudlet data from target) the switching to=20 target/initaitor is necessary. 
 Or the switching is done when same node is = interacting with=20 two different node and acting as initiator for one and target to=20 other.
  
 If a=20 node is a target and an initiator, then it has both the capability to = dispatch=20 and interpret ORBs. If I understand your question correctly, a = node would=20 never be the initiator to it's own target, it would be target to one = or more=20 other initiator nodes and an initiator to one or more other target=20 nodes.
  
 Regards,
  
 Nitin
  


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