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https://github.com/shmuma/scst_local

SCST local target with refresh functionality
https://github.com/shmuma/scst_local

Last synced: 25 days ago
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SCST local target with refresh functionality

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README 

        
SCST Debug ...

Richard Sharpe, 30-Nov-2008



This is the SCST Local driver. Its function is to allow you to access devices

that are exported via SCST directly on the same Linux system that they are

exported from.



No assumptions are made in the code about the device types on the target, so

any device handlers that you load in SCST should be visible, including tapes

and so forth.



You can freely use any sg, sd, st, etc. devices imported from target,

except the following: you can't mount file systems or put swap on them.

This is a limitation of Linux memory/cache manager. See SCST README file

for details.



To build, simply issue 'make' in the scst-local directory.



Try 'modinfo scst_local' for a listing of module parameters so far.



NOTE! This is now part of scst and supports being built in the scst tree.



Here is how I have used it so far:



1. Load up scst:



  modprobe scst

  modprobe scst_vdisk



2. Create a virtual disk (or your own device handler):



  dd if=/dev/zero of=/some/path/vdisk1.img bs=16384 count=1000000

#  dd if=/dev/zero of=/some/path/vdisk2.img bs=16384 count=1000000

  echo "open vm_disk1 /some/path/vdisk1.img" > /proc/scsi_tgt/vdisk/vdisk

#  echo "open vm_disk2 /some/path/vdisk2.img" > /proc/scsi_tgt/vdisk/vdisk

  echo "add vm_disk1 0" > /proc/scsi_tgt/groups/Default/devices

#  echo "add vm_disk2 1" > /proc/scsi_tgt/groups/Default/devices



3. Load the scst_local driver:



  insmod scst_local

# insmod scst_local max_luns=8



4. Check what you have



   cat /proc/scsi/scsi

  Attached devices:

  Host: scsi0 Channel: 00 Id: 00 Lun: 00

    Vendor: ATA      Model: ST9320320AS      Rev: 0303

    Type:   Direct-Access                    ANSI  SCSI revision: 05

  Host: scsi4 Channel: 00 Id: 00 Lun: 00

    Vendor: TSSTcorp Model: CD/DVDW TS-L632D Rev: TO04

    Type:   CD-ROM                           ANSI  SCSI revision: 05

  Host: scsi7 Channel: 00 Id: 00 Lun: 00

    Vendor: SCST_FIO Model: vm_disk1         Rev:  101

    Type:   Direct-Access                    ANSI  SCSI revision: 04



5. Have fun.



Some of this was coded while in Santa Clara, some in Bangalore, and some in

Hyderabad. Noe doubt some will be coded on the way back to Santa Clara.



The code still has bugs, so if you encounter any, email me the fixes at:



   [email protected]



I am thinking of renaming this to something more interesting.



6. Change log



V0.1 24-Sep-2008 (Hyderabad) Initial coding, pretty chatty and messy,

                             but worked.



V0.2 25-Sep-2008 (Hong Kong) Cleaned up the code a lot, reduced the log

			     chatter, fixed a bug where multiple LUNs did not

			     work. Also, added logging control. Tested with

			     five virtual disks. They all came up as /dev/sdb

			     through /dev/sdf and I could dd to them. Also

			     fixed a bug preventing multiple adapters.



V0.3 26-Sep-2008 (Santa Clara) Added back a copyright plus cleaned up some

			       unused functions and structures.



V0.4 5-Oct-2008 (Santa Clara) Changed name to scst_local as suggested, cleaned

			      up some unused variables (made them used) and

			      change allocation to a kmem_cache pool.



V0.5 5-Oct-2008 (Santa Clara) Added mgmt commands to handle dev reset and

			      aborts. Not sure if aborts works. Also corrected

			      the version info and renamed readme to README.



V0.6 7-Oct-2008 (Santa Clara) Removed some redundant code and made some

			      changes suggested by Vladislav.



V0.7 11-Oct-2008 (Santa Clara) Moved into the scst tree. Cleaned up some

			       unused functions, used TRACE macros etc.



V0.9 30-Nov-2008 (Mtn View) Cleaned up an additional problem with symbols not

			    being defined in older version of the kernel. Also

			    fixed some English and cleaned up this doc.