Let us learn iSCSI

[AmitKumarDas]

• WZero

  - volume configured with "WZero Enable" 
  - is an space/performance optimization parameter
  - results in performing some space cleanup activities 
    - whenever data is modified 
    - or deleted from the Volume, 
  - results in increased latency. 

• Automation & iovec struct

  - a small test program that creates an iovec struct (let's say in size of 4) 
    - and each iov_base starts from page beginning and 4k len:
      - 0 iov_base 0xe25000 iov_len 4096
      - 1 iov_base 0xe26000 iov_len 4096
      - 2 iov_base 0xe27000 iov_len 4096
      - 3 iov_base 0xe28000 iov_len 4096
    - readv/writev to send this iovec data
  - verify the no of BIO requests to the driver

• References

  - verify driver restriction based on transfer size
  - verify driver restriction based on atomicity of transfer
  - verify if driver expects a blocking @ userspace

• References

  - FreeBSD email - splitting iovecs to bios