Building an iSCSI storage device can be very helpful for proof of concepts or actually for production use. I prefer using a Linux Server that provides an iSCSI storage for proof of concept scenarios because real SANs cost a lot of money. iSCSI is the abreviation of Internet Small Computer System Interface and it is an Internet Protocoll (IP). iSCSI is a standard for linking storage facilities.
The iSCSI Enterprise Target is an Open Source project to implement professional iSCSI feature for Linux and provides the iscsitarget software. Ubuntu included iscsitarget package in there repositories and cam be installed with apt-get.
In my demonstration I will make use of a image file which will be the storage device. Storage device is probably not the correct term but best describes its purpose. Usually you will use a logical volume, hard drive or a partition as a block device but it works with image files as well.
Every iSCSI Target defined with an IQN. I copied the definition from Wikipedia.
- iSCSI Qualified Name (IQN)
- Format: The iSCSI Qualified Name is documented in RFC 3720, with further examples of names in RFC 3721. Briefly, the fields are:
- literal iqn
- date (yyyy-mm) that the naming authority took ownership of the domain
- reversed domain name of the authority (org.alpinelinux, com.example, to.yp.cr)
- Optional “:” prefixing a storage target name specified by the naming authority.
- From the RFC:
Naming String defined by Type Date Auth "example.com" naming authority +----+ +-----+ +---------+ +-----------------------------+ iqn.2001-04.com.example:storage:diskarrays-sn-a8675309 iqn.2001-04.com.example iqn.2001-04.com.example:storage.tape1.sys1.xyz iqn.2001-04.com.example:storage.disk2.sys1.xyz
To enhance the security iSCSI make use of CHAP protocol for authentication and the credentials are not sent in clear text over the wire. In all the iSCSI storage implementation I worked on the iSCSI is been placed in its own VLAN and only accessible for the Servers that utilizes iSCSI SAN Storage like VMware ESX or Citrix Xen server Hosts.
Enjoy the following Youtube Video which demonstrates a simple iSCSI Storage on a Ubuntu Linux Server.