Tape drive is the only storage media of choice for an economically-valid archive strategy. In order to understand what is virtual tape library, we need to understand the original physical tape drives and tape libraries. Tape Library is a storage device containing one or more tape drives, slots to hold tape cartridges, and barcode reader to identify the tape cartridges. Tape drive is a data storage device which reads and writes data on a magnetic tape. Tape drive provides sequential access storage. Hard disk drive provides direct access storage. Magnetic tape data storage is used for archival data storage. Tape media has a favorable long archival stability. Virtual Tape Library have been around a long time. Tape once was slower backup option in mainframe data-centers, at that time hard disk cache based tape drive system arrived. That cache enabled faster writing of backup data. Virtual Tape Library is a system of storage and specialized virtualization software capable of emulating Tape Libraries.
What is Virtual Tape Library?
The first ever Tape Library was launched in 1992. Later Virtual Tape Library was IBM Virtual Tape Server (VTS) which was introduced in 1997 for the mainframe market. It used an ESCON like interface and functioned as a disk cache. Later similar system acquired by Sun Microsystems and Oracle. Later mainframe offerings came from EMC Corporation. Outside the mainframe environment, the interfacing solutions are SCSI, or more recently Fiber Channel or iSCSI. In current decade, Virtual Tape Library and Virtual Tape Drive offerings are from Seagate and HGST for popular “tape in cloud” solution. Because of various complex proprietary solutions of different generations, what is Virtual Tape Library not exactly easy to answer question.
At present, Virtual Tape Library runs on a Fiber Channel or TCP/IP storage network and sits next to the application server – with which it communicates – but before the tape storage libraries. The Virtual Tape Library aims to compensate for the disadvantages of tape storage with an intermediate layer disk system. One of the functions made possible by the implementation of Virtual Tape Library is deduplication. Most current Virtual Tape Library solutions use SAS or SATA disk arrays as the primary storage component. Array enclosures increases the scalability by allowing the addition of more disk drives. As example, AWS Storage Gateway provides Virtual Tape Backup to the Cloud which costs like object storage or CDN.
mhVTL is a free virtual tape library which is not production-ready. We can use it for non-production environments. There are proprietary virtual tape libraries. We can use any backup software with virtual tape libraries.
Enhanced performance, greater capacity, streamlined backup processes, reduced manual effort, data durability
and low-cost data archiving for long-term are the advantages of VTL.
How mhVTL Virtual Tape Library Works?
mhVTL is a free software, licensed under GNU GPL and this is their official website :
We can use two virtual box Centos machines or two virtual servers. The first will represents the VTL and the second will represent the backup machine. We need SELinux to be disabled. Then we will run the following commands:
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-6-6.el6.elrepo.noarch.rpm
yum install kmod-mhvtl mhvtl-utils
The above example is how we get started to use mhVTL Virtual Tape Library. We use a web UI to configure and there are many settings which needs to be configured.