SIRIS, ALTO, and NAS: What Is the difference between iSCSI Shares and NAS Shares?



What is the difference between iSCSI shares and NAS shares?


  • Datto ALTO
  • Datto SIRIS 
  • Datto NAS


NAS Shares

Network Attached Storage, also commonly known as a NAS share is file-level storage. It will appear as a drive on the network. From any machine on the network, the drive can be mapped and given a letter assignment such as (Z:).

A NAS share is shared storage, so multiple computers on the network can access it at the same time. The term NAS is also synonymous with the hardware appliance where the share lives.  

iSCSI Shares

An iSCSI share is block-level storage. This means it behaves like a physical drive directly attached to a computer. In this case, the share is referred to as an iSCSI target, which can be connected to via an iSCSI initiator.

Windows includes the ability to act as an iSCSI initiator, so an iSCSI share on a Datto NAS can show up like another local drive on any computer on the network. In contrast to a NAS share, an iSCSI target can only be accessed by one user (initiator) at a time, unless you have specialized software to do so.

Small Computer System Interface (SCSI): is a way to connect computers to peripherals like hard drives and tape drives. It has been around since 1981, and defines a set of commands for things like loading media, spinning up disks, and reading and writing data.

Internet Small Computer System Interface (iSCSI): lets a computer connect and communicate via SCSI with storage targets that live somewhere on a network instead of being directly attached to the computer.  

Figure 1: ISCSI and NAS shares

Shown above, an iSCSI target looks like a local drive, while a NAS share is shown as a network location, and made accessible via a mapped drive.

NAS shares and iSCSI shares have different restore options.

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