Free Webinar
August 1 | 11am PT / 2pm ET
Looking for something beyond your traditional VMs?
Try application containers!
Speaker: Ivan Talaichuk, Solutions Engineer, StarWind

Creating a stand-alone LSFS device with StarWind Virtual SAN

Published: January 23, 2018


StarWind Virtual SAN® is a native Windows hypervisor-centric hardware-less VM storage solution. It creates a fully fault tolerant and high performing storage pool purpose-built for the virtualization workloads by mirroring the existing server’s storage and RAM between the participating storage cluster nodes. StarWind Virtual SAN delivers supreme performance compared to any dedicated SAN solution since it runs locally on the hypervisor. All IO is processed by local RAM, SSD cache, and disks and never gets bottlenecked by storage fabric.

This guide is intended for experienced StarWind users and Windows system administrators and IT professionals who would like to configure StarWind Virtual SAN solution. It provides detailed instructions on how to create a shared storage configuration using StarWind Virtual SAN that runs on top of Windows Server 2012 R2 and Windows Server 2016.

A full set of up-to-date technical documentation can always be found here, or by pressing the Help button in the StarWind Management Console.

For any technical inquiries, please, visit our online community, Frequently Asked Questions page, or use the support forum to contact our technical support department.

Technical description and requirements

LSFS is a snapshot-based file system that uses snapshots according to the concept of journaling file system. LSFS device uses a log-structured file system (journal file system) that keeps the changes made in the journal. This file system keeps no data, only changes. Every snapshot is incremental and occupies additional space equal to changes made since the previous snapshot creation. Junk rate predetermines the maximum-allowed LSFS growth (overprovisioning) comparison to the declared LSFS size. The default rate (60%) causes LSFS file-segments to use 2.5 times more space than the initial LSFS size. Additionally, metadata occupies up to 20% of the initial LSFS size resulting in a total 200% LSFS devices overprovisioning.

LSFS requirements:

  1. 4.6 GB of RAM per 1 TB of LSFS size without deduplication. For example, if you have a 10 TB LSFS device, it requires 46 GB of free RAM.
  2. 7.6 GB of RAM per 1 TB of LSFS size with deduplication. For example, if you have a 10 TB LSFS device, it requires 76 GB of free RAM.
  3. Over-provisioning is 200% (LSFS files can occupy 3 times more space compared to initial LSFS size).
  4. Snapshots require additional space to store them.

Creating an LSFS device

1.  Launch StarWind Management Console: double-click the StarWind tray icon.

NOTE: StarWind Management Console cannot be installed on an operating system without a GUI. You can install it on any GUI-enabled Windows Editions including the desktop versions of Windows.


If StarWind Service and Management Console are installed on the same server, the Management Console will automatically add the local StarWind instance to the Console tree after the first launch. Then, the Management Console connects to it automatically using the default credentials. To add remote StarWind servers to the console use the Add Server button on the control panel.

2. StarWind Management Console will ask you to specify the default storage pool on the server you’re connecting to for the first time. Please, configure the storage pool to use one of the volumes you’ve prepared earlier. All the devices created through the Add Device wizard will be stored on it. Should you decide to use an alternative storage path for your StarWind virtual disks, please use the Add Device (advanced) menu item.


Press Yes button to configure the storage pool. If you require changing the storage pool destination, press Choose path… and point the browser to the necessary disk.

NOTE: Each array used by StarWind Virtual SAN to store virtual disk images should meet the following requirements:

  • initialized as GPT
  • Have a single NTFS-formatted partition
  • Have a drive letter assigned

3. Click the Add Device (advanced) button on the toolbar.


4. Add Device Wizard will appear. Select Hard disk device and click Next.


5. Select Virtual disk and click Next.


6. Specify the virtual disk Name, location, size and click the Next button.


7. Choose the LSFS option instead of the Thick-provisioned one. If you need enable the LSFS device deduplication, check the “Deduplication” box. Click the Next button to proceed.

NOTE: StarPack Cache is the low-level cache located between the disk and the LSFS log. It caches log fragments, which are later prepared for writing to the disk or read from it. If deduplication is enabled on the device, the data in the StarPack cache is also deduplicated. The recommended size is 16 MB.

NOTE: 4096 Virtual Block size is recommended for Windows-based hypervisors; 512 for Linuxbased ones (ESXi/Xen/KVM)


8. Define the caching policy, specify the cache size (in MB) and click Next.

NOTE: It is not recommended to configure cache in Write-Back mode on Standalone devices in order to avoid possible data corruption upon power outage or incorrect service shutdown. It is recommended to put 1 GB of L1 cache per 1 TB storage capacity.


9. Define the Flash Cache Parameters policy and size if necessary. Choose SSD location in the wizard.

NOTE: The recommended L2 cache size is 10% of initial StarWind device capacity.


10. Select the Target Name checkbox to enter a custom target name. Otherwise, the name will be generated automatically based on the target alias. Click Next to continue.


11. Click Create to add a new device and assign it to the target.


12. Click Close to complete the wizard.


13. The added device will appear in the StarWind Management Console.


Discovering and Connecting Target Portals

14. Launch Microsoft iSCSI Initiator: Start > Administrative Tools > iSCSI Initiator or iscsicpl from the command line interface. The iSCSI Initiator Properties window appears.

15. Navigate to the Discovery tab.

16. Click the Discovery button. Discover Target Portal dialog appears. Type in if you are going to connect the virtual drive from the local host.


17. Click the Advanced button. Select Microsoft iSCSI Initiator as your Local adapter and select your Initiator IP (leave default for


18. Click OK twice to complete the Target Portal discovery.

19. Click on the Targets tab.

NOTE: If the created targets are not listed, check the StarWind Server firewall and the list of networks served by the StarWind Server (go to StarWind Management Console -> Configuration -> Network).

20. Select a target of the stand-alone device located on the local server and click Connect.


21. Add the target to the Favorites list and enable multi-path. Click Advanced.


22. Select in the Target portal IP and Microsoft iSCSI Initiator as the default initiator.


Click OK and finish the connection.

23. Make sure that your device status is Connected as shown in the picture below:


24. Initialize the disks and create partitions on them using the Disk Management snap-in. The disk devices are required to be visible on both nodes in order to create the cluster.

NOTE: it is recommended to initialize the disks as GPT.


LSFS is a snapshot-based file system that saves only changes made in the environment. Here, we discussed setting up the stand-alone LSFS device using StarWind Virtual SAN for creating a shared storage configuration.