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How to use VJBOD (Virtual JBOD) to share the storage capacity of multiple QNAP NAS

1. Introduction

Virtual JBOD allows you to allocate the free space of QNAP NAS to another NAS in order to maximize the total available storage capacity.

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How Virtual JBOD works: Use the free space of a NAS to create an iSCSI LUN and add this LUN to a local NAS as a hard drive.

By using VJBOD you are not restricted to physical limitations for expanding NAS storage and expansion enclosures are not required. With flexible network transmission, you can establish 1/10/40GbE network storage along with backup connections, so that every NAS can be used with maximum efficiency, and entry-level NAS can be used to compliment higher-end models.

 
VJBOD
JBOD
Connection
Ethernet (1/10/40GbE) USB 3.0 or SAS 6/12Gb
Number
8 Virtual JBOD Disks Depends on NAS Model
Chain
N/A Daisy chain for SAS JBOD
Backup Connection
Port Trunking No
Usage scenarios
When multiple NAS with excess space are available. VJBOD does not currently support direct expansion of local storage pool. When direct rapid expansion of local storage is required.

*Virtual JBOD Disk does not support expanding local Storage Pool.

2. System Requirements

2.1. Hardware

VJBOD currently supports the models at: https://www.qnap.com/solution/vjbod, and requires firmware 4.2.2 (or newer). Any QNAP NAS that supports iSCSI and storage pools can be used as a remote NAS, but it is recommended that they use firmware 4.2 (or newer) and have at least 154GB free space.

For more information and future support models, please refer to the QNAP website and software spec of each product for detail.

2.2. Network Requirements

Both NAS must be able to identify and connect to each other. For greater connection stability and to automatically recover from connection failure, it is recommended that both remote and local NAS be on the same local network and that the remote NAS uses a static IP address.

If the remote NAS does not require all of its Ethernet ports, it is also recommended to enable Port Trunking for the remote NAS. This will secure the connection and prevent possible data loss in the event that a port fails.

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You can find the Port Trunking option in the Network settings. Change the first connection to a static IP address.
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Check both connections to allow them to use the same IP address to increase performance and to provide failover*.

*For connecting through a normal switch, you can choose Balance-rr (Round-Robin) or Active Backup accordingly. For switches that support Link Aggregation, you can also use 802.3ad to improve overall performance.

*Please note that Port-Trunking cannot be used with direct connection currently due to Network & Virtual Switch’s limitation.

2.3. SSD Cache

As the random read and write performance of the Virtual JBOD's Storage Pool may decrease from 20% to 30% compared to the host NAS's Storage Pool due to the data transmission process between devices, we recommend using a Virtual JBOD primarily for file sharing with sequential read and write access as its general usage pattern. For other application, we recommend using an SSD cache on the Host NAS to increase the Virtual JBOD's Storage Pool performance.

For more information regarding SSD caching, please refer to https://www.qnap.com/solution/ssd-cache/en-in/index.php

QNAP
Using SSD cache to enhance Virtual JBOD's performance.

3. Using VJBOD

3.1. Using VJBOD's Disk Create Wizard

In this example we use a TVS-882 and TS-87. Using the TVS-882, go to "Storage Manager" > "Disks" and click "Virtual JBOD", "Create Virtual JBOD" in the top-left corner. In the second step of the wizard, you can directly enter the IP address of the remote NAS or automatically detect it. There is also an option called "Local Host" that allows you to mount an existing iSCSI LUN on the host to retrieve its data if it once serviced as a Virtual JBOD disk.

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In this example we demonstrate how the free space of a TS-879 can be used by a TVS-882.
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Finding the remote NAS.

You will then be able to choose the remote NAS storage pool to create a new Virtual JBOD Disk (block-level iSCSI LUN) or choose an existing iSCSI LUN and use it as a disk. Thin-provisioned iSCSI LUNs cannot be used. When creating a new Virtual JBOD disk, click "NAS Detail" in the top-right corner to check the storage status of the NAS. Host Binding can ensure data security by only allowing the TVS-882 to access the Virtual JBOD Disk, or you can use iSCSI with CHAP protection in the next step. Both options can help protect disk data*.

*If the firmware of the remote NAS is 4.2.2 (or newer), changing the remote NAS's admin password automatically disconnects the Virtual JBOD's connection until the new password is entered.

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Create a new Virtual JBOD disk or use an existing iSCSI LUN as a disk.
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Select the space to use in the new virtual disk.

If you are creating a new disk you will be asked how much space to use. Once you complete this wizard you will receive instructions on how to use the VJBOD's disk with some suggested actions. Creating a new Storage Pool or Volume will take you to the Storage Pool or Volume Creation Wizard, while Recover Existing Data will scan connected Virtual JBOD Disks to retrieve its data. You can also access these instructions from QTS Help when needed.

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Set the size of the disk.
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Instructions on using VJBOD will be displayed.

If you choice Do Nothing, you can now use the new Virtual JBOD Disk in the tab "Storage Space" by selecting "Create" > "New Storage Pool" or "New Volume". How the disk is used is no different from an actual disk, with the following limits:
VJBOD currently only supports "Single" RAID configuration and cannot be used to create a system volume or expand other storage pools unless the Pool also consists of Virtual JBOD Disks that come from the same remote NAS and same Pool. The expansion of size of the LUN on the remote NAS will not be reflected on the Virtual JBOD disk.

Therefore, to expand a Virtual JBOD Pool, You can only do so by creating a new Virtual JBOD Disk on the same Storage Pool and joining the disk into the pool as a new RAID.

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When the connection is complete, you can check the status of the new Virtual JBOD Disk details in "Disk".
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Using a Virtual JBOD Disk to create a Storage Pool.
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The Virtual JBOD Disk's Storage Pool can be used as the local disk's pool with functions such as snapshots enabled.

4. Manage VJBOD

4.1. Monitoring VJBOD

There are some features that allow you to monitor the Virtual JBOD connection status or the condition of the Remote NAS without any additional tools. First, in "Disks" you can select a Virtual JBOD Disk and click "Action" to check the details of the remote NAS or the Storage Pool Log where the Virtual JBOD Disk is located. This will allow you to identify issues with the remote Pool if the Virtual JBOD Disk becomes abnormal.

Clicking the Virtual JBOD Overview icon in the top right of Storage Manager will allow you to see every Virtual JBOD's connection and the general condition and disk configurations of every remote NAS.

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Using the “Remote Log” function to see the Remote Storage Pool Log of the selected Virtual JBOD Disk.
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The Virtual JBOD Overview page will give you a summary on all the Virtual JBOD Connections.

If the firmware of the remote NAS is 4.2.2 (or newer) you can use the Storage Manager's new iSCSI Storage UI to monitor what NAS has connected to an iSCSI LUN, as well as receiving warnings if the iSCSI connection is lost. If more detailed monitoring is required for multiple NAS, you can use Q'center to monitor both Host and Remote NAS.

For more details regarding Q'center, please refer to: http://www.qnap.com/solution/qcenter/index.php?lang=en-in

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Starting from 4.2.2, the NAS iSCSI Storage page can show more information regarding the connected iSCSI initiator.
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Q'center can be used when need to monitor more than one NAS at the same time.

4.2. Disconnect/Transfer VJBOD

Every Virtual JBOD Disk will be listed under "Disks" in Storage Manager, and different actions will be available when the Virtual JBOD Disk is under different conditions. For a newly-created and free Virtual JBOD Disk, you can click “New Volume”, edit the disk name, or disconnect the Virtual JBOD Disk. If the disk has been used to create a Virtual Volume or Storage Pool, you will be unable to directly disconnect the Disk unless it is in abnormal condition or you select "Safely Detach" in the “Storage Space” Tab. Once you disconnect a Virtual JBOD Disk, it will not immediately disappear from the "Disk". It will instead enter the "Disconnected" status. Only disconnected Virtual JBOD Disks can be removed from the list, or you can choose to reconnect it.

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The disconnected Virtual JBOD Disk will be marked as Disconnected in the Disk tab.

As previously mentioned, Virtual JBOD Disks can be used to conduct data roaming to transfer data from one NAS to another one without needing to physically disconnect and reconnect drives. To do so, first "Safely Detach" a Virtual JBOD Disk then go to the NAS that you want to move the data to, open the Virtual JBOD Wizard and choose the existing iSCSI LUN on the remote NAS to mount the data within the Virtual JBOD Disk.

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Use "Safety Detach Pool" to disconnect a Virtual JBOD Disk and start the process of moving the storage pool to another NAS.
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Re-establishing a Virtual JBOD Disk connection by selecting "Choose an existing iSCSI LUN on the remote NAS".
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Select a previously-used Virtual JBOD Disk.
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When the virtual disk is reconnected to a NAS, select "Recover" > "Scan All Free Disks" to retrieve the disk's data.
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When the scan is completed, the virtual disk's storage pool, volume, snapshots, and relevant information will be available to this NAS.

4.3. Error Handling

The Virtual JBOD iSCSI connection features an automatic reconnection mechanism. If the system cannot access a Virtual JBOD Disk's Storage Pool within 30 seconds, the storage pool error protection mechanisms will prevent additional operations from being made as the Virtual JBOD Disk becoming disconnected. At this time, the system will automatically try to reconnect the disk. Please note that this automatic reconnection mechanism will only function if the remote NAS has a static IP address. If the IP address of the remote NAS changes, you must selected the disconnected Virtual JBOD Disk, click “Action” and select "Edit the Target" to enter the new IP address.

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If the remote NAS is inaccessible, the storage pool error protection mechanisms will be activated to avoid additional I/O errors. If the remote NAS uses a static IP address, the system will automatically reconnect to the virtual disk once the network has been restored.
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Select "Edit Target" to input the new IP address for the Virtual JBOD Disk to reconnect manually.

Storage space can still be used if the Web management port numbers on the remote NAS changes, but some NAS information may not be correct. If this occurs, in "Disk" > Select the disk and "Action"> "Re-login" to enter new information. You can also input the new admin password if the Remote NAS password is changed when the Virtual JBOD Disk is disconnected.

QNAP
Update authentication information or port numbers in Re-login.
Release date: 2016-06-23
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