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NAS Storage Capacity Expander


ASUSTOR AS6004U 4-bay NAS Expander (Diskless)
(NAS Expander) 4x 2.5" / 3.5" SATAII / SATAIII or SSD, supports USB3.0, power sync mechanism | #AS6004U

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  • Plug and play online expansion
  • USB cable safety bracket a secure connection
  • Smart power sync helps to save power
  • Smart temperature control for stable operation
  • Supports MyArchive cold backup technology
  • Compatible with high capacity 16TB hard disks


Simply Plug it in

The AS6004U utilizes a USB 3.0 connection cable. Simply plug it into any ASUSTOR NAS to complete hardware expansion! Depending on the model*, ASUSTOR NAS devices can simultaneously connect up to 3 AS6004U units, satisfying the high capacity storage demands of enterprise users.

Simply Plug it in

*NAS series supporting expansion of up to 3 units: AS31/32/50/51/52/53/61/62/63/64/70 (other series are only able to expand up to 2 units)
*Please use the NAS's USB 3.0 port to connect the AS6004U
*Please use the ASUSTOR provided USB 3.0 cable
*If 70 series models have 12 devices plugged into USB 3.0 (1 hard disk = 1 device), the other USB ports will not be able to be used.
*On AS7012R devices, if 3 USB expansion units are plugged in (12 hard disks), then only one e-SATA port can be used.

Safety Bracket for Secure Connections

The security bracket and mounting hole design allow the AS6004U and USB cable to be connected securely without having to worry about disconnections.

Safety Bracket for Secure Connections

Secure Disk Tray Lock Design

In order to help users avoid accidentally pushing disk tray buttons and releasing hard disks during operation, ASUSTOR has added a new lock mechanism to its hard disk trays. The lock's flat-head design ensures that users will not need any special keys or tools to unlock it, only a simple flat-head screw driver. The new disks trays can be used with all ASUSTOR NAS devices, providing an additional layer of security for applications requiring the frequent swapping of hard disks (e.g., MyArchive).

Secure Disk Tray Lock Design

Smart Power Saving

The AS6004U has a power sync mechanism that syncs it with the NAS's operation status. When the NAS enters sleep mode or powers off, the AS6004U will enter into standby mode. When the NAS resumes normal operation, the AS6004U will resume mounting. This function works to help users save significant power.

Smart Power Saving

Smart Fan Temperature Control

Under heavy loading and operations, the system internal temperature will increase. The AS6004U utilizes fans with a wide speed range that support a temperature control function combined with a smart speed mechanism. When the system load and temperature increases, the fans will automatically increase their speed to cool the device allowing the system to maintain a suitable operation temperature, providing stable performance and service.

*Temperature will vary depending on the number hard disks installed and the brand.

HDD Temperature and Fan Speed

Smart Fan Temperature Control

Secure Storage

The AS6004U features 4 hot swappable disk bays and is compatible with largest hard disks on the market. It supports RAID* and AES 256-bit encryption, providing optimal data protection mechanisms.

*The AS6004U supports Single Disk, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10 volumes

Secure Storage
Secure Storage
Secure Storage

Flexible Storage Expansion and Backup

In addition to providing an economical high capacity storage space, the AS6004U also supports ASUSTOR's MyArchive cold backup technology. This allows users to create removable storage archives at any time, and backup important data to them.

Flexible Storage Expansion and Backup

First-Class Product Warranty

All ASUSTOR NAS products come with a 3-year warranty. ASUSTOR continues to make customer service a priority in providing the highest standard of after-sales service and technical support.

First-Class Product Warranty


Hardware Specifications
Flash Memory 16MB Flash
Expansion USB 3.0 (USB3.1 Gen-1) Type B
HDD 4 x SATA3 6Gb/s; 3.5"/2.5" HDD/SSD
Maximum Internal Raw Capacity 64 TB  (16 TB HDD X 4, Capacity may vary by RAID types)
Maximum Single Volume Size 16TB
Supports Hot Swappable Drives Yes
System Fan 120mm x1
Power Supply Unit / Adapter 90W x1
Input Power Voltage 100V to 240V AC
Certification FCC, CE, VCCI, BSMI, C-TICK
Power Consumption 23.6 W (Operation);
9.7 W (Disk Hibernation);
0.35 W (Sleep Mode)2
Operation Temperature 0°C~40°C (32°F~104°F)
Humidity 5% to 95% RH
Size and Weight
Size 185.5(H) x 170(W) x 230(D) mm
Weight 2.7 kg / 5.95 lbs
Package Contents
Package Contents
  • AS6004U Unit
  • Installation CD x1
  • AC Power Cord x1
  • AC Power Adapter x1
  • USB 3.0 Cable x1
  • Flat Head Screw (for 3.5" HDD) x16
  • Flat Head Screw (for 2.5" HDD) x16
  • USB 3.0 Cable Bracket x1
  • Power Cord Bracket x1

1 Hard disks not included.
2 Test HDD: WD Red 3 TB HDD
3 USB Wi-Fi dongle not included.
4 You must first enable real time transcoding for these files in order to play them.
5 Metadata (e.g. title) may not be able to displayed in iTunes.

Software & Features:

Operating System

  • ADM 3.1 Onwards

File System

  • Internal Disk: EXT4

Storage Management

  • Support Multiple Volumes with Spare Disks
  • Volume Type: Single disk, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10
  • Support for Online RAID Level Migration


  • Insert Hard Disk & Immediately Access Files
  • Transfer or Exchange Terabytes of Data via the Internal Hot-Swap SATA Interface
  • Up to N-1 Bays Reserved for MyArchive Docking Purposes


Angle View
Front View
Back View
Top Angle View

Pricing Notes:

Asustor Products
ASUSTOR Storage Array
ASUSTOR AS6004U 4-bay Expansion
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ASUSTOR AS6004U Storage Array Bundles
ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 1TB Hard Drive (QTY 4) 4TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 3TB Hard Drive (QTY 4) 12TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 4TB Hard Drive (QTY 4) 16TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 6TB Hard Drive (QTY 4) 24TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 8TB Hard Drive (QTY 4) 32TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 10TB Hard Drive (QTY 4) 40TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 12TB Hard Drive (QTY 4) 48TB Bundle
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ASUSTOR AS6004U 4-bay NAS with Seagate IronWolf 14TB Hard Drive (QTY 4) 56TB Bundle
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