Tech

Raspberry Pi: Retrofitting SATA with ease


The SD card of a Raspberry Pi is not ideal for data storage. While SSDs are satisfied with a USB adapter to SATA, this economical solution is not enough for mechanical hard drives. We tested different options.

For smaller or temporary file storage in the network, an older Raspberry Pi with a generous SD card or even better with a USB stick without additional accessories is completely sufficient.

Raspberry Pi OS
(formerly Raspbian) also provides the Samba server for the CIFS / SMB protocol in its package sources in order to provide Windows shares. The setup as a file server is no different than with a regular Debian. A reliable Linux system alone doesn’t make a file server, let alone a generous NAS. With the

Raspberry Pi 4
With real Gigabit Ethernet and faster USB 3.0 ports, this application appears more attractive than with the previous models. But what the Raspberry Pi still lacks is a SATA connection for connecting SATA hard drives. Various approaches tested here can compensate for this shortcoming.

Simple adapter: USB to SATA

Simple adapter: The Raspberry Pi 4 delivers a maximum of 1.2 A via USB. It is sufficient for small notebook hard drives up to two TB and economical SSDs. Other drives need a power supply.

Enlarge

Simple adapter: The Raspberry Pi 4 delivers a maximum of 1.2 A via USB. It is sufficient for small notebook hard drives up to two TB and economical SSDs. Other drives need a power supply.

© Sabrent

The simplest solution are passive adapters that simply lead all SATA connectors including the power supply for the external data carrier to the USB port. Adapters of this type are already

from seven euros plus shipping costs
to have. However, these accessories do not have their own power supply unit – the USB port must provide the required power. In principle, this already works from the Raspberry Pi 2, because from this model the USB ports deliver up to 1.2 A. This applies to all ports combined. A single USB connection is not limited, but supplies a connected device with a maximum of this current. The specification is

in the documentation of the Raspberry Pi Foundation
set out. In practice, this power supply is sufficient for a single SSD or a 2.5-inch hard drive up to two TB. However, you cannot operate more than one SATA drive via USB and USB power supply – even the Raspberry Pi 4 becomes unstable when it is supposed to supply two USB drives with power.

With power supply: SATA docks

With its own power supply unit: 3.5-inch drives and 2.5-inch hard drives from two TB cannot be supplied via USB and require a separate power supply.

Enlarge

With its own power supply unit: 3.5-inch drives and 2.5-inch hard drives from two TB cannot be supplied via USB and require a separate power supply.

© Inateck

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If the Raspberry 4 is to address more than one SATA drive via USB, docking stations for 2.5-inch or 3.5-inch hard drives with a USB connection are an option. Corresponding devices are available

by mail order from 25 euros
or

with two inserts from 30 euros
. An alternative that is a few euros cheaper

small plug-on adapter with its own power supply unit
that fit better in tight spaces and in drawers. In this way, two SATA drives can be connected to the Raspberry Pi 4 via the fast USB port.

Attention:

The included power supplies, which are often made very cheaply, usually have a very poor level of efficiency and increase the energy requirement per hard drive by around four to six watts.

Raspberry Pi 4 as desktop:

Suitable for everyday use or not?

SATA boards: Permanently mounted

A general disadvantage of adapters and docks in cramped conditions are the cable tangles that quickly get out of hand. In the long run, these are always a source of error that should not be underestimated.

A slightly more expensive, but tidier third way to give the Raspberry Pi 4 a SATA connection is to use compact additional boards. As a sandwich, these bring together the adapter circuit, a 2.5-inch drive and the actual circuit board computer. These SATA boards are also connected with a jumper to one of the USB 3.0 ports for data transfer, because the GPIO pins are generally not suitable for high bandwidths.

The board shown in the lead picture of this post

Geekworm X825
(40 euros) can make a 2.5-inch drive available via the USB port of the Raspberry Pi 4 in this space-saving way. For more stable operation or a power-hungry hard drive with more than two TB, this board must be operated with an additional power supply unit for 5V / 4A (DC), which is not included in the scope of delivery and must be ordered separately. The highlight here is that the Raspberry Pi is also attached to this power supply unit and is also supplied via the corresponding GPIO pins.

In the past few months online shops have been promoting the Raspberry plug-in boards from Radxa Limited from Shenzhen, China. The products with the name Dual-SATA-HAT and Quad-SATA-HAT should give a Raspberry Pi 4 two or even four SATA connections. An obviously identical circuit board is also represented in online shops as Seeed Studio Dual SATA HAT. However, not a single one of these boards could be found in Germany or in the relevant online shops. Other online retailers in Europe canceled the order after a few weeks without further comment. According to our research, it can be assumed that these HATs were only manufactured in small numbers that did not even make it onto the local market.

Raspberry Pi stays cool:

Tips for cooling the mini PC

Raid: Only level 1 makes sense

A Raid-1 network, i.e. a mirroring of written data on two data carriers, could not be done well in practice on the previous Raspberry Pis because the board did not deliver enough performance. Our tests with a Raspberry Pi 3 B and two 3.5-inch hard drives in a Raid-0 network, each with its own power supply, show the first errors in the kernel protocol after about a day of operation. With the Raspberry Pi 4, USB 3.0 and more computing power, the operation of two hard drives as Raid 1 becomes realistic (mirroring). During a raid rebuild, however, the board is busy for hours and should have good cooling. Raid 5 (parity) demands too much computing power from the small circuit board, while Raid 0 (striping) does not bring any measurable advantages in terms of access speeds at the USB port.

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