QNAP TS-531X

QNAP · NAS file server, 5 bays, 32-bit ARM processor · TS-531X

Generic drawing of the device class, not of this model

what it is

A file server with five drive bays, in a tower casing. According to the manufacturer datasheet it has a quad-core AnnapurnaLabs Alpine processor, two 10 GbE SFP+ ports and two gigabit ports; the system sees four interfaces eth0–eth3. Memory from 2 GB.

The processor is 32-bit (uname -m returns armv7l). This has a practical consequence: most container images are published today only for amd64 and arm64, so they will not start on this NAS — the error reads no matching manifest, not "unsupported architecture". The container environment is there; the images are missing.

The drawing above is a generic symbol for the server class, not the appearance of this model.

The system reports itself as TS-X31X, and as the internal model — TS-X41. The serial number is returned by neither getcfg nor getsysinfo, and the ARM processor has no DMI table. The number is on the label and in the QTS panel.

what we read from it

SNMP is disabled from the factory. Once enabled, the standard load branches (UCD-SNMP) are silent, but QNAP's own tree (enterprise number 24681) returns:

processor and memory: CPU usage, total and free memory, uptime,
system temperature — the CPU temperature sensor on this model returns 0, meaning it is absent,
bay table: name, disk temperature, model, capacity and SMART status (the word GOOD, no counters),
volume table: name, file system, size, free space and status,
network interfaces with counters — they duplicate the standard IF-MIB.

The same values appear twice in the tree. Branch 1.2 returns them as text with the unit inside ("11.30 %", "27 C/81 F"), branch 1.3 — as numbers ready for thresholds. A walk hits the text branch first.

Empty bays are also in the table and return spurious values: temperature 0, model and SMART --. An alarm "disk temperature = 0" or "SMART not equal to GOOD" will fire on a bay that never had a disk. An empty bay is recognized by the model --.

measured pitfalls

The factory SNMP file allows writes. snmpd.conf contains rwcommunity public next to rocommunity public. It has to be fixed before enabling SNMP.
The SNMP enable key is Service Enable. With Enable or Server Enable the startup script exits silently. The script is named /etc/init.d/snmp, without .sh.
The community is set in the file, not via setcfg — the daemon reads /etc/config/snmpd.conf and ignores the values from uLinux.conf.
A saved setting does not stop the service. getcfg FTP Enable returns FALSE, while the FTP server keeps listening on port 21. Every service change also has to be checked by looking at the listening port.
Package scripts are silent, because they redirect all output to their own log start-stop.log. Silence on the console says nothing about the outcome; qpkg_cli reports to the console.
Stopping a package takes a dozen or so seconds — a reading right after the command shows the state from before.
BusyBox 1.01 from 2018 does not know grep -m or grep -E and has no ethtool, lsblk, ss.
A root directory at 94% usage is normal — it is the system image in a fixed-size ramdisk. Space for updates is in /mnt/HDA_ROOT.

LVM pool under snapshots

Volumes sit on an LVM thin pool. With snapshots enabled, every write takes new blocks in the pool. When the pool reaches 100%, the volume switches to read-only mode.

df will not show it — it sees the volume, not the pool; we measured 77% on the volume with 90% in the pool.
Neither will SNMP — pool usage is not in any branch.
The reading comes from lvs -o lv_name,lv_size,data_percent,metadata_percent. Metadata has a separate counter, and exhausting it damages the pool irreversibly.

what we cannot read

LVM pool and metadata usage — neither over SNMP nor in df.
SMART counters — only a verbal rating.
Serial number from the system.
SFP+ port speed without a link — the system has no ethtool.

full parameter list

A full parameter list for this model is not here yet — the ones described above are those we have read and verified. A missing list does not mean the device exposes nothing more.