I have a process that uses two disks. One disk is thrashed with both reads and writes. Currently they are SMR, not CMR, and I am transferring the data to CMR then, maybe, SSD. I need multiple terabytes so SSD is expensive. I tested the move to a Pi 5 without success.
The process runs on a cheap Intel notebook with any combination of two USB disks. I tested it on a Pi 5 with the official Pi 5 power supply and the magnetic disk drops out every so often. The disk remounts as read only. A fsck fixup takes a long time. I figure the dropout is the Pi 5 not handling the peak power requirements for the USB disks.
My recent tests used a power efficient SSD plus one 2.5" 4 TB SMR disk. The system fails within an hour. No pattern I can see.
The SSD is too small. I need 4 TB now and 8 TB soon. Are there 4 TB or 8 TB SSDs using the same or less power than current 1 TB SSDs?
Sometimes the disks fail to mount properly if I switch on the Pi 5 with both disks plugged in. Boot works reliably without disks or with just the SSD. Magnetic disks have a big peak when starting up. I am looking at alternatives without spending $900 for an 8 TB SSD.
I have an externally powered USB 3 hub I used when experimenting with a Pi 4. I have one 3.5" CMR disk in an externally powered enclosure that may be my next step so I can toss out one of the SMR disks. A 3.5" disk always on is a big power chewer and magnetic disks suffer when switched off/on all day. An SSD switches to low power faster but I do not know of a USB enclosure that switches power down the way a built in SSD switches down. The few enclosures mentioning a low power option say it switches on after 10 minutes. The disk is likely to have a blip every few minutes and never switch to low power.
The next option is to use the PCIe interface for a large capacity SSD, which means 2280, and one USB SSD. There are PCIe boards for 2 * 2280. 2 * 8 TB?
What do you use for very large disk capacity in a Pi 5?
The process runs on a cheap Intel notebook with any combination of two USB disks. I tested it on a Pi 5 with the official Pi 5 power supply and the magnetic disk drops out every so often. The disk remounts as read only. A fsck fixup takes a long time. I figure the dropout is the Pi 5 not handling the peak power requirements for the USB disks.
My recent tests used a power efficient SSD plus one 2.5" 4 TB SMR disk. The system fails within an hour. No pattern I can see.
The SSD is too small. I need 4 TB now and 8 TB soon. Are there 4 TB or 8 TB SSDs using the same or less power than current 1 TB SSDs?
Sometimes the disks fail to mount properly if I switch on the Pi 5 with both disks plugged in. Boot works reliably without disks or with just the SSD. Magnetic disks have a big peak when starting up. I am looking at alternatives without spending $900 for an 8 TB SSD.
I have an externally powered USB 3 hub I used when experimenting with a Pi 4. I have one 3.5" CMR disk in an externally powered enclosure that may be my next step so I can toss out one of the SMR disks. A 3.5" disk always on is a big power chewer and magnetic disks suffer when switched off/on all day. An SSD switches to low power faster but I do not know of a USB enclosure that switches power down the way a built in SSD switches down. The few enclosures mentioning a low power option say it switches on after 10 minutes. The disk is likely to have a blip every few minutes and never switch to low power.
The next option is to use the PCIe interface for a large capacity SSD, which means 2280, and one USB SSD. There are PCIe boards for 2 * 2280. 2 * 8 TB?
What do you use for very large disk capacity in a Pi 5?
Statistics: Posted by peterlite — Wed Jul 16, 2025 12:44 am