Powering an SDD Full of Streamer Music – Extreme Reliability Nervousa

My home is set up with 4 Raspberry Pi based streamers with, hopefully, a 5th streamer in the future. In my case, I am using LMS on one of the Rpi as a server with an USB external hard drive holding all my music. Most of us streaming in our homes are doing something like this, whether the hard drive is located in a NAS, a Pi, or a computer of some kind.

Because of the size of all those music files, we dread the day that the hard drive fails or otherwise needs to be replaced. Well, that day has come for me. I have started getting gaps in the music data and I have traced it down to a slowly failing spinner.

The decision on whether to replace it with a spinner or an SSD isn't as clear as you might think. Any device (including SSDs) that use NAND memory, especially MLC, have a finite life of the number of writes before they start to lose data. Consumer SSDs are almost exclusively MLC and many of them have the higher 3 or 4 bits per cell which shortens write life even further. This is not a trivial difference. Single Level Cells, SLC, has 10 to 30 times the write life of a 2 level MLC from what information I can find online. For this reason, many computers use SSDs for the operating system and short term memory, but will also use a large spinner for back up so that you can recover if the SSD loses data. Apple even combines this and calls it a Fusion Drive.

With a big chunk of music data on my server drive, I first thought about getting another big spinner. But then I got to thinking about the idea that this drive is mostly used for reading data and the issue with cell wear is in writing. Some additional research suggests that, used in a primarily read only function, the life of an SSD is actually very long. So long, that there isn't data about when it would fail. Internally, an SSD will rewrite itself for error correction in the range of every 3 months to 1 year. If it only reads in between that time, applying the normal write life to that error correction rewrite would mean that the SSD would live far longer than I will. So maybe, an SSD as a music drive isn't a bad idea after all.

One expert kept emphasizing that this should be true assuming that the hard drive had a good power supply. It turns out that noise on the power supply can be high enough to generate random writes which shortens the write life of the SSD. Further searching found a guy who measured the power on the various USB lines of his computer and found spikes of over 100 mV. He also found more continuous noise over 50 mVp-p. Even if I wasn't thinking about write errors, I wouldn't like to have that much noise on my power supply. This gent went ahead and made a filter that reduced the noise down to 10's of mV.

The filter is a good approach, but I realized that I don't know the PSRR of an SSD and haven't found a spec. It is probably just nervousa, but I figure it would be worthwhile to have even cleaner power to that SSD.

Lets look at some numbers. That 100 mV noise is -34 dB from the 5VDC power for the USB. I found an independent test of the Rpi power supply that at 1A measured 110 mVp-p and 24 mVrms noise. That 110 mVp-p is like the spike of 100 mV, so its about -33 dB, but the rms number looks a little better at -46 dB.

I am using a Mean Well SGA12U24 to power my LX-mini Pass Analog crossover. In that circuit, it seems pretty quiet and was recommended by Nelson, so I was curious what the noise for it might be. The datasheet shows a maximum ripple + noise of 50 mVp-p or -40 dB max, but there is a caveat because the noise is measured at 20MHz. Also, the Pass circuit is sure to have pretty high PSRR.

In contrast, I have a Squeezebox PSU (designed by Jean-Paul at DIYaudio) which is a regulated linear supply with low noise designed for 5VDC up to 3A. It measures noise of 0.1 mVrms or -94 dB. I admit that I am skipping back and forth between rms and p-p and comparing spike noise to average noise, but there still appears to be a clear advantage to a well designed, low noise, linear power supply over a computer USB channel or an inexpensive switcher. The only question is whether the life of the SSD is really improved by this level of lower noise. In the spirit of extreme nervousa, I'm willing to go there.

All I need is a good linear supply and to make a USB cable that sends the data to the computer and powers the SSD from the linear supply. That's easy. Now where is my xacto knife and soldering iron?

 

You are right about power supplies. An external spinner in a poorly powered case can sound pretty bad versus a better ps and case. My listening tests of internal ssd (non os) vs external ethernet connected spinner come out about equal or just a slight nod to the spinner.

I used to have a separate server for my hp setup connected to player computer via Ethernet, but have pressed an older Asus router into service and just hooked up a big 2TB drive (which is my backup for my main spkr data drive ). With no wifi on and an Ethernet connection to the player computer, it is a good as I have experienced in my setups.

Good luck with your journey!

 

As I take a break from my Azure certification preparations, I can't help but wonder if cloud storage would provide any benefits for home streaming vs. SSD/HDD platforms? Specifically, playing music from a low-latency (if that exists) cloud-storage platform like OneDrive or Dropbox.

Yes, the buffering would be a nightmare (depending on your network connection), but who wouldn't want to avoid drive replacements going forward (with the exception of cold storage for your music)? I know I'm pretty much done with dealing with my NAS' habit of cooking HDD's.

Although I suppose the argument to migrate exclusively to streaming services would defeat any reason to store/play music files from cloud storage.

Thoughts? Though a long buffer time before playing would drive me nuts.

 

I don't know of a consumer based cloud that would be low latency. I do know Google Drive zips everything, so that would not work. Not sure of the rest, but how many sites do not charge for over a TB of space? Besides, how hard it might be to give your player software an unchanging path to the files or library.

As for drives dying. I have been using some for 8 plus years. Yes occasional the index gets corrupt but then I reformat and restore from a backup. If your NAS is cooking drives get rid of that NAS, its garbage. My standalone powered enclosures ( and fanless ) last for a long time. Have not had a drive fail completely in 10 years or more. And spinners are dirt cheap nowadays. Makes total sense to keep 1-2 gens of backups, IMHO.

 

If you haven't had an HDD fail in 10 years, that's great. My Synology NAS has fan settings that can be set in software, but I don't think it's solely to blame for some of the drive failures.

However, I have to measure the maintenance costs of a NAS (including HDD/SSD replacements) vs. just paying for the cloud storage outright with what I'd be sinking into the NAS. That latency though...

 

why use a nas at all for your music library? You could just use a cheap router for an external usb drive and dedicate it to your music computer. Unless you have lots of drives for different things and/or want access from a number of computers. I keep my entire music library in two places on separate drives just in case, but that may not work if you want everything centralized.

 

I have 4 HDD's and a hot spare, and the redundancy has already saved my array once (although I had to scramble to order another WD Red replacement).

I have a NAS because keeping data on a single HDD is asking for trouble. That comes from 24 years of work experience/suffering and I'd like to avoid that drama when I get home.

 

My experience may not be universal, but I find that my 10 year old hard drives are still alive, but my 3 to 5 year old hard drives are dying. Unfortunately, I didn't buy 1TB drives 10 years ago, so that includes my music drives.

I tend to agree that a NAS is an older form of storage and you may be better off with a local hard drive like a USB. I even have a friend that is using a 2 TB NVMe attached to an RPi4. That said, I totally understand your desire to avoid data drama at home.

As for cold storage of data, including music, the spinners get the nod for that. Either spinners or your cloud storage or both. SSD or any NAND storage tends to forget over time. If they are not plugged in, they will still decay. If they don't have power to rewrite themselves from time to time, you will lose data. The consumer SSD standard is a certain amount of data loss after 1 year at 70 degrees F. Other temperatures are worse, but I can't remember if its hot or cold that they don't like.

The main thing here is that we shouldn't consider any digital storage as permanent and we need to learn what is going on in each technology so that we can choose our data source wisely.

 

Not saying NAS is bad at all, and something like Synology should be good. I do believe drives vary a bit in longevity. I think my 1TB drives are old Hitachis that have a good rep. Then I moved to 2TB Spinpoints by Samsung IIRC.
In any case, yea, data is destructive and nothing will last forever.

 

If you want to make a hobby out of this, go ahead. It'll probably be fun.

But if you just want reliable storage, these are solved problems. It's really simple:

1. If your music is worth much more than the cost of its disk storage, you need an offsite backup.

2. If high availability is important -- like you don't want to be without music while you restore from backup after a drive failure -- you need a RAID.

If you have those things, the implementation details (especially of things like your SSD power supply) don't really matter. Your RAID can be a hardware-managed RAID1 array in a PC, or a software-managed RAID6 array in a NAS, or a second local drive that you periodically sync to, or any other redundant arrangement. And your offsite backup can be cloud storage, or a NAS at a friend's house, or a mirrored drive that you keep at work and occasionally swap with your synced redundant copy at home, or any other backup that's separate from your redundant storage.

The actual implementation only changes the balance between quality (i.e., the freshness of your backup and the seamlessness of your RAID switchover), convenience (the ease of managing the RAID synchronization and updating your backup), and cost. So just choose the balance that works best for you. And btw, flash endurance is not an issue in this application, so don't worry about SSD write cycles.

FWIW, my setup is a local 16TB RAID6 NAS that backs itself up to a remote NAS every night using rsnapshot. A big advantage is that my LMS runs on the NAS itself, so I get MUCH higher performance and reliability than I would from a Raspberry Pi or a consumer router or whatever. And everything else in the house is backed up to the local NAS, too, so the cost of the setup -- approximately the price of a high-end DAC or pair of headphones -- is amortized over the benefit of protecting all that other data as well as the music.

 

@fastfwd - It sounds like you've got a good system that works well for you. And I don't disagree with anything you have said. As I sort of admit by titling this "extreme ........... nevrousa", this project is to learn and for fun. I also don't mind that I already have the pieces to make the SSD power supply work, so it doesn't really cost anything.

That said, I was working this evening on one of those backups, an off-site stored spinner.

None of my other drives will do, so buying a new spinner is needed and I went looking for reliability information. New information to me, Backblaze is a cloud storage company that shares reliability stats on thousands of data hard drives by model number. Of course, the data changes over time, but it looks like Seagate is having a reliability glitch or something and the HGST line is currently the best reliability. Nice to have that kind of data available.