Author Topic: Bit Rot on SSDs and Rust  (Read 970 times)


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Bit Rot on SSDs and Rust
« on: May 22, 2022, 12:57:00 AM »
There was a discussion a while back on 'bit rot' - losing data - on SSDs and spinning rust.

A few comments

  - I use a 4x2.5 inch enclosure fromOWC/MacSales to hold four 2.5 inch 2TB drives in each enclosure. These are connected to a spare Mac mini which acts as a file server (and runs Roon to serve music to the house). I use SoftRAID (same company) to organize - each set of 4 is a RAID drive. I use Carbon Copy Cloner to back up my work machine across the wired Ethernet to one of the , and the server itself backs up one RAID to the next.The one backed up to from the working machine is a mirror of a stripe (so 4TB); the backup of the backup is a RAID 5 (so 6TB).

  - I use BackBlaze to back up the RAID 5 - digitized music included - to the cloud. It takes a while to back it all up, but if your local machinery goes Ker-blooie and all your data is lost or suspect, it's a Good Thing. They'll send you a USB disk with everything on...

  - and I keep the disk that BackBlaze sent me. It's disconnected, doesn't have everything in, but should be good for an emergency recover [it's spinning rust - cheaper for them] - and to the specific point here, BackBlaze has many many disks. A lot. And they publish statistics on how they work and differing failure rates.

  - as to whether SSDs suffer bit rot - data degradation - when left unpowered, it appears [I've lost the reference] that if you keep your SSD unpowered at 40C for a year, you'll probably lose some bits. 40C is *** hot *** So *probably* you in real life are unlikely to lose data as an effect of unpowered SSDs. But if you're using some sort of tiered backup as I've described above, you'll never see it. Because your SSDs are powered on.
« Last Edit: May 22, 2022, 07:26:26 AM by Paul Sanders (AlpineSoft) »

Paul Sanders (AlpineSoft)

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Re: Bit Rot on SSDs and Rust
« Reply #1 on: May 22, 2022, 07:30:59 AM »
I use an SSD for my system disk and old-fashioned hard disks for data.  I backup my hard disks to a second drive in the same machine and I also backup the essential stuff to OneDrive, so as to have a copy offsite.  I have also tried to arrange things to minimise the amount of data I repeatedly write to the SSD, day-in day-out, since this definitely wears them out.

This strategy works well for me.  The SSD provides a welcome performance boost, especially booting up, and for data, regular drives are fine.


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Re: Bit Rot on SSDs and Rust
« Reply #2 on: July 14, 2022, 07:43:56 AM »
Thanks for the information.