On 10/22/2019 06:47 AM, David Haller wrote:
larger and cheaper but definitely not safer. look on the net, consensus is for SSDs. For (long(ish) term) backups? No sirreee! Simple physics. A magnetised region will keep its alignment unless disturbed[1][2]. A NAND cell will inevitably lose it's "bitness" over time unless refreshed.
I've seen SSD's retain data when off-line for a year or so, but I agree that they shouldn't be used for long-term storage.
So, for cold storage "long-term" backups, rotating rust, or even better rust-on-nylon (aka tapes) or so is the way to go.
We've got hundreds of SATA spinning disks that have been off-line for more than six-years and we're going through them to make copies on new, higher capacity drives. So far, we had only one sector error that affected one file. But we were able to recover that from a second backup RAID6 array. But note that modern high-capacity drives are charged with helium to allow the heads to fly closer to the "rust". Now I'm worried about the helium leaking out! The drives are warrantied for 5-years, but that won't save lost data. As for tape, I don't trust it long-term. I remember back in the old "analog" days we recorded data on 1-inch AMPEX instrumentation tape. We tried to play back some acoustic data after the tape was on the shelf for about 10-years and discovered that the data was corrupted by a large amplitude "screeching" noise. We figured out that the iron oxide was coming loose and collecting on the read heads. This made the heads "sticky" which caused the tape to vibrate as it passed the heads. This vibration was the screeching noise. Lots of data lost. Regards, Lew -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org