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No need to power or refresh, but if you have a cruddy SSD you should keep other backups.

by bifrost 11y ago

ChrisLomont 11y ago
SSDs should suffer the same bit-rot other flash does. JEDEC specs require that a drive that has used 10% of its rewrite capacity it should hold the data for at least 10 years, and this decreases to when a drive has used 100% of its rewrite capacity it should hold the data for at least one year. So to meet specs a consumer drive should fall in between these timeframes. However, cheaper drives may well not completely meet this spec; this is common for many other manufacturing processes. The bit rot also depends on many other factors, the most important being temperature (you cannot outwit statistical mechanics). The next one is a combination of hot neutrons causing bit flips from impurities in the material and from cosmic rays, the latter of which can be reduced by choosing better storage locations. Better controllers could understand the decay modes and read and rewrite data to maximize expected lifetime, so power is needed for maximal expected lifetime. In practice, all of this is not of much use to everyday people [1]. But if you want to maximize your data retention, study all these issues. Here's a case the authors claim bit rot happened in three months offline [2]. [1] http://www.anandtech.com/show/9248/the-truth-about-ssd-data-retention http://www.anandtech.com/show/9248/the-truth-about-ssd-data-... [2] http://www.maximumpc.com/jedec-your-ssd-needs-power-source-avoid-losing-data-2015/ http://www.maximumpc.com/jedec-your-ssd-needs-power-source-a...
throwaway7767 11y ago
> No need to power or refresh, but if you have a cruddy SSD you should keep other backups. No need to power or refresh, but if you have data you value you should keep backups. Seriously, no matter where you are keeping your data, if you don't have a completely independent copy somewhere, you will lose it some day.

No need to power or refresh, but if you have a cruddy SSD you should keep other backups.

by bifrost 11y ago

No need to power or refresh, but if you have a cruddy SSD you should keep other backups.

SSDs should suffer the same bit-rot other flash does. JEDEC specs require that a drive that has used 10% of its rewrite capacity it should hold the data for at least 10 years, and this decreases to when a drive has used 100% of its rewrite capacity it should hold the data for at least one year. So to meet specs a consumer drive should fall in between these timeframes. However, cheaper drives may well not completely meet this spec; this is common for many other manufacturing processes. The bit rot also depends on many other factors, the most important being temperature (you cannot outwit statistical mechanics). The next one is a combination of hot neutrons causing bit flips from impurities in the material and from cosmic rays, the latter of which can be reduced by choosing better storage locations. Better controllers could understand the decay modes and read and rewrite data to maximize expected lifetime, so power is needed for maximal expected lifetime. In practice, all of this is not of much use to everyday people [1]. But if you want to maximize your data retention, study all these issues. Here's a case the authors claim bit rot happened in three months offline [2]. [1] http://www.anandtech.com/show/9248/the-truth-about-ssd-data-retention http://www.anandtech.com/show/9248/the-truth-about-ssd-data-... [2] http://www.maximumpc.com/jedec-your-ssd-needs-power-source-avoid-losing-data-2015/ http://www.maximumpc.com/jedec-your-ssd-needs-power-source-a...

throwaway7767 11y ago

> No need to power or refresh, but if you have a cruddy SSD you should keep other backups. No need to power or refresh, but if you have data you value you should keep backups. Seriously, no matter where you are keeping your data, if you don't have a completely independent copy somewhere, you will lose it some day.