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17 lines
795 B
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17 lines
795 B
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Durability
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~~~~~~~~~~
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Some devices may be considered to be more reliable than others. For
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example, we might have a filesystem composed of a hardware RAID array
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and several NVME flash devices, to be used as cache. We can set
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replicas=2 so that losing any of the NVME flash devices will not cause
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us to lose data, and then additionally we can set durability=2 for the
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hardware RAID device to tell bcachefs that we don’t need extra replicas
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for data on that device - data on that device will count as two
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replicas, not just one.
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The durability option can also be used for writethrough caching: by
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setting durability=0 for a device, it can be used as a cache and only as
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a cache - bcachefs won’t consider copies on that device to count towards
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the number of replicas we’re supposed to keep.
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