mirror of https://github.com/schoebel/mars
user-manual: rework IO performance tuning
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@ -25070,6 +25070,12 @@ re-ordering of writeback
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transaction logfile, and even when both are residing at the same RAID set.
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\end_layout
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\begin_layout Standard
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Since RAID-6 is has more expensive write operations due to its CRC computations
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and updates, RAID-6 will much more profit from this effect.
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Other RAID modes like RAID-10 may show a lower throughput improvement.
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\end_layout
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\begin_layout Standard
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Notice: this effect is not only dependent from total RAM size and from the
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maximum size of the MARS temporary memory buffer (tuning parameter
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@ -25098,6 +25104,17 @@ dd
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is no appropriate benchmarking tool, and has almost nothing to do with
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real workloads occuring in datacenters, which typically are neither sequential,
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nor do they have a parallelism degree of only 1.
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\end_layout
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\begin_layout Standard
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\noindent
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\begin_inset Graphics
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filename images/MatieresCorrosives.png
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lyxscale 50
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scale 17
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\end_inset
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Please don't try to lead any discussions about this: simply use
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\family typewriter
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blktrace
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@ -25123,11 +25140,20 @@ dd
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\end_inset
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Any assumptions about workloads are very dangerous: they can deviate from
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practice not only by factors, but sometimes even by
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Any
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\series bold
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assumptions about workloads
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\series default
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are very dangerous: they can deviate from practice not only by factors,
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but sometimes even by
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\emph on
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orders of magnitude
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\emph default
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.
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There no substitute for real measuments of
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\series bold
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actual workload behaviour
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\series default
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.
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\end_layout
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