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Am Donnerstag 30 September 2010, 12:58:36 schrieb Adam Carter: |
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> Taring my mp3 collection from 2.5in 500MB internal sata drive (sda) to |
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> esata 3.5in 500MB drive (sdb) and it seems slow. In vmstat i can see that |
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> the external drive writes faster than the internal can read (external has |
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> periods of inactivity) |
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[...] |
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> So 21221MB in 610 seconds = 35 MB/s |
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> |
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> # hdparm -t /dev/sda |
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> |
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> /dev/sda: |
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> Timing buffered disk reads: 220 MB in 3.01 seconds = 73.14 MB/sec (77 |
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> with --direct) |
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[...] |
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> So the should i expect filesystem (reiser3) and other overhead to cut the |
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> read performance to less than half of what hdparm reports? Anything else i |
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> can look at to speed it up? Im using CFQ io scheduler. |
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|
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35 MB/s is a pretty normal value for a 5400 RPM laptop HDD. |
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|
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An HDD gets slower when you read the inner tracks. The angular velocity is |
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constant (5400 RPM) while the tangential velocity gets lower with the radius. |
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|
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Inner tracks are mapped to the sectors at the far end of the partition table. |
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That's why you should always put swap and system partitions at the front of |
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your partition table and use its end for bulk data. |
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|
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I guess your mp3 collection is stored somewhere at the middle or end of your |
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internal disk (inner tracks) while your external disk is nearly empty and |
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therefore stores data on the outer tracks. |
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|
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Hope this helps. |
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Florian Philipp |