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Sven Köhler wrote: |
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> Hi, |
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> |
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> sorry for the silly subject, but did you ever experience the following?: |
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> |
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> i have a fileserver, i copy a file to it - let's say 600MB. |
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> |
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> So about every 200MB (i guess the linux box writes the data into the |
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> cache in the RAM first) linux writes the harddisk. But during that time |
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> - during the time it writes that 200MB to disk, there is no chance for |
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> any other IO. I'm playing an mp3 from the very same fileserver. It stops |
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> playing, because the machine does answer the read-requests. |
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> |
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> So what's going on here? |
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> |
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> Why does Linux write so huge amounts of data to the disk? Why does Linux |
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> not stop writing for a while to fullfil the read-requests? And so on ... |
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> |
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> Any idea, on how to imrpove that? |
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> |
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|
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Perhaps a more often flush of buffers may help you in this situation. |
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|
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There are several parameters you can tweak to control your kernel |
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behavior regarding this. |
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|
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You can put the following lines in your /etc/sysctl.conf file, replacing |
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"i","j","k" and "l" with proper numbers. |
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vm.dirty_expire_centisecs = i |
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vm.dirty_writeback_centisecs = j |
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vm.dirty_ratio = k |
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vm.dirty_background_ratio = l |
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|
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The meaning of these parameters is descibed in the kernel documentation: |
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/usr/src/linux/Documentation/filesystems/proc.txt |
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/usr/src/linux/Documentation/sysctl/vm.txt |
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|
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You could also disable all write caching by issuing the command: |
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|
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hdparm -W0 /dev/<your-physical-disk-name> |
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|
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|
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Hope This Helps |
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|
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--- |
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Best regards |
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Daniel |
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-- |
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