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Yang, Tong
6182f91ba8
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: Yang, Tong <yangtong2@huawei.com> Co-committed-by: Yang, Tong <yangtong2@huawei.com>
35 lines
2.6 KiB
HTML
35 lines
2.6 KiB
HTML
<a name="mrs_01_1697"></a><a name="mrs_01_1697"></a>
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<h1 class="topictitle1">Failed to Calculate the Capacity of a DataNode when Multiple data.dir Directories Are Configured in a Disk Partition</h1>
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<div id="body1597735019227"><div class="section" id="mrs_01_1697__sc5ac855dc13c4238ae97e288d3603be0"><h4 class="sectiontitle">Question</h4><p id="mrs_01_1697__a85a7ea273178439ca07fca145a5a2a70">The capacity of a DataNode fails to calculate when multiple data.dir directories are configured in a disk partition.</p>
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</div>
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<div class="section" id="mrs_01_1697__sc10477ce58bf4114bd1b7e41c4e9518a"><h4 class="sectiontitle">Answer</h4><p id="mrs_01_1697__a5a86dbca5dc34817b419aa91a5eda2a7">Currently, the capacity is calculated based on disks, which is similar to the <i><b><span class="cmdname" style="font-family:Arial" id="mrs_01_1697__cmdname74669281056">df</span></b></i> command in Linux. Ideally, users do not configure multiple data.dir directories in a disk partition. Otherwise, all data will be written to the same disk, greatly deteriorating the performance.</p>
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<p id="mrs_01_1697__a7e43ab20c83e4d6b92b1beae06a468b5">You are advised to configure them as below.</p>
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<p id="mrs_01_1697__adffd0a6cc3d04408b3ce840679e4b8ea">For example, if a node contains the following disks:</p>
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<pre class="screen" id="mrs_01_1697__se4303a5dbb2644e8aa5f7bdc077cf585">host-4:~ # df -h
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Filesystem Size Used Avail Use% Mounted on
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/dev/sda1 352G 11G 324G 4% /
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udev 190G 252K 190G 1% /dev
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tmpfs 190G 72K 190G 1% /dev/shm
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/dev/sdb1 2.7T 74G 2.5T 3% /data1
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/dev/sdc1 2.7T 75G 2.5T 3% /data2
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/dev/sdd1 2.7T 73G 2.5T 3% /da</pre>
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<p id="mrs_01_1697__a9689806efc5e45079f73784cfe467ac1">Recommended configuration:</p>
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<pre class="screen" id="mrs_01_1697__se4c7cd09d99a4a70a7a5ef6a8a233fba"><property>
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<name>dfs.datanode.data.dir</name>
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<value>/data1/datadir/,/data2/datadir,/data3/datadir</value>
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</property></pre>
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<p id="mrs_01_1697__afb4c974feac845adb33a7babddbf67c7">Unrecommended configuration:</p>
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<pre class="screen" id="mrs_01_1697__s5b13f3dbf42641819f0b5336d2cd459c"><property>
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<name>dfs.datanode.data.dir</name>
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<value>/data1/datadir1/,/data2/datadir1,/data3/datadir1,/data1/datadir2,data1/datadir3,/data2/datadir2,/data2/datadir3,/data3/datadir2,/data3/datadir3</value>
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</property></pre>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="mrs_01_1690.html">FAQ</a></div>
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</div>
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</div>
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