Please do put me in cc list while replying.<br><br><div class="gmail_quote">On Tue, Nov 1, 2011 at 11:38 AM, Sanjana Shari <span dir="ltr"><<a href="mailto:sanjana.linux@gmail.com">sanjana.linux@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><span style="font-family:courier new,monospace">Hello,</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">I am trying to create two device mapper files for an underline blockdevice. One file( half1) will be mapped to the first half of the block-device. and the second half (half2) will be mapped to the rest of the space in the same block device.</span><br style="font-family:courier new,monospace">
<br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">1.Using dd command I have created a 100 MB file.</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace"># dd if=/dev/zero of=dm_test bs=512 count=204800</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">2. associated it with loop device:</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace"># losetup /dev/loop0 /tmp/dm_test</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace"># blockdev --getsize /dev/loop0</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">204800</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">using dmsetup to create dm file.</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace"># dmsetup create half --table "0 102400 linear /dev/loop0 0"</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">[root@bladelinux01 root]# dmsetup table half</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">0 102400 linear 7:0 0</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">[root@bladelinux01 root]# dmsetup info half</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Name: half</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">State: ACTIVE</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Read Ahead: 256</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">Tables present: LIVE</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Open count: 0</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">Event number: 0</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Major, minor: 253, 6</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">Number of targets: 1</span><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace"><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">[root@bladelinux01 root]# ls -l /dev/mapper/half</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">lrwxrwxrwx. 1 root root 7 Nov 1 01:44 /dev/mapper/half -> ../dm-6</span><br style="font-family:courier new,monospace">
<br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">But if I use the other part of the disk to map. The command is not successful</span><br style="font-family:courier new,monospace">
<br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">[root@bladelinux01 root]# dmsetup create half1 --table "102401 102399 linear /dev/loop0 102400"</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">device-mapper: reload ioctl failed: Invalid argument</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Command failed</span><br style="font-family:courier new,monospace">
<br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">[root@bladelinux01 root]# dmsetup create half1 --table "102401 102399 linear /dev/loop0 0"</span><br style="font-family:courier new,monospace">
<span style="font-family:courier new,monospace">device-mapper: reload ioctl failed: Invalid argument</span><br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">Command failed</span><br style="font-family:courier new,monospace">
<br style="font-family:courier new,monospace"><span style="font-family:courier new,monospace">The format used seems to be correct according to the man page of dmsetup. Please guide me. I am not sure what am I missing</span>.<br>
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<br>-- sanjana<br><br>
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