<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Romu,<br>
<br>
"dmsetup create MyEra --table "0 20971520 /dev/mapper/mpathbp1
/dev/mapper/mpathap1 8"<br>
<br>
should read<br>
<br>
dmsetup create MyEra --table "0 20971520 era /dev/mapper/mpathbp1
/dev/mapper/mpathap1 8"<br>
<br>
<br>
Heinz<br>
<br>
<div class="moz-cite-prefix">On 09/25/2014 04:02 PM, Romu wrote:<br>
</div>
<blockquote
cite="mid:CANoG8sWXjR5LmZvY2K1ebOr=kS+A=-EPveqh=XsqD0v6bWcc2g@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">2014-09-25 18:19 GMT+08:00 Heinz
Mauelshagen <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:heinzm@redhat.com" target="_blank">heinzm@redhat.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"><span class=""> On
09/25/2014 08:10 AM, Romu Hu wrote:<br>
<blockquote type="cite"> On 2014/9/24 12:10, Brassow
Jonathan wrote:<br>
<blockquote type="cite">On Sep 22, 2014, at 7:35 AM,
Romu wrote:
<div><br>
<blockquote type="cite"><span
style="border-collapse:separate;font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium">I
tried the following command to set up my era
target but the command immediately panics
the system and the system reboots.
<div><br>
</div>
<div># dmsetup create MyEra --table "0
41941903 era
/dev/mapper/VG-CacheDataLV_cmeta
/dev/mapper/VG-OriginLV 4096"<br>
</div>
<div><br>
</div>
<div>The metadata dev and the origin dev are
all part of a LVM cache LV.
VG-CacheDataLV_cmeta is the cache metadata
LV on the smaller and faster device,
VG-OriginLV is the origin LV on the faster
and slower device, 41941903 is the total
sector number of the device of OriginLV
(the LV takes 100% space of the device),
4096 is the block size of OriginLV, I have
run 'mkfs.ext4 /dev/mapper/VG-OriginLV'
before running the dmsetup command.<br>
</div>
<div><br>
</div>
<div>Below is the message in
/var/log/messages after running the
dmsetup comnmand:</div>
<div><br>
</div>
<div>kernel: device-mapper: era: sb_check
failed: magic 1623043: wanted <a
moz-do-not-send="true"
href="tel:2126579579"
value="+12126579579" target="_blank">2126579579</a><br>
</div>
<div>
<div>kernel: device-mapper: block manager:
superblock validator check failed for
block 0</div>
<div>kernel: device-mapper: era: couldn't
read_lock superblock</div>
</div>
<div><br>
</div>
<div><br>
</div>
<div>Any idea?</div>
</span><br>
</blockquote>
</div>
<br>
<div>Sorry, I haven't used dm-era yet. However,
it does appear that you are perhaps specifying
the wrong devices when creating the era device?
Looks like you might be allowing the era target
and the cache target to use the same metadata
area at the same time - causing them to corrupt
each other's metadata area?</div>
<div><br>
</div>
<div> brassow</div>
</blockquote>
<br>
I think the dmsetup command to set up an era target
should be something like this:<br>
<br>
<tt><span
style="border-collapse:separate;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium">#
dmsetup create MyEra --table "0 sector_number
era metadeta_dev origin_dev block_size"</span></tt><br>
<br>
My questions:<br>
<br>
1) How to calculate sector_number? According to <a
moz-do-not-send="true"
href="https://www.kernel.org/doc/Documentation/device-mapper/era.txt"
target="_blank">https://www.kernel.org/doc/Documentation/device-mapper/era.txt</a>,
I guess it should be (4 * nr_blocks) bytes +
buffers, but what is nr_blocks and what is buffers?<br>
</blockquote>
<br>
</span> No calculation: it's the size of your era target
in sectors. Typically "blockdev --getsz origin_dev"<span
class=""><br>
<br>
<blockquote type="cite"> 2) Any documentation for
dmsetup tables?<br>
</blockquote>
<br>
</span> Look for examples in the kernel source trees
Documentaion/device.mapper.<br>
<br>
table line syntax is: "start_sector length_in_sectors
<target> <target_arguments{0,N}>"<span
class=""><br>
<br>
<blockquote type="cite"> 3) Both my metadata_dev and
origin_dev are 10G partitions, is this all right?<br>
</blockquote>
<br>
</span> Metadata device size is plenty but that depends
on how many eras with how many updates you want to have.<span
class=""><br>
<br>
<blockquote type="cite"> 4) My origin_dev is a ext4
filesystem with a block size of 4096, so the
block_size in the command line should also be 4096?<br>
</blockquote>
<br>
</span> You may use 4096 = _8_ sectors, you used 4096
sectors = 2MB below.<br>
It's the granularity the era target housekeeps blocks
for.<span class=""><br>
<br>
<blockquote type="cite"> <br>
I tried the following command:<br>
<br>
<tt># dmsetup create MyEra --table "0 160000 era
/dev/mapper/mpathap1 /dev/mapper/mpathbp1 4096"</tt><br>
</blockquote>
<br>
</span> May not be same physical device for data and
metadata!<br>
If it is, thta'd explain your oops.<br>
<br>
<tt># dmsetup create MyEra --table "0 $(blockdev --getsz
</tt><tt><tt>/dev/mapper/mpathbp)</tt> era
whatever_disctinct_metadata_device
/dev/mapper/mpathbp1 8"</tt><br>
<br>
Would use 8 sector block size (which is tiny!) with
disctinct metadata and data devices (presumabyl your
ext4 sits on <tt>/dev/mapper/mpathbp1)</tt><span
class=""><font color="#888888"><br>
<br>
Heinz<br>
</font></span></div>
</blockquote>
<div><br>
</div>
<div>Heinz, thank you for your help!</div>
<div><br>
</div>
<div>My origin dev is 10G so total sector number
is 20971520. /dev/mapper/mpathbp1 (/dev/dm-6) is the
metadata dev, /dev/mapper/mpathap1 (/dev/dm-7) is the
origin dev, they are on different LUNs.</div>
<div><br>
</div>
<div>I tried the following commands:</div>
<div><br>
</div>
<div># dmsetup create MyEra --table "0 20971520
/dev/mapper/mpathbp1 /dev/mapper/mpathap1 8"<br>
</div>
<div># Target type name /dev/mapper/mpathbp1 is too long.</div>
<div>
<div># Command failed</div>
</div>
<div><br>
</div>
<div># dmsetup create MyEra --table "0 20971520 /dev/dm-6
/dev/dm-7 8"<br>
</div>
<div># device-mapper: reload ioctl on MyEra failed: Invalid
argument</div>
<div>
<div># Command failed</div>
</div>
<div><br>
</div>
<div>And when executing the second command I see the
following in /var/log/messages:</div>
<div><br>
</div>
<div>
<div>Sep 25 06:37:48 localhost kernel: device-mapper:
table: 253:8: /dev/dm-6: unknown target type</div>
<div>Sep 25 06:37:48 localhost kernel: device-mapper:
ioctl: error adding target to table</div>
<div>Sep 25 06:37:48 localhost multipathd: dm-8: remove
map (uevent)</div>
<div>Sep 25 06:37:48 localhost multipathd: dm-8: devmap
not registered, can't remove</div>
<div>Sep 25 06:37:48 localhost multipathd: dm-8: remove
map (uevent)</div>
<div>Sep 25 06:37:48 localhost multipathd: dm-8: devmap
not registered, can't remove</div>
</div>
<div><br>
</div>
<div>Then I run 'mkfs.ext4 /dev/dm-6' and tried the second
command again but got the same result.</div>
<div><br>
</div>
<div>Any idea?</div>
<div><br>
</div>
<div>Thanks</div>
<div>Romu</div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">--
dm-devel mailing list
<a class="moz-txt-link-abbreviated" href="mailto:dm-devel@redhat.com">dm-devel@redhat.com</a>
<a class="moz-txt-link-freetext" href="https://www.redhat.com/mailman/listinfo/dm-devel">https://www.redhat.com/mailman/listinfo/dm-devel</a></pre>
</blockquote>
<br>
</body>
</html>