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<br>
Romu,<br>
<br>
did you initialize the metadata device before trying to create the
era target?<br>
Zeroes in the first KBs will do.<br>
<br>
Yes, check for NULL in era_destroy is needed to handle the error
path you hit properly.<br>
<br>
Heinz<br>
<br>
<div class="moz-cite-prefix">On 09/26/2014 05:16 AM, Romu Hu wrote:<br>
</div>
<blockquote cite="mid:5424DA99.2070308@gmail.com" type="cite">
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On 2014/9/25 22:57, Heinz Mauelshagen wrote:<br>
<blockquote cite="mid:54242D6D.4090004@redhat.com" type="cite">
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
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>
</blockquote>
<br>
Sorry my bad.<br>
<br>
I ran 'dmsetup create MyEra --table "0 20971520 era
/dev/mapper/mpathbp1 /dev/mapper/mpathap1 8"' but kernel
(2.6.32-494.el6.i686) oopsed:<br>
<br>
<tt>Sep 25 18:34:11 localhost kernel: device-mapper: era: sb_check
failed: magic 0: wanted 2126579579</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: device-mapper: block
manager: superblock validator check failed for block 0</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: device-mapper: era:
couldn't read_lock superblock</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: BUG: unable to handle
kernel NULL pointer dereference at 00000008</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: IP: [<f7e2b3c7>]
era_destroy+0x7/0x60 [dm_era]Sep 25 18:34:11 localhost kernel:
*pdpt = 0000000032457001 *pde = 00000003fb5fa067</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: Oops: 0000 [#1] SMP</tt><tt><br>
</tt><tt>Sep 25 18:34:11 localhost kernel: last sysfs file:
/sys/module/dm_persistent_data/initstate</tt><br>
<br>
Perhaps this should be cherry-picked?<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=989f26f5ad308f40a95f280bf9cd75e558d4f18d">https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=989f26f5ad308f40a95f280bf9cd75e558d4f18d</a><br>
<br>
The log says sb_check failed, anything wrong with the dmsetup
command parameters?<br>
<br>
Thanks<br>
Romu<br>
<br>
<blockquote cite="mid:54242D6D.4090004@redhat.com" type="cite">
<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>
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<pre class="moz-signature" cols="72">--
===============================================================
Heinz Mauelshagen +49 2626 141200
Consulting Development Engineer FAX +49 2626 924446
Red Hat GmbH
Am Sonnenhang 11
56242 Marienrachdorf
Germany <a class="moz-txt-link-abbreviated" href="mailto:heinzm@redhat.com">heinzm@redhat.com</a>
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