From: Austin Chang <austin880625@gmail.com>
To: dm-devel@redhat.com
Cc: Austin Chang <austin880625@gmail.com>,
Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] dm-cache: document zeroing metadata device step
Date: Mon, 13 Jul 2020 03:40:39 +0800 [thread overview]
Message-ID: <20200712194039.329035-1-austin880625@gmail.com> (raw)
Inform dmsetup users to zero the first 4k of the metadata device at
cache creation in examples, just as mentioned in thin-provisioning
documentation. Instructions to use lvmcache for end users may be added
as well.
Link: https://www.redhat.com/archives/dm-devel/2013-April/msg00124.html
Signed-off-by: Austin Chang <austin880625@gmail.com>
---
Documentation/admin-guide/device-mapper/cache.rst | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/Documentation/admin-guide/device-mapper/cache.rst b/Documentation/admin-guide/device-mapper/cache.rst
index f15e5254d05b..ef9a82d50d19 100644
--- a/Documentation/admin-guide/device-mapper/cache.rst
+++ b/Documentation/admin-guide/device-mapper/cache.rst
@@ -330,6 +330,10 @@ https://github.com/jthornber/device-mapper-test-suite
::
+ # When using dmsetup directly instead of volume manager like lvm2,
+ # the first 4k of the metadata device should be zeroed to indicate
+ # empty metadata.
+ dd if=/dev/zero of=/dev/mapper/metadata bs=4k conv=notrunc
dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
/dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
--
2.26.2
next reply other threads:[~2020-07-12 19:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-12 19:40 Austin Chang [this message]
2020-07-12 19:59 ` [PATCH] dm-cache: document zeroing metadata device step Matthew Wilcox
2020-07-12 21:10 ` Austin Chang
2020-07-12 21:47 ` [PATCH v2] " Austin Chang
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