dm thin: relax hard limit on the maximum size of a metadata device

[deliverable/linux.git] / Documentation / device-mapper / thin-provisioning.txt

diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index 801d9d1cf82be56facc9a8e9f99b41d35739374a..a119fbdd0604402122c1a2991ab63c7af81d5273 100644 (file)
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -1,7 +1,7 @@
 Introduction
 ============
 
-This document descibes a collection of device-mapper targets that
+This document describes a collection of device-mapper targets that
 between them implement thin-provisioning and snapshots.
 
 The main highlight of this implementation, compared to the previous
@@ -75,10 +75,12 @@ less sharing than average you'll need a larger-than-average metadata device.
 
 As a guide, we suggest you calculate the number of bytes to use in the
 metadata device as 48 * $data_dev_size / $data_block_size but round it up
-to 2MB if the answer is smaller.  The largest size supported is 16GB.
+to 2MB if the answer is smaller.  If you're creating large numbers of
+snapshots which are recording large amounts of change, you may find you
+need to increase this.
 
-If you're creating large numbers of snapshots which are recording large
-amounts of change, you may need find you need to increase this.
+The largest size supported is 16GB: If the device is larger,
+a warning will be issued and the excess space will not be used.
 
 Reloading a pool table
 ----------------------
@@ -237,16 +239,6 @@ iii) Messages
 
        Deletes a thin device.  Irreversible.
 
-    trim <dev id> <new size in sectors>
-
-       Delete mappings from the end of a thin device.  Irreversible.
-       You might want to use this if you're reducing the size of
-       your thinly-provisioned device.  In many cases, due to the
-       sharing of blocks between devices, it is not possible to
-       determine in advance how much space 'trim' will release.  (In
-       future a userspace tool might be able to perform this
-       calculation.)
-
     set_transaction_id <current id> <new id>
 
        Userland volume managers, such as LVM, need a way to