snapshot: new XML for external system checkpoint

Each <domainsnapshot> can now contain an optional <memory> element that describes how the VM state was handled, similar to disk snapshots. The new element will always appear in output; for back-compat, an input that lacks the element will assume 'no' or 'internal' according to the domain state. Along with this change, it is now possible to pass <disks> in the XML for an offline snapshot; this also needs to be wired up in a future patch, to make it possible to choose internal vs. external on a per-disk basis for each disk in an offline domain. At that point, using the --disk-only flag for an offline domain will be able to work. For some examples below, remember that qemu supports the following snapshot actions: qemu-img: offline external and internal disk savevm: online internal VM and disk migrate: online external VM transaction: online external disk ===== <domainsnapshot> <memory snapshot='no'/> ... </domainsnapshot> implies that there is no VM state saved (mandatory for offline and disk-only snapshots, not possible otherwise); using qemu-img for offline domains and transaction for online. ===== <domainsnapshot> <memory snapshot='internal'/> ... </domainsnapshot> state is saved inside one of the disks (as in qemu's 'savevm' system checkpoint implementation). If needed in the future, we can also add an attribute pointing out _which_ disk saved the internal state; maybe disk='vda'. ===== <domainsnapshot> <memory snapshot='external' file='/path/to/state'/> ... </domainsnapshot> This is not wired up yet, but future patches will allow this to control a combination of 'virsh save /path/to/state' plus disk snapshots from the same point in time. ===== So for 1.0.1 (and later, as needed), I plan to implement this table of combinations, with '*' designating new code and '+' designating existing code reached through new combinations of xml and/or the existing DISK_ONLY flag: domain memory disk disk-only | result ----------------------------------------- offline omit omit any | memory=no disk=int, via qemu-img offline no omit any |+memory=no disk=int, via qemu-img offline omit/no no any | invalid combination (nothing to snapshot) offline omit/no int any |+memory=no disk=int, via qemu-img offline omit/no ext any |*memory=no disk=ext, via qemu-img offline int/ext any any | invalid combination (no memory to save) online omit omit off | memory=int disk=int, via savevm online omit omit on | memory=no disk=default, via transaction online omit no/ext off | unsupported for now online omit no on | invalid combination (nothing to snapshot) online omit ext on | memory=no disk=ext, via transaction online omit int off |+memory=int disk=int, via savevm online omit int on | unsupported for now online no omit any |+memory=no disk=default, via transaction online no no any | invalid combination (nothing to snapshot) online no int any | unsupported for now online no ext any |+memory=no disk=ext, via transaction online int/ext any on | invalid combination (disk-only vs. memory) online int omit off |+memory=int disk=int, via savevm online int no/ext off | unsupported for now online int int off |+memory=int disk=int, via savevm online ext omit off |*memory=ext disk=default, via migrate+trans online ext no off |+memory=ext disk=no, via migrate online ext int off | unsupported for now online ext ext off |*memory=ext disk=ext, via migrate+transaction * docs/schemas/domainsnapshot.rng (memory): New RNG element. * docs/formatsnapshot.html.in: Document it. * src/conf/snapshot_conf.h (virDomainSnapshotDef): New fields. * src/conf/domain_conf.c (virDomainSnapshotDefFree) (virDomainSnapshotDefParseString, virDomainSnapshotDefFormat): Manage new fields. * tests/domainsnapshotxml2xmltest.c: New test. * tests/domainsnapshotxml2xmlin/*.xml: Update existing tests. * tests/domainsnapshotxml2xmlout/*.xml: Likewise.
2025-01-09 01:18:00 +03:00 · 2012-10-23 17:12:23 +02:00 · 2012-10-23 17:12:23 +02:00 · 4201a7ea1c
commit 4201a7ea1c
parent e66bdbb784
15 changed files with 162 additions and 9 deletions
--- a/docs/formatsnapshot.html.in
+++ b/docs/formatsnapshot.html.in
@ -24,7 +24,7 @@
        since the snapshot in a single file) and external (the
        snapshot is one file, and the changes since the snapshot are
        in another file).</dd>
-      <dt>VM state</dt>
+      <dt>memory state (or VM state)</dt>
      <dd>Tracks only the state of RAM and all other resources in use
        by the VM.  If the disks are unmodified between the time a VM
        state snapshot is taken and restored, then the guest will
@ -33,7 +33,7 @@
        corruption.</dd>
      <dt>system checkpoint</dt>
      <dd>A combination of disk snapshots for all disks as well as VM
-        state, which can be used to resume the guest from where it
+        memory state, which can be used to resume the guest from where it
        left off with symptoms similar to hibernation (that is, TCP
        connections in the guest may have timed out, but no files or
        processes are lost).</dd>
@ -41,7 +41,7 @@

    <p>
      Libvirt can manage all three types of snapshots.  For now, VM
-      state snapshots are created only by
+      state (memory) snapshots are created only by
      the <code>virDomainSave()</code>, <code>virDomainSaveFlags</code>,
      and <code>virDomainManagedSave()</code> functions, and restored
      via the <code>virDomainRestore()</code>,
@ -106,6 +106,17 @@
        description is omitted when initially creating the snapshot,
        then this field will be empty.
      </dd>
+      <dt><code>memory</code></dt>
+      <dd>On input, this is an optional request for how to handle VM
+        memory state.  For an offline domain or a disk-only snapshot,
+        attribute <code>snapshot</code> must be <code>no</code>, since
+        there is no VM state saved; otherwise, the attribute can
+        be <code>internal</code> if the memory state is piggy-backed with
+        other internal disk state, or <code>external</code> along with
+        a second attribute <code>file</code> giving the absolute path
+        of the file holding the VM memory state.  <span class="since">Since
+        1.0.1</span>
+      </dd>
      <dt><code>disks</code></dt>
      <dd>On input, this is an optional listing of specific
        instructions for disk snapshots; it is needed when making a
@ -172,7 +183,7 @@
        to <code>virDomainRevertToSnapshot()</code>.  Additionally,
        this field can be the value "disk-snapshot"
        (<span class="since">since 0.9.5</span>) when it represents
-        only a disk snapshot (no VM state), and reverting to this
+        only a disk snapshot (no VM memory state), and reverting to this
        snapshot will default to an inactive guest.  Readonly.
      </dd>
      <dt><code>parent</code></dt>
@ -222,6 +233,7 @@
  &lt;parent&gt;
    &lt;name&gt;bare-os-install&lt;/name&gt;
  &lt;/parent&gt;
+  &lt;memory snapshot='no'/&gt;
  &lt;disks&gt;
    &lt;disk name='vda' snapshot='external'&gt;
      &lt;driver type='qcow2'/&gt;
--- a/docs/schemas/domainsnapshot.rng
+++ b/docs/schemas/domainsnapshot.rng
@ -30,6 +30,29 @@
            <text/>
          </element>
        </optional>
+        <optional>
+          <element name='memory'>
+            <choice>
+              <attribute name='snapshot'>
+                <choice>
+                  <value>no</value>
+                  <value>internal</value>
+                </choice>
+              </attribute>
+              <group>
+                <optional>
+                  <attribute name='snapshot'>
+                    <value>external</value>
+                  </attribute>
+                </optional>
+                <attribute name='file'>
+                  <ref name='absFilePath'/>
+                </attribute>
+              </group>
+            </choice>
+            <empty/>
+          </element>
+        </optional>
        <optional>
          <element name='disks'>
            <zeroOrMore>
--- a/src/conf/snapshot_conf.c
+++ b/src/conf/snapshot_conf.c
@ -94,6 +94,7 @@ void virDomainSnapshotDefFree(virDomainSnapshotDefPtr def)
    VIR_FREE(def->name);
    VIR_FREE(def->description);
    VIR_FREE(def->parent);
+    VIR_FREE(def->file);
    for (i = 0; i < def->ndisks; i++)
        virDomainSnapshotDiskDefClear(&def->disks[i]);
    VIR_FREE(def->disks);
@ -182,6 +183,9 @@ virDomainSnapshotDefParseString(const char *xmlStr,
    int active;
    char *tmp;
    int keepBlanksDefault = xmlKeepBlanksDefault(0);
+    char *memorySnapshot = NULL;
+    char *memoryFile = NULL;
+    bool offline = !!(flags & VIR_DOMAIN_SNAPSHOT_PARSE_OFFLINE);

    xml = virXMLParseCtxt(NULL, xmlStr, _("(domain_snapshot)"), &ctxt);
    if (!xml) {
@ -243,6 +247,8 @@ virDomainSnapshotDefParseString(const char *xmlStr,
                           state);
            goto cleanup;
        }
+        offline = (def->state == VIR_DOMAIN_SHUTOFF ||
+                   def->state == VIR_DOMAIN_DISK_SNAPSHOT);

        /* Older snapshots were created with just <domain>/<uuid>, and
         * lack domain/@type.  In that case, leave dom NULL, and
@ -270,11 +276,42 @@ virDomainSnapshotDefParseString(const char *xmlStr,
        def->creationTime = tv.tv_sec;
    }

+    memorySnapshot = virXPathString("string(./memory/@snapshot)", ctxt);
+    memoryFile = virXPathString("string(./memory/@file)", ctxt);
+    if (memorySnapshot) {
+        def->memory = virDomainSnapshotLocationTypeFromString(memorySnapshot);
+        if (def->memory <= 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("unknown memory snapshot setting '%s'"),
+                           memorySnapshot);
+            goto cleanup;
+        }
+        if (memoryFile &&
+            def->memory != VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("memory filename '%s' requires external snapshot"),
+                           memoryFile);
+            goto cleanup;
+        }
+    } else if (memoryFile) {
+        def->memory = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL;
+    } else if (flags & VIR_DOMAIN_SNAPSHOT_PARSE_REDEFINE) {
+        def->memory = (offline ?
+                       VIR_DOMAIN_SNAPSHOT_LOCATION_NONE :
+                       VIR_DOMAIN_SNAPSHOT_LOCATION_INTERNAL);
+    }
+    if (offline && def->memory &&
+        def->memory != VIR_DOMAIN_SNAPSHOT_LOCATION_NONE) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("memory state cannot be saved with offline snapshot"));
+        goto cleanup;
+    }
+    def->file = memoryFile;
+    memoryFile = NULL;
+
    if ((i = virXPathNodeSet("./disks/*", ctxt, &nodes)) < 0)
        goto cleanup;
-    if (flags & VIR_DOMAIN_SNAPSHOT_PARSE_DISKS ||
-        (flags & VIR_DOMAIN_SNAPSHOT_PARSE_REDEFINE &&
-         def->state == VIR_DOMAIN_DISK_SNAPSHOT)) {
+    if (flags & VIR_DOMAIN_SNAPSHOT_PARSE_DISKS) {
        def->ndisks = i;
        if (def->ndisks && VIR_ALLOC_N(def->disks, def->ndisks) < 0) {
            virReportOOMError();
@ -306,6 +343,8 @@ cleanup:
    VIR_FREE(creation);
    VIR_FREE(state);
    VIR_FREE(nodes);
+    VIR_FREE(memorySnapshot);
+    VIR_FREE(memoryFile);
    xmlXPathFreeContext(ctxt);
    if (ret == NULL)
        virDomainSnapshotDefFree(def);
@ -527,8 +566,13 @@ char *virDomainSnapshotDefFormat(const char *domain_uuid,
    }
    virBufferAsprintf(&buf, "  <creationTime>%lld</creationTime>\n",
                      def->creationTime);
-    /* For now, only output <disks> on disk-snapshot */
-    if (def->state == VIR_DOMAIN_DISK_SNAPSHOT) {
+    if (def->memory) {
+        virBufferAsprintf(&buf, "  <memory snapshot='%s'",
+                          virDomainSnapshotLocationTypeToString(def->memory));
+        virBufferEscapeString(&buf, " file='%s'", def->file);
+        virBufferAddLit(&buf, "/>\n");
+    }
+    if (def->ndisks) {
        virBufferAddLit(&buf, "  <disks>\n");
        for (i = 0; i < def->ndisks; i++) {
            virDomainSnapshotDiskDefPtr disk = &def->disks[i];
--- a/src/conf/snapshot_conf.h
+++ b/src/conf/snapshot_conf.h
@ -66,6 +66,9 @@ struct _virDomainSnapshotDef {
    long long creationTime; /* in seconds */
    int state; /* enum virDomainSnapshotState */

+    int memory; /* enum virDomainMemorySnapshot */
+    char *file; /* memory state file when snapshot is external */
+
    size_t ndisks; /* should not exceed dom->ndisks */
    virDomainSnapshotDiskDef *disks;

@ -93,6 +96,7 @@ typedef enum {
    VIR_DOMAIN_SNAPSHOT_PARSE_REDEFINE = 1 << 0,
    VIR_DOMAIN_SNAPSHOT_PARSE_DISKS    = 1 << 1,
    VIR_DOMAIN_SNAPSHOT_PARSE_INTERNAL = 1 << 2,
+    VIR_DOMAIN_SNAPSHOT_PARSE_OFFLINE  = 1 << 3,
 } virDomainSnapshotParseFlags;

 virDomainSnapshotDefPtr virDomainSnapshotDefParseString(const char *xmlStr,
--- a/tests/domainsnapshotxml2xmlin/external_vm.xml
+++ b/tests/domainsnapshotxml2xmlin/external_vm.xml
@ -0,0 +1,10 @@
+<domainsnapshot>
+  <name>my snap name</name>
+  <description>!@#$%^</description>
+  <state>running</state>
+  <memory snapshot='external' file='/dev/HostVG/GuestMemory'/>
+  <parent>
+    <name>earlier_snap</name>
+  </parent>
+  <creationTime>1272917631</creationTime>
+</domainsnapshot>
--- a/tests/domainsnapshotxml2xmlin/noparent.xml
+++ b/tests/domainsnapshotxml2xmlin/noparent.xml
@ -0,0 +1,9 @@
+<domainsnapshot>
+  <name>my snap name</name>
+  <description>!@#$%^</description>
+  <state>running</state>
+  <creationTime>1272917631</creationTime>
+  <domain>
+    <uuid>9d37b878-a7cc-9f9a-b78f-49b3abad25a8</uuid>
+  </domain>
+</domainsnapshot>
--- a/tests/domainsnapshotxml2xmlout/all_parameters.xml
+++ b/tests/domainsnapshotxml2xmlout/all_parameters.xml
@ -6,6 +6,7 @@
    <name>earlier_snap</name>
  </parent>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='internal'/>
  <domain>
    <uuid>9d37b878-a7cc-9f9a-b78f-49b3abad25a8</uuid>
  </domain>
--- a/tests/domainsnapshotxml2xmlout/disk_snapshot.xml
+++ b/tests/domainsnapshotxml2xmlout/disk_snapshot.xml
@ -6,6 +6,7 @@
    <name>earlier_snap</name>
  </parent>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='no'/>
  <disks>
    <disk name='hda' snapshot='no'/>
    <disk name='hdb' snapshot='no'/>
--- a/tests/domainsnapshotxml2xmlout/external_vm.xml
+++ b/tests/domainsnapshotxml2xmlout/external_vm.xml
@ -0,0 +1,43 @@
+<domainsnapshot>
+  <name>my snap name</name>
+  <description>!@#$%^</description>
+  <state>running</state>
+  <parent>
+    <name>earlier_snap</name>
+  </parent>
+  <creationTime>1272917631</creationTime>
+  <memory snapshot='external' file='/dev/HostVG/GuestMemory'/>
+  <disks>
+    <disk name='hda' snapshot='no'/>
+  </disks>
+  <domain type='qemu'>
+    <name>QEMUGuest1</name>
+    <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+    <metadata>
+      <app1:foo xmlns:app1="http://foo.org/">fooish</app1:foo>
+      <app2:bar xmlns:app2="http://bar.com/" maman="baz">barish</app2:bar>
+    </metadata>
+    <memory unit='KiB'>219100</memory>
+    <currentMemory unit='KiB'>219100</currentMemory>
+    <vcpu placement='static' cpuset='1-4,8-20,525'>1</vcpu>
+    <os>
+      <type arch='i686' machine='pc'>hvm</type>
+      <boot dev='hd'/>
+    </os>
+    <clock offset='utc'/>
+    <on_poweroff>destroy</on_poweroff>
+    <on_reboot>restart</on_reboot>
+    <on_crash>destroy</on_crash>
+    <devices>
+      <emulator>/usr/bin/qemu</emulator>
+      <disk type='block' device='disk' snapshot='no'>
+        <source dev='/dev/HostVG/QEMUGuest1'/>
+        <target dev='hda' bus='ide'/>
+        <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+      </disk>
+      <controller type='usb' index='0'/>
+      <controller type='ide' index='0'/>
+      <memballoon model='virtio'/>
+    </devices>
+  </domain>
+</domainsnapshot>
--- a/tests/domainsnapshotxml2xmlout/full_domain.xml
+++ b/tests/domainsnapshotxml2xmlout/full_domain.xml
@ -6,6 +6,7 @@
    <name>earlier_snap</name>
  </parent>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='internal'/>
  <domain type='qemu'>
    <name>QEMUGuest1</name>
    <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
--- a/tests/domainsnapshotxml2xmlout/metadata.xml
+++ b/tests/domainsnapshotxml2xmlout/metadata.xml
@ -6,6 +6,7 @@
    <name>earlier_snap</name>
  </parent>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='internal'/>
  <domain type='qemu'>
    <name>QEMUGuest1</name>
    <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
--- a/tests/domainsnapshotxml2xmlout/noparent.xml
+++ b/tests/domainsnapshotxml2xmlout/noparent.xml
@ -3,6 +3,7 @@
  <description>!@#$%^</description>
  <state>running</state>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='internal'/>
  <domain>
    <uuid>9d37b878-a7cc-9f9a-b78f-49b3abad25a8</uuid>
  </domain>
--- a/tests/domainsnapshotxml2xmlout/noparent_nodescription.xml
+++ b/tests/domainsnapshotxml2xmlout/noparent_nodescription.xml
@ -3,5 +3,6 @@
  <description>!@#$%^</description>
  <state>running</state>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='internal'/>
  <active>1</active>
 </domainsnapshot>
--- a/tests/domainsnapshotxml2xmlout/noparent_nodescription_noactive.xml
+++ b/tests/domainsnapshotxml2xmlout/noparent_nodescription_noactive.xml
@ -3,4 +3,5 @@
  <description>!@#$%^</description>
  <state>running</state>
  <creationTime>1272917631</creationTime>
+  <memory snapshot='no'/>
 </domainsnapshot>
--- a/tests/domainsnapshotxml2xmltest.c
+++ b/tests/domainsnapshotxml2xmltest.c
@ -110,6 +110,7 @@ mymain(void)
    DO_TEST("noparent_nodescription", NULL, 1);
    DO_TEST("noparent", "9d37b878-a7cc-9f9a-b78f-49b3abad25a8", 0);
    DO_TEST("metadata", "c7a5fdbd-edaf-9455-926a-d65c16db1809", 0);
+    DO_TEST("external_vm", "c7a5fdbd-edaf-9455-926a-d65c16db1809", 0);

    virCapabilitiesFree(driver.caps);