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Re: [libvirt] (Resend) Live Migration with non-shared storage for kvm



On 04/22/2010 11:06 AM, Kenneth Nagin wrote:
> Support for live migration between hosts that do not share storage was
> added to qemu-kvm release 0.12.1.
> It supports two flags:
> -b migration without shared storage with full disk copy
> -i migration without shared storage with incremental copy (same base image
> shared between source and destination).
> 
> In order to support kvm's live migration with non-shared storage I added
> two migration flags that user can invoke:
> 
>     VIR_MIGRATE_NON_SHARED_DISK   = (1 << 6), /* migration with non-shared
> storage with full disk copy */
>     VIR_MIGRATE_NON_SHARED_INC    = (1 << 7), /* migration with non-shared
> storage with incremental copy */
>                                               /* (same base image shared
> between source and destination) */
> Likewise I add complementary flags to virsh migrate: non_shared_disk and
> non_shared_inc
> 
> As Daniel B. suggested I also added internal flags to be passed in the
> "background" parameter to the qemu monitor:
> typedef enum {
>   QEMU_MONITOR_MIGRATE_BACKGROUND         = 1 << 0,
>   QEMU_MONITOR_MIGRATE_NON_SHARED_DISK  = 1 << 1, /* migration with
> non-shared storage with full disk copy */
>   QEMU_MONITOR_MIGRATE_NON_SHARED_INC   = 1 << 2, /* migration with
> non-shared storage with incremental copy */
>   QEMU_MONITOR_MIGRATION_FLAGS_LAST
> };
> 
> I updated qemu_driver.c's doNativeMigrate and doTunnelMigrate to map the
> external flags to the internal flags.
> I updated qemu_monitor_text's qemuMonitorTextMigrate to map the internal
> flags to the qemu monitor's command line flags.
> 
> Also, qemudDomainSave ends up calling qemuMonitorTextMigrate, but it didn't
> support the external flags so I assumed that it was not relevant.
> 
> I tested the live migration without shared storage (both flags) for native
> and p2p with and without tunnelling.  I also verified that the fix doesn't
> affect normal migration with shared storage.
> 
> Here is the diff patch file from the current git:
> 
> (See attached file: libvirt_migration_ns_100422.patch)
> 
> 
> -- Kenneth Nagin
> 

Of course, I tell you to resend then forget to review. Sorry :(

Applying the patch (to last weeks checkout), there are some compiler warnings:
make sure you configure with --enable-compiler-warnings=error. 'make
syntax-check' also fails, so please address these.

Also, changes are probably needed to qemu_monitor_json.c to enable this
feature for future qemu releases. Probably a simple change, but I don't know
what it should be. Maybe Danpb can chime in here.

Finding a way to post the patch in-line will also probably get better
attention: just pasting it into the mail client will probably mangle the
patch, I'd recommend git send-email.

For the virsh changes, I wouldn't use underscores in cli flag names. Maybe
change this to 'copy-storage' and 'increment-storage'. Not too fond of the
latter, maybe others have ideas.

Other than that, the code generally looks like (except for the compiler and
syntax-check warnings).

- Cole

(Here's the patch inline for the benefit of other reviewers)

> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index 4addc62..28fabd9 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -411,6 +411,10 @@ typedef enum {
>      VIR_MIGRATE_PERSIST_DEST      = (1 << 3), /* persist the VM on the destination */
>      VIR_MIGRATE_UNDEFINE_SOURCE   = (1 << 4), /* undefine the VM on the source */
>      VIR_MIGRATE_PAUSED            = (1 << 5), /* pause on remote side */
> +    VIR_MIGRATE_NON_SHARED_DISK   = (1 << 6), /* migration with non-shared storage with full disk copy */
> +    VIR_MIGRATE_NON_SHARED_INC    = (1 << 7), /* migration with non-shared storage with incremental copy */
> +                                              /* (same base image shared between source and destination) */
> +
>  } virDomainMigrateFlags;
>  
>  /* Domain migration. */
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 5f4adfd..521638c 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4871,7 +4871,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
>      if (header.compressed == QEMUD_SAVE_FORMAT_RAW) {
>          const char *args[] = { "cat", NULL };
>          qemuDomainObjEnterMonitorWithDriver(driver, vm);
> -        rc = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
> +        rc = qemuMonitorMigrateToCommand(priv->mon, QEMU_MONITOR_MIGRATE_BACKGROUND, args, path);
>          qemuDomainObjExitMonitorWithDriver(driver, vm);
>      } else {
>          const char *prog = qemudSaveCompressionTypeToString(header.compressed);
> @@ -4881,7 +4881,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
>              NULL
>          };
>          qemuDomainObjEnterMonitorWithDriver(driver, vm);
> -        rc = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
> +        rc = qemuMonitorMigrateToCommand(priv->mon, QEMU_MONITOR_MIGRATE_BACKGROUND, args, path);
>          qemuDomainObjExitMonitorWithDriver(driver, vm);
>      }
>  
> @@ -5173,7 +5173,7 @@ static int qemudDomainCoreDump(virDomainPtr dom,
>      }
>  
>      qemuDomainObjEnterMonitor(vm);
> -    ret = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
> +    ret = qemuMonitorMigrateToCommand(priv->mon, QEMU_MONITOR_MIGRATE_BACKGROUND, args, path);
>      qemuDomainObjExitMonitor(vm);
>  
>      if (ret < 0)
> @@ -9650,13 +9650,14 @@ cleanup:
>  static int doNativeMigrate(struct qemud_driver *driver,
>                             virDomainObjPtr vm,
>                             const char *uri,
> -                           unsigned long flags ATTRIBUTE_UNUSED,
> +                           unsigned long flags ,
>                             const char *dname ATTRIBUTE_UNUSED,
>                             unsigned long resource)
>  {
>      int ret = -1;
>      xmlURIPtr uribits = NULL;
>      qemuDomainObjPrivatePtr priv = vm->privateData;
> +    int background_flags = 0;
>  
>      /* Issue the migrate command. */
>      if (STRPREFIX(uri, "tcp:") && !STRPREFIX(uri, "tcp://")) {
> @@ -9684,7 +9685,13 @@ static int doNativeMigrate(struct qemud_driver *driver,
>          goto cleanup;
>      }
>  
> -    if (qemuMonitorMigrateToHost(priv->mon, 1, uribits->server, uribits->port) < 0) {
> +    if (flags & VIR_MIGRATE_NON_SHARED_DISK)
> +    	background_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_DISK;
> +
> +    if (flags & VIR_MIGRATE_NON_SHARED_INC)
> +    	background_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_INC;
> +
> +    if (qemuMonitorMigrateToHost(priv->mon, background_flags, uribits->server, uribits->port) < 0) {
>          qemuDomainObjExitMonitorWithDriver(driver, vm);
>          goto cleanup;
>      }
> @@ -9769,7 +9776,7 @@ static int doTunnelMigrate(virDomainPtr dom,
>      unsigned long long qemuCmdFlags;
>      int status;
>      unsigned long long transferred, remaining, total;
> -
> +    int background_flags = QEMU_MONITOR_MIGRATE_BACKGROUND;
>      /*
>       * The order of operations is important here to avoid touching
>       * the source VM until we are very sure we can successfully
> @@ -9854,11 +9861,16 @@ static int doTunnelMigrate(virDomainPtr dom,
>  
>      /*   3. start migration on source */
>      qemuDomainObjEnterMonitorWithDriver(driver, vm);
> -    if (qemuCmdFlags & QEMUD_CMD_FLAG_MIGRATE_QEMU_UNIX)
> -        internalret = qemuMonitorMigrateToUnix(priv->mon, 1, unixfile);
> +    if (flags & VIR_MIGRATE_NON_SHARED_DISK)
> +    	background_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_DISK;
> +    if (flags & VIR_MIGRATE_NON_SHARED_INC)
> +    	background_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_INC;
> +    if (qemuCmdFlags & QEMUD_CMD_FLAG_MIGRATE_QEMU_UNIX){
> +        internalret = qemuMonitorMigrateToUnix(priv->mon, background_flags, unixfile);
> +    }
>      else if (qemuCmdFlags & QEMUD_CMD_FLAG_MIGRATE_QEMU_EXEC) {
>          const char *args[] = { "nc", "-U", unixfile, NULL };
> -        internalret = qemuMonitorMigrateToCommand(priv->mon, 1, args, "/dev/null");
> +        internalret = qemuMonitorMigrateToCommand(priv->mon, background_flags, args, "/dev/null");
>      } else {
>          internalret = -1;
>      }
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index 251233a..40a21f5 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -239,6 +239,13 @@ int qemuMonitorGetMigrationStatus(qemuMonitorPtr mon,
>                                    unsigned long long *remaining,
>                                    unsigned long long *total);
>  
> +typedef enum {
> +  QEMU_MONITOR_MIGRATE_BACKGROUND 		= 1 << 0,
> +  QEMU_MONITOR_MIGRATE_NON_SHARED_DISK  = 1 << 1, /* migration with non-shared storage with full disk copy */
> +  QEMU_MONITOR_MIGRATE_NON_SHARED_INC   = 1 << 2, /* migration with non-shared storage with incremental copy */
> +  QEMU_MONITOR_MIGRATION_FLAGS_LAST
> +};
> +
>  int qemuMonitorMigrateToHost(qemuMonitorPtr mon,
>                               int background,
>                               const char *hostname,
> diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c
> index 6ad07b1..136ac12 100644
> --- a/src/qemu/qemu_monitor_text.c
> +++ b/src/qemu/qemu_monitor_text.c
> @@ -1132,18 +1132,19 @@ static int qemuMonitorTextMigrate(qemuMonitorPtr mon,
>      char *info = NULL;
>      int ret = -1;
>      char *safedest = qemuMonitorEscapeArg(dest);
> -    const char *extra;
> +    //const char *extra;
> +    const char extra[25] = " ";
>  
>      if (!safedest) {
>          virReportOOMError();
>          return -1;
>      }
> -
> -    if (background)
> -        extra = "-d ";
> -    else
> -        extra = " ";
> -
> +    if (background & QEMU_MONITOR_MIGRATE_BACKGROUND)
> +    	strcat(extra," -d");
> +    if (background & QEMU_MONITOR_MIGRATE_NON_SHARED_DISK)
> +        strcat(extra," -b");
> +    if (background & QEMU_MONITOR_MIGRATE_NON_SHARED_INC)
> +        strcat(extra," -i");
>      if (virAsprintf(&cmd, "migrate %s\"%s\"", extra, safedest) < 0) {
>          virReportOOMError();
>          goto cleanup;
> diff --git a/tools/virsh.c b/tools/virsh.c
> index b2a1538..bd8719e 100644
> --- a/tools/virsh.c
> +++ b/tools/virsh.c
> @@ -2804,6 +2804,8 @@ static const vshCmdOptDef opts_migrate[] = {
>      {"persistent", VSH_OT_BOOL, 0, N_("persist VM on destination")},
>      {"undefinesource", VSH_OT_BOOL, 0, N_("undefine VM on source")},
>      {"suspend", VSH_OT_BOOL, 0, N_("do not restart the domain on the destination host")},
> +    {"non_shared_disk", VSH_OT_BOOL, 0, N_("migration with non-shared storage with full disk copy")},
> +    {"non_shared_inc", VSH_OT_BOOL, 0, N_("migration with non-shared storage with incremental copy (same base image shared between source and destination)")},
>      {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name, id or uuid")},
>      {"desturi", VSH_OT_DATA, VSH_OFLAG_REQ, N_("connection URI of the destination host")},
>      {"migrateuri", VSH_OT_DATA, 0, N_("migration URI, usually can be omitted")},



> @@ -2851,6 +2853,12 @@ cmdMigrate (vshControl *ctl, const vshCmd *cmd)
>      if (vshCommandOptBool (cmd, "suspend"))
>          flags |= VIR_MIGRATE_PAUSED;
>  
> +    if (vshCommandOptBool (cmd, "non_shared_disk"))
> +        flags |= VIR_MIGRATE_NON_SHARED_DISK;
> +
> +    if (vshCommandOptBool (cmd, "non_shared_inc"))
> +        flags |= VIR_MIGRATE_NON_SHARED_INC;
> +
>      if ((flags & VIR_MIGRATE_PEER2PEER) ||
>          vshCommandOptBool (cmd, "direct")) {
>          /* For peer2peer migration or direct migration we only expect one URI



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