Hibernation: Add check for disk space requirement

1. Hibernation requires free disk space proportional to
RAM of the machine. LISA currently does not support
os disk size as a requirement.
2. Azure does not support Hibernation for VM with
memory larger than 256 GB

Author: adityagesh

lisa/microsoft/testsuites/power/common.py

@@ -15,6 +15,7 @@
     Df,
     Dmesg,
     Fio,
+    Free,
     HibernationSetup,
     Hwclock,
     Iperf3,
@@ -49,6 +50,60 @@ def is_distro_supported(node: Node) -> None:
         )
 
 
+def check_hibernation_disk_requirements(node: Node) -> None:
+    """
+    Check if the VM has sufficient disk space for hibernation.
+    Hibernation requires disk space based on RAM size using the formula:
+    - 2 × RAM if RAM ≤ 8 GB
+    - 1.5 × RAM if 8 < RAM ≤ 64 GB
+    - RAM if 64 < RAM ≤ 256 GB
+    - Not supported if RAM > 256 GB
+    """
+    free_tool = node.tools[Free]
+    df_tool = node.tools[Df]
+
+    # Get total memory in KB
+    total_memory_kb = free_tool._get_field_bytes_kib("Mem", "total")
+    total_memory_gb = total_memory_kb / (1024 * 1024)  # Convert KB to GB
+
+    # Skip hibernation check for VMs with > 256 GB RAM
+    if total_memory_gb > 256:
+        raise SkippedException(
+            f"Hibernation is not supported for VMs with RAM > 256 GB. "
+            f"Current RAM: {total_memory_gb:.2f} GB"
+        )
+
+    # Calculate required swap space based on RAM size
+    if total_memory_gb <= 8:
+        required_space_gb = 2 * total_memory_gb
+        formula = "2*RAM"
+    elif total_memory_gb <= 64:
+        required_space_gb = 1.5 * total_memory_gb
+        formula = "1.5*RAM"
+    else:
+        required_space_gb = total_memory_gb
+        formula = "RAM"
+
+    # Add 20% buffer for filesystem overhead, defragmentation, and safety margin
+    required_space_with_buffer = required_space_gb * 1.2
+
+    root_partition = df_tool.get_partition_by_mountpoint("/", force_run=True)
+    assert root_partition is not None, "Unable to determine root partition disk space"
+
+    # available_blocks is in 1K blocks, convert to GB
+    available_space_gb = root_partition.available_blocks / 1024 / 1024
+
+    if available_space_gb < required_space_with_buffer:
+        raise LisaException(
+            f"Insufficient disk space for hibernation. "
+            f"Memory size: {total_memory_gb:.2f} GB, "
+            f"Available space: {available_space_gb:.2f} GB, "
+            f"Required space: {required_space_gb:.2f} GB ({formula}), "
+            f"Recommended (20% buffer): {required_space_with_buffer:.2f} GB. "
+            f"Please increase 'osdisk_size_in_gb'."
+        )
+
+
 def _prepare_hibernation_environment(node: Node) -> None:
     """
     Prepare the hibernation environment by handling OS-specific requirements.
@@ -167,6 +222,11 @@ def verify_hibernation_by_tool(
 
     hibernation_setup_tool = node.tools[HibernationSetup]
 
+    # Verify disk space again before hibernation setup to
+    # ensure sufficient space after any package installations
+    # or system changes
+    check_hibernation_disk_requirements(node)
+
     # Get initial counts before hibernation
     entry_before_hibernation = hibernation_setup_tool.check_entry()
     exit_before_hibernation = hibernation_setup_tool.check_exit()

lisa/microsoft/testsuites/power/power.py

@@ -7,6 +7,7 @@
 from assertpy import assert_that
 from func_timeout import func_timeout
 from microsoft.testsuites.power.common import (
+    check_hibernation_disk_requirements,
     cleanup_env,
     is_distro_supported,
     run_network_workload,
@@ -46,6 +47,8 @@ def before_case(self, log: Logger, **kwargs: Any) -> None:
         if isinstance(node.os, BSD) or isinstance(node.os, Windows):
             raise SkippedException(f"{node.os} is not supported.")
 
+        check_hibernation_disk_requirements(node)
+
     @TestCaseMetadata(
         description="""
             This case is to verify vm hibernation with synthetic network.