diff --git a/migrear b/migrear
index f5d79167a48009d61ab203c645ebfe37fb4d4b75..865975c64737a41e8768e24915b5d768136fbfa1 100644
--- a/migrear
+++ b/migrear
@@ -3,12 +3,21 @@
 import argparse
 import os
 import sys
+import time
+import random
 import platform
 import re
 
 import subprocess
 
 
+HASH_RETRY = 5
+
+class HashCollisionException(Exception):
+    def __init__(self, message="backup fails for hash collides, try changing your hostname."):
+        super().__init__(message)
+
+
 class MethodNotSupportException(Exception):
     def __init__(self, method, message="unsupport method '{}', available choices {}."):
         self.methods_supported = ["nfs", "local"]
@@ -27,6 +36,10 @@ class NotRootPathException(Exception):
         self.message = message.format(path)
         super().__init__(self.message)
 
+def p64(n: int) -> str:
+    table = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_"
+    s = bin(n)[2:][::-1]
+    return "".join([table[int(s[i : i + 6][::-1], 2)] for i in range(0, len(s), 6)][::-1])
 
 def check_output(cmd):
     output = subprocess.check_output(cmd, shell=True)
@@ -63,7 +76,22 @@ def recover_preset():
     raise TypeError("Can not found backup grubby entry with title=MigReaR-xxxx")
 
 
-def backup(method, initramfs_path, initramfs_url, layout_path, layout_url, excludes):
+def backup(method, initramfs_path, initramfs_url, layout_path, layout_url, host_ip, excludes, hash=None):
+    if hash is None:
+        tmp_mountponit = "/tmp/mnt"
+        if not os.path.exists(tmp_mountponit):
+            os.makedirs(tmp_mountponit)
+        check_call("mount -v -t nfs -o rw,noatime %s:%s %s" % (host_ip, layout_path, tmp_mountponit))
+        for _ in range(HASH_RETRY):
+            hash = p64(int(time.time() * 10 ** 7)) + p64(random.randint(0, 1<<12)).rjust(2, '0')[-12:]
+            if not os.path.exists("%s/%s-%s" % (tmp_mountponit, platform.node(), hash)):
+                os.makedirs("%s/%s-%s" % (tmp_mountponit, platform.node(), hash))
+                check_call("umount " + tmp_mountponit)
+                break
+        else:
+            check_call("umount " + tmp_mountponit)
+            raise HashCollisionException()
+
     local_cfg = """
 OUTPUT=RAMDISK
 OUTPUT_URL=%s
@@ -71,7 +99,9 @@ BACKUP=NETFS
 BACKUP_URL=%s
 BACKUP_PROG_EXCLUDE=("\$\{BACKUP_PROG_EXCLUDE[@]\}" '/media' '/var/tmp' '/var/crash' %s '/tmp/*')
 NETFS_KEEP_OLD_BACKUP_COPY=
-""" % (initramfs_url, layout_url, " ".join(excludes))
+NETFS_PREFIX="$HOSTNAME-%s"
+RAMDISK_SUFFIX="%s"
+""" % (initramfs_url, layout_url, " ".join(excludes), hash, hash)
 
     with open("/etc/rear/local.conf", "w") as f:
         f.write(local_cfg)
@@ -91,10 +121,9 @@ NETFS_KEEP_OLD_BACKUP_COPY=
 
     # grub
     vmlinuz = check_output("ls /boot/vmlinuz-$(uname -r)").strip()
-    vmlinux_ver = vmlinuz.rpartition('/')[-1]
 
-    initramfs_file_path = check_output("find %s -name 'initramfs-%s.img'" % (initramfs_path, platform.node()))
-    command = "grubby --add-kernel %s --initrd %s --title MigReaR-%s " % (vmlinuz, initramfs_file_path, vmlinux_ver)
+    initramfs_file_path = check_output("find %s -name 'initramfs-%s.img'" % (initramfs_path, hash))
+    command = "grubby --add-kernel %s --initrd %s --title MigReaR-%s " % (vmlinuz, initramfs_file_path, hash)
     if method == "nfs":
         args = " --args='ro console=tty0 console=ttyS0,115200n8 console=ttyS0 unattended'"
     elif method == "local":
@@ -112,6 +141,7 @@ def parse_args():
     parser.add_argument('--path', default='/storage', help="where root layout would be kept, /storage by default.")
     parser.add_argument('--boot', default=None, help="where initramfs would be kept, same with --path if not given.")
     parser.add_argument('--recover_preset', default=None, help="set recover")
+    parser.add_argument('--hash', default=None, help="specific backup hash, if not given, the program will generate one to determine backup files among several machines.")
 
     args = parser.parse_args()
 
@@ -147,4 +177,4 @@ if __name__ == "__main__":
     if args.recover_preset:
         recover_preset()
     else:
-        backup(args.method, args.boot, args.initramfs_path, args.path, args.layout_path, args.excludes)
+        backup(args.method, args.boot, args.initramfs_path, args.path, args.layout_path, args.url, args.excludes, args.hash)