3 I have two 500 GB hard disks both with the Hammer file system. I want to create a master PFS in one hard disk and a slave PFS in the other disk. I want to mirror the data continuously from the master PFS to the slave PFS. This will help me avoid long 'fsck' and RAID parity rewrite times after an unclean shut down, and also will give me a setup somewhat like RAID 1.
5 #Creating the master PFS on Disk 1
7 The Hammer file systems on Disk 1 and Disk 2 are mounted in '/etc/fstab' according to the following.
9 /dev/ad4s1h /Backup1 hammer rw 2 2
10 /dev/ad6s1h /Backup2 hammer rw 2 2
12 Go to the Hammer file system on Disk 1. We will be creaing a master PFS called 'test' and will be mounting it using a null mount. If you don't have a directory called 'pfs' under the Hammer file system you should create it.
18 If you already have the pfs directory under the Hammer file system you can skip the above step and continue.
20 # hammer pfs-master /Backup1/pfs/test
21 Creating PFS #3 succeeded!
23 sync-beg-tid=0x0000000000000001
24 sync-end-tid=0x000000013f644ce0
25 shared-uuid=9043570e-b3d9-11de-9bef-011617202aa6
26 unique-uuid=9043574c-b3d9-11de-9bef-011617202aa6
30 snapshots dir for master defaults to <fs>/snapshots
33 Now the master PFS 'test' is created. Make a note of its 'shared-uuid' because we will need to use that to create the slave PFS for mirroring.
34 You can mount the PFS under the Hammer file system on Disk 1 by doing the following.
38 Now Edit '/etc/fstab' to contain the following line.
40 /Backup1/pfs/test /Backup1/test null rw 0 0
42 Now mount the PFS by doing.
46 /Backup1/pfs/@@-1:00003 on /Backup1/test (null, local)
48 #Creating the slave PFS on Disk 2.
50 Note that we must use the 'shared-uuid' of the master PFS to enable mirroring.
52 # hammer pfs-slave /Backup2/pfs/test shared-uuid=9043570e-b3d9-11de-9bef-011617202aa6
53 Creating PFS #3 succeeded!
55 sync-beg-tid=0x0000000000000001
56 sync-end-tid=0x0000000000000001
57 shared-uuid=9043570e-b3d9-11de-9bef-011617202aa6
58 unique-uuid=97d77f53-b3da-11de-9bef-011617202aa6
63 snapshots directory not set for slave
66 The slave PFS is not mounted but a symlink can be created in the root Hammer file system to point to it. This step is optional, the PFS can be read through its original magic symlink in /Backup2/pfs.
68 # ln -s /Backup2/pfs/test /Backup2/test
70 lrwxr-xr-x 1 root wheel 17 Oct 8 12:07 /Backup2/test -> /Backup2/pfs/test
72 #Copying contents from PFS on Disk 1 to PFS on Disk 2 to enable mirroring.
74 The slave PFS will be accessible only after the first 'mirror-copy' operation.
76 # touch /Backup1/test/test-file
81 We do the "sync" so that the file creation operation in flushed from the kernel memory. Mirroring works only on operations flushed from the kernel memory. The slave PFS will be accessible only after the first mirroring operation.
83 # hammer mirror-copy /Backup1/test /Backup2/pfs/test
84 histogram range 000000013f6425fd - 000000013f644d60
85 Mirror-read: Mirror from 0000000000000002 to 000000013f644d60
86 Mirror-read /Backup1/test succeeded
91 #Enabling continuous mirroring.
93 You can enable continuous mirroring by editing a few files.
94 One way to make sure the mirroring works continuously is to use the 'lockf' utility.
95 This is one way to do it.
97 # mkdir /root/adm && cd /root/adm
100 Now make two scripts 'hms' and 'hmc' with the following contents inside /root/adm
103 hammer mirror-stream /Backup1/test /Backup2/test &
106 hammer synctid /Backup1/test
107 hammer mirror-copy /Backup1/test /Backup2/test
109 Edit '/etc/rc.local' and add the following line.
111 (cd /root/adm; /usr/bin/lockf -k -t 0 .lockfile ./hms) &
113 Edit 'crontab' and add the following Lines.
115 #Check and restart mirroring if needed every 10 minutes
116 10 1 * * * (cd /root/adm; /usr/bin/lockf -k -t 0 .lockfile ./hms) &
118 Edit '/etc/rc.shutdown.local' and add the following lines.
120 pkill -f /usr/bin/lockf -k -t 0 .lockfile ./hms
121 pkill -f hammer mirror-stream /Backup1/test /Backup2/test
122 (cd /root/adm; /usr/bin/lockf -k -t 10 .lockfile ./hmc)