~kim0/serverguide/serverguide-review-ch19

<div class="breadcrumbs"><a href="https://help.ubuntu.com/">Ubuntu Documentation</a> > <a href="https://help.ubuntu.com/11.04">Ubuntu 11.04</a> > <span class="breadcrumb-link"><a href="index.html">Ubuntu Server Guide</a></span> > <span class="breadcrumb-link"><a href="backups.html">Backups</a></span> > <span class="breadcrumb-node">Archive Rotation</span></div>

<div>

<h2 class="title" style="clear: both"><a id="backups-shellscripts-rotation"></a>Archive Rotation</h2>

</div>

<p>

The shell script in section <a class="xref" href="backup-shellscripts.html" title="Shell Scripts">the section called “Shell Scripts”</a> only allows for seven different archives. For

a server whose data doesn't change often this may be enough. If the server has a large amount of data a more

robust rotation scheme should be used.

</p>

<div>

<h3 class="title"><a id="backups-nfs-rotation"></a>Rotating NFS Archives</h3>

</div>

<p>

In this section the shell script will be slightly modified to implement a grandfather-father-son rotation scheme

(monthly-weekly-daily):

</p>

<p>

The rotation will do a <span class="emphasis"><em>daily</em></span> backup Sunday through Friday.

</p>

</li>

<p>

On Saturday a <span class="emphasis"><em>weekly</em></span> backup is done giving you four weekly backups a month.

</p>

</li>

100

<p>

101

The <span class="emphasis"><em>monthly</em></span> backup is done on the first of the month rotating two monthly backups based

102

on if the month is odd or even.

103

</p>

104

</li>

105

</ul>

106

</div>

107

<p>

108

Here is the new script:

109

</p>

110

111

#!/bin/bash

112

####################################

113

114

# Backup to NFS mount script with

115

# grandfather-father-son rotation.

116

117

####################################

118

119

# What to backup.

120

backup_files="/home /var/spool/mail /etc /root /boot /opt"

121

122

# Where to backup to.

123

dest="/mnt/backup"

124

125

# Setup variables for the archive filename.

126

day=$(date +%A)

127

hostname=$(hostname -s)

128

129

# Find which week of the month 1-4 it is.

130

day_num=$(date +%d)

131

if (( $day_num <= 7 )); then

132

week_file="$hostname-week1.tgz"

133

elif (( $day_num > 7 && $day_num <= 14 )); then

134

week_file="$hostname-week2.tgz"

135

elif (( $day_num > 14 && $day_num <= 21 )); then

136

week_file="$hostname-week3.tgz"

137

elif (( $day_num > 21 && $day_num < 32 )); then

138

week_file="$hostname-week4.tgz"

139

140

141

# Find if the Month is odd or even.

142

month_num=$(date +%m)

143

month=$(expr $month_num % 2)

144

if [ $month -eq 0 ]; then

145

month_file="$hostname-month2.tgz"

146

else

147

month_file="$hostname-month1.tgz"

148

149

150

# Create archive filename.

151

if [ $day_num == 1 ]; then

152

archive_file=$month_file

153

elif [ $day != "Saturday" ]; then

154

archive_file="$hostname-$day.tgz"

155

else

156

archive_file=$week_file

157

158

159

# Print start status message.

160

echo "Backing up $backup_files to $dest/$archive_file"

161

date

162

echo

163

164

# Backup the files using tar.

165

tar czf $dest/$archive_file $backup_files

166

167

# Print end status message.

168

echo

169

echo "Backup finished"

170

date

171

172

# Long listing of files in $dest to check file sizes.

173

ls -lh $dest/

174

</pre>

175

<p>

176

The script can be executed using the same methods as in <a class="xref" href="backup-shellscripts.html#backup-executing-shellscript" title="Executing the Script">the section called “Executing the Script”</a>.

177

</p>

178

<p>

179

It is good practice to take backup media off site in case of a disaster. In the shell script example the backup

180

media is another server providing an NFS share. In all likelihood taking the NFS server to another location would not

181

be practical.

182

Depending upon connection speeds it may be an option to copy the archive file over a WAN link to a server in another location.

183

</p>

184

<p>

185

Another option is to copy the archive file to an external hard drive which can then be taken off site.

186

Since the price of external hard drives continue to decrease it may be cost-effective to use two drives for each archive level.

187

This would allow you to have one external drive attached to the backup server and one in another location.

188

</p>

189

</div>

190

191

192

<div>

193

<div>

194

<h3 class="title"><a id="backup-shellscript-tapedrive"></a>Tape Drives</h3>

195

</div>

196

</div>

197

</div>

198

<p>

199

A tape drive attached to the server can be used instead of a NFS share. Using a tape drive simplifies archive rotation, and

200

taking the media off site as well.

201

</p>

202

<p>

203

When using a tape drive the filename portions of the script aren't needed because the date is sent directly to the tape device.

204

Some commands to manipulate the tape are needed. This is accomplished using <span class="application"><strong>mt</strong></span>, a magnetic tape

205

control utility part of the <span class="application"><strong>cpio</strong></span> package.

206

</p>

207

<p>

208

Here is the shell script modified to use a tape drive:

209

</p>

210

211

#!/bin/bash

212

####################################

213

214

# Backup to tape drive script.

215

216

####################################

217

218

# What to backup.

219

backup_files="/home /var/spool/mail /etc /root /boot /opt"

220

221

# Where to backup to.

222

dest="/dev/st0"

223

224

# Print start status message.

225

echo "Backing up $backup_files to $dest"

226

date

227

echo

228

229

# Make sure the tape is rewound.

230

mt -f $dest rewind

231

232

# Backup the files using tar.

233

tar czf $dest $backup_files

234

235

# Rewind and eject the tape.

236

mt -f $dest rewoffl

237

238

# Print end status message.

239

echo

240

echo "Backup finished"

241

date

242

</pre>

243

244

245

<tr>

246

247

248

</td>

249

250

</tr>

251

<tr>

252

253

<p>

254

The default device name for a SCSI tape drive is <code class="filename">/dev/st0</code>. Use the appropriate device path for your

255

system.

256

</p>

257

</td>

258

</tr>

259

</table>

260

</div>

261

<p>

262

Restoring from a tape drive is basically the same as restoring from a file. Simply rewind the tape and use the device path

263

instead of a file path. For example to restore the <code class="filename">/etc/hosts</code> file to <code class="filename">/tmp/etc/hosts</code>:

264

</p>

265

266

<span class="command"><strong>mt -f /dev/st0 rewind</strong></span>

267

<span class="command"><strong>tar -xzf /dev/st0 -C /tmp etc/hosts</strong></span>

268

</pre>

269

</div>

270

</div>

271

</div>

272

273

<hr />

274

275

<tr>

276

277

278

279

280

</a>

281

</td>

282

283

</tr>

284

<tr>

285

<td width="40%" align="left" valign="top">Shell Scripts </td>

286

287

288

289

</a>

290

</td>

291

<td width="40%" align="right" valign="top"> Bacula</td>

292

</tr>

293

</table>

294

</div>

295

<hr />

296

297

298

<p>The material in this document is available under a free license, see <a href="/legal.html">Legal</a> for details<br />

299

For information on contributing see the <a href="https://wiki.ubuntu.com/DocumentationTeam">Ubuntu Documentation Team wiki page</a>. To report a problem, visit the <a href="https://bugs.launchpad.net/ubuntu/+source/ubuntu-docs">bug page for Ubuntu Documentation</a></p>

300

</div>

301

</div>

302

303

304

</div>

305

</div>

306

</div>

307

</div>

308

</body>

309

</html>

Older »