Linux System Administration Recipes A Problem-Solution Approach

More documents

Recommendations

Info

CHAPTER 2 ■ CENTRALIZING YOUR NETWORK: KERBEROS, LDAP, AND NFSdn: cn=jkemp,ou=auto.home,dc=example,dc=comobjectClass: automountcn: jkempautomountInformation: -fstype=nfs,rw server1:/export/home/jkempautomountMapName: auto_homeAuthenticate as the LDAP admin user (kinit ldapadm if you’re using Kerberos), and add theseentries to the database:ldapadd < automount.ldifYou should now be able to automount /home/jkemp from your client. Repeat this for your otherusers.2-15. Connecting Macs to a <strong>Linux</strong> NFS ServerIf you have Macs on your network that want to be able to connect to an NFS server, you will run into theproblem that <strong>Linux</strong> NFS expects clients to use a privileged network port (less than 1024); while Mac (andother OpenBSD-based systems) use a port above 1024 for NFS requests.There are two ways of solving this. The first is to add the insecure parameter to the /etc/exports fileon the server:/local 10.1.0.*rw,insecureIf you prefer and you have only one or two Macs, you could do this for only them in particular:/local 10.1.0.17/local 10.1.0.*rw,insecurerwThe other option is to fix it at the client end. This is probably neater but may cause you moreproblems with users, depending on your setup. You need to add -P to the command line (one of the userproblems here is that you can’t do this from the Finder).mount -P server:/local /mnt2-16. Improving NFS PerformanceIf you’re experiencing performance problems, you can look at /proc/net/rpc/nfsd for some diagnosticinformation. For example, the th line in that file indicates the number of seconds during which thethread usage was at the maximum allowable. If this is a large number, you may want to increase thenumber of NFS instances available (that is, the number of servers running). The standard default is 8,but more heavily used servers may benefit from having more. This is specified with the RPCNFSDCOUNTvalue, which is given in the init script (/etc/init.d/nfs-kernel-server on Debian/Ubuntu).60Download at WoweBook.Com
CHAPTER 2 ■ CENTRALIZING YOUR NETWORK: KERBEROS, LDAP, AND NFS■ Note If you’re using a system on which the file /etc/default/nfs-kernel-server exists (for example,Debian/Ubuntu), then you’ll also need to set the new RPCNFSDCOUNT value in this file.If you’re experiencing load or performance issues, you can also increase the memory queue limits.These are frequently low by default, especially on 2.4 kernels, and because the memory queue is sharedbetween all the server instances, it’s probably a good idea to increase the memory queue if you increasethe number of servers. The limits are set using proc. Use /proc/sys/net/core/rmem_default and/proc/sys/net/core/rmem_max for the read limits, and use /proc/sys/net/core/wmem_default and/proc/sys/net/core/wmem_max for the read limits. Reset them to 256k as follows:# echo 262144 > /proc/sys/net/core/rmem_default# echo 262144 > /proc/sys/net/core/rmem_max# echo 262144 > /proc/sys/net/core/wmem_default# echo 262144 > /proc/sys/net/core/wmem_maxThen restart the NFS server with /etc/init.d/nfs-kernel-server.■ Note There are some reports of problems generated in other systems if these values are left unchanged forlong periods of time. You can reset them after you’ve restarted the NFS server (using the same lines as shownpreviously, but substitute 65536 for 262144). However, bear in mind that in this case, the new values will bediscarded the next time you have to restart NFS. Perhaps better is to watch for problems and reset the values ifthey arise.nfsstat -s (on the server) and nfsstat -c (on the client) may also be helpful. These both show NFSstatistics. In particular, if badcalls is greater than zero, you may have network problems, and if writes isgreater than 10 percent, it may be worth looking into write caching to speed up operation.nfsstat -m from the client provides server information from the client’s point of view. The srttgives a smoothed round-trip time value. If this is greater than 50ms, the mount point is slow. cur givesthe timeout value. If cur > 80ms for lookups, cur > 150ms for reads, and/or cur > 250ms for writes, thenthe requests are taking too long.61Download at WoweBook.Com
Page 2:
Download at WoweBook.Com
Page 5 and 6:
Download at WoweBook.Comiii
Page 7 and 8:
Contents■About the Author .......
Page 9 and 10:
■ CONTENTS3-7. Writing a Nagios P
Page 11 and 12:
■ CONTENTS■Chapter 8: Using the
Page 13 and 14:
■ CONTENTSAbout the Author■Juli
Page 15 and 16:
■ CONTENTSAcknowledgmentsMany tha
Page 17 and 18:
■ CONTENTSIntroductionThis book i
Page 19 and 20:
■ INTRODUCTIONDownloading the Cod
Page 21 and 22:
C H A P T E R 1■ ■ ■Saving Yo
Page 23 and 24:
CHAPTER 1 ■ SAVING YOURSELF EFFOR
Page 25 and 26:
Page 27 and 28:
Page 29 and 30: CHAPTER 1 ■ SAVING YOURSELF EFFOR
Page 41 and 42: C H A P T E R 2■ ■ ■Centraliz
Page 43 and 44: CHAPTER 2 ■ CENTRALIZING YOUR NET
Page 79: CHAPTER 2 ■ CENTRALIZING YOUR NET
Page 83 and 84: C H A P T E R 3■ ■ ■Monitorin
Page 85 and 86: CHAPTER 3 ■ MONITORING AND UPDATI
Page 115 and 116: C H A P T E R 4■ ■ ■Taking Ba
Page 117 and 118: CHAPTER 4 ■ TAKING BACKUPS AND MA
Page 131 and 132:
CHAPTER 4 ■ TAKING BACKUPS AND MA
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
C H A P T E R 5■ ■ ■Working w
Page 141 and 142:
CHAPTER 5 ■ WORKING WITH FILESYST
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
C H A P T E R 6■ ■ ■Securing
Page 157 and 158:
CHAPTER 6 ■ SECURING YOUR SYSTEMS
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
CHAPTER 7 ■ WORKING WITH APACHEOn
Page 181 and 182:
CHAPTER 7 ■ WORKING WITH APACHEdi
Page 183 and 184:
CHAPTER 7 ■ WORKING WITH APACHE4.
Page 185 and 186:
CHAPTER 7 ■ WORKING WITH APACHE
Page 187 and 188:
CHAPTER 7 ■ WORKING WITH APACHEAl
Page 189 and 190:
CHAPTER 7 ■ WORKING WITH APACHE
Page 191 and 192:
C H A P T E R 8■ ■ ■Making Be
Page 193 and 194:
CHAPTER 8 ■ USING THE COMMAND LIN
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
CHAPTER 9 ■ WORKING WITH TEXT IN
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
C H A P T E R 10■ ■ ■Things G
Page 225 and 226:
CHAPTER 10 ■ THINGS GO IN, THINGS
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
C H A P T E R 11■ ■ ■Tracking
Page 235 and 236:
CHAPTER 11 ■ TRACKING DOWN BUGSTh
Page 237 and 238:
CHAPTER 11 ■ TRACKING DOWN BUGS01
Page 239 and 240:
CHAPTER 11 ■ TRACKING DOWN BUGS
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
CHAPTER 11 ■ TRACKING DOWN BUGSTh
Page 247 and 248:
CHAPTER 11 ■ TRACKING DOWN BUGSAn
Page 249 and 250:
CHAPTER 11 ■ TRACKING DOWN BUGS#
Page 251 and 252:
C H A P T E R 12■ ■ ■Managing
Page 253 and 254:
CHAPTER 12 ■ MANAGING TIME AND PE
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
APPENDIX■ ■ ■Perl TipsSee rec
Page 269 and 270:
APPENDIX ■ PERL TIPS• Date::Par
Page 271 and 272:
APPENDIX ■ PERL TIPSPerl Syntax N
Page 273 and 274:
■ ■ ■Index■Symbols$CDPATH,
Page 275 and 276:
■ INDEXenscript option (printing)
Page 277 and 278:
■ INDEX■NNagiosadding hosts to,
Page 279 and 280:
■ INDEXsyslogcentralized logging
Page 281 and 282:
Download at WoweBook.Com
show all

Linux System Administration Recipes A Problem-Solution Approach

Create successful ePaper yourself

Delete template?

Save as template?