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simple DNS question - reverse nslookup fails.
by vincenzo romero 24 Mar '08

24 Mar '08

Hello all, I am trying to configure a subdomain DNS server on a Cent OS 5.1 - for my lab. Brief configuration: Lab machine ---> 192.168.17.2 (should respond to DNS queries from hosts in 192.168.16.0/20 network) 1. I would also like to forward any queries outside the above network to our corporate domain (no firewalls between our 192.168.16.x network and the corporate network. The domain server is: dns.company.com with an IP of 10.100.1.2 (255.255.255.0). 2. What I have configured is: 192.168.17.2 --> myhost.lab.company.com 10.100.1.2 --> dns.company.com 3. Installed the dns bind 9 in myhost and set basic configuration via the system-config-bind GUI. My configuration file specific to my setup there is: cat lab.maxiscale.com.db $TTL 1H @ SOA myhost.lab.company.com. root.myhost.lab.company.com. ( 2 3H 1H 1W 1H ) NS myhost.lab.company.com. qaserver2 A 192.168.17.3 qaserver1 A 192.168.17.1 myhost A 192.168.17.2 ================= The rest of the DNS/Bind records were based upon the auto-generated files from the Bind GUI Config tool. 3. I also changed myhost's resolv.conf to reflect the following: search lab.mycompany.com 192.168.17.2 search mycompany.com 10.100.1.2 ====== PROBLEM: 1. When I am in myhost.com, I can perform: a. nslookup hostname (to any host within 192.168.x and 10.100.x networks) b. nslookup ip to anyhost wtihin both networks. 2. When I am in one of the hosts within 192.168.x aside from myhost.com (for example, qaserver1 or qaserver2): a: SUCCESS to nslookup hostname to any host within BOTH networks. b. FAILS to nslookup ip (reverse nslookup) to anyhost within the 10.100.x network. this is the error I get: nslookup 10.100.1.2 Server: 192.168.17.2 Address: 192.168.17.2#53 Non-authoritative answer: 24.1.100.10.in-addr.arpa name = dns.company.com. Authoritative answers can be found from: . nameserver = e.root-servers.net. . nameserver = f.root-servers.net. . nameserver = g.root-servers.net. . nameserver = h.root-servers.net. . nameserver = i.root-servers.net. . nameserver = j.root-servers.net. . nameserver = k.root-servers.net. . nameserver = l.root-servers.net. . nameserver = m.root-servers.net. . nameserver = a.root-servers.net. . nameserver = b.root-servers.net. . nameserver = c.root-servers.net. . nameserver = d.root-servers.net. a.root-servers.net internet address = 198.41.0.4 b.root-servers.net internet address = 192.228.79.201 c.root-servers.net internet address = 192.33.4.12 d.root-servers.net internet address = 128.8.10.90 e.root-servers.net internet address = 192.203.230.10 f.root-servers.net internet address = 192.5.5.241 g.root-servers.net internet address = 192.112.36.4 h.root-servers.net internet address = 128.63.2.53 i.root-servers.net internet address = 192.36.148.17 j.root-servers.net internet address = 192.58.128.30 k.root-servers.net internet address = 193.0.14.129 k.root-servers.net has AAAA address 2001:7fd::1 l.root-servers.net internet address = 199.7.83.42 ===== I must be missing something stupid and apparent .... any help would be greatly appreciated!!! :) thanks in advance! -- best, Vince

3 3

smartest way to setup new system (DELL PE 4600)
by Ray Leventhal 24 Mar '08

24 Mar '08

Hi all, One of our servers (very old) died last week and I'm setting up a new CentOS 5.1 box to replace it. Primarily used as a samba fileshare on a mostly windows-workstation network. This system will, ideally, have the OS on a 146 GB SCSI drive, with user data on a 300GB SCSI, both attached to the backplane of the 4600. My question is this: What's best practice and most desirable partitioning for doing this, and how would I go about setting up mirrors of both the OS and the user data drives? Thanks in advance for any help on what I know is a rather newbie question....please chalk it up to lack of sleep and veritable hounding by the 'higher ups' :) Kind regards, -Ray

2 1

Xen or VMWARE on CentOS 5
by Ern jura 24 Mar '08

24 Mar '08

Does anyone out there have a comprehensive tutorial on installing VMware and successfully managing virtual machines with either xen or vmware?

7 10

Health Monitoring
by Ed Donahue 24 Mar '08

24 Mar '08

Hey, I am looking for healt monitoring software for my centos5.1 box. Nothing crazy (like nagios), just something that records memory/cpu usage every min to 5 mins. I added some vmware stuff and was looking to see when if swap gets used and cpu spikes.

3 3

C5 krb5 updates do not get applied
by Bernd Bartmann 23 Mar '08

23 Mar '08

Hi, the latest Centos 5 krb5 1.6.1-17.el5_1.1 do not get applied to any of my servers. I can see the updates being available on the mirror servers, but "yum update" shows nothing. The krb5 updates for Centos 4 were installed on all of my Centos 4 servers without any problem. Does somebody have any idea what could cause the problem on Centos 5? Thanks in advance, Bernd.

3 2

Un Installing a hard drive in a Centos 5.1 box
by Pam Astor 23 Mar '08

23 Mar '08

>>>>>I'm fairly new to Linux and I'm trying to un install a hard drive from my Centos 5.1 >>>>>box running KDE. When I built the PC, I installed two 500 gig maxtors in the tower, >>>>>then I installed Centos. Now I've decided that I want to remove the slave drive and >>>>>use it as an external backup drive - I am mounting it into one of those external >>>>drive cases with a built in fan. >>>>> >>>>>When I physically removed the drive and restarted the PC, centos would not boot up and >>>>>went into a kernel panic. I'm sure I'm supposed to somehow unmount the thing before >>>>>I do this, and that's my question - how do I un-install the hard drive - software >>>>>wise - so that on next boot up, centos don't go crazy looking for it? >>>> >>>>run >>>># mount >>>>this will show the mounted partitions. find the partitions that are on >>>>the second drive and unmount them: >>>># umount /path/to/partition >>>>if a service uses them, you'll see an error. you will need to fix the >>>>errors until you can unmount them. >>>>then comment out these partitions in /etc/fstab. >>> >>>OK this is what I have when I run mount - does it appear that >>>I have both drives on one volume?: >>> >>> >>> /dev/mapper/VolGroup00-LogVol00 on / >>>type ext3 (rw) >>>proc on /proc type proc (rw) >>>sysfs on /sys type sysfs (rw) >>>devpts on /dev/pts type devpts >>>(rw,gid=5,mode=620) >>>/dev/sda1 on /boot type ext3 (rw) >>>tmpfs on /dev/shm type tmpfs (rw) >>>none on /proc/sys/fs/binfmt_misc type >>>binfmt_misc (rw) >>>sunrpc on /var/lib/nfs/rpc_pipefs type >>>rpc_pipefs (rw) >> >>If the machine panics at boot time, there is a good chance that you >>installed with LVM and its got both the drives into one volume. You will >>need to reinstall that second harddrive, then work out the process of >>shrinking the filesystem down to only 1 drive, then remove the second >>drive. The scope of this work might be too much for an email, so I can >>best point you at the LVM HowTo. There are also some good lvm tips in >>the CentOS5 docs ( http://www.centos.org/docs/5/ ) >> > >am Astor wrote: >> OK this is what I have when I run mount - does it appear that >> I have both drives on one volume?: >> >> /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw) >> >> >>what output to do you get from : >>pvdisplay; vgdisplay; lvdisplay >[root at localhost ~]# pvdisplay; vgdisplay; lvdisplay > --- Physical volume --- > PV Name /dev/sdb1 > VG Name VolGroup00 > PV Size 465.76 GB / not usable 9.50 MB > Allocatable yes (but full) > PE Size (KByte) 32768 > Total PE 14904 > Free PE 0 > Allocated PE 14904 > PV UUID IAmE1f-dCMo-c035-cSQQ-g9yE-6yOo-mfKhHv > > --- Physical volume --- > PV Name /dev/sda2 > VG Name VolGroup00 > PV Size 465.66 GB / not usable 3.56 MB > Allocatable yes (but full) > PE Size (KByte) 32768 > Total PE 14901 > Free PE 0 > Allocated PE 14901 > PV UUID fi5A7U-dao0-ruuP-TSc0-LfFu-7yRL-iKnwGr > > --- Volume group --- > VG Name VolGroup00 > System ID > Format lvm2 > Metadata Areas 2 > Metadata Sequence No 3 > VG Access read/write > VG Status resizable > MAX LV 0 > Cur LV 2 > Open LV 2 > Max PV 0 > Cur PV 2 > Act PV 2 > VG Size 931.41 GB > PE Size 32.00 MB > Total PE 29805 > Alloc PE / Size 29805 / 931.41 GB > Free PE / Size 0 / 0 > VG UUID pwO7bQ-0eRs-W8O4-b4uf-hYe6-JIm6-27p8wu > > --- Logical volume --- > LV Name /dev/VolGroup00/LogVol00 > VG Name VolGroup00 > LV UUID avhFcY-30N6-2BPz-A89X-Ai0V-v5B7-xxzhIe > LV Write Access read/write > LV Status available > # open 1 > LV Size 929.47 GB > Current LE 29743 > Segments 2 > Allocation inherit > Read ahead sectors 0 > Block device 253:0 > > --- Logical volume --- > LV Name /dev/VolGroup00/LogVol01 > VG Name VolGroup00 > LV UUID ZW2z5f-5x58-0vDI-ru5S-iZge-mVE6-yVp160 > LV Write Access read/write > LV Status available > # open 1 > LV Size 1.94 GB > Current LE 62 > Segments 1 > Allocation inherit > Read ahead sectors 0 > Block device 253:1 > >And... > >[root at localhost ~]# df -h >Filesystem Size Used Avail Use% Mounted on >/dev/mapper/VolGroup00-LogVol00 > 901G 6.7G 848G 1% / >/dev/sda1 99M 18M 76M 20% /boot >tmpfs 1.9G 0 1.9G 0% /dev/shm >[root at localhost ~]# >yup, its all 1 Volume, you are going to need to shrink the lv's - then >get your volgroup onto /dev/sda only. info on howto do that is in the l>vm howto. also, I'd recommend you download the centos-5.1/livecd and >actually do the work once booted from the livecd. shinking filesystems >requires you to have the filesystem unmounted, so doing it from the >livecd is the only way you are going to manage it here. OK when you say livecd, do you mean the Centos 5.1 distro disks? I have a full set of them, a 7 disk set I got from Linux Central. Can I just boot off disk 1 from my set? ...or, if I left the install the way it is now, are there any dis advantages of leaving the file system the way it is - spread over two hard drives? Should just get another hard drive and back it up the way it is? Would ther be any problems with my backup if left the way it is? Or ahould I just do a complete re install of the OS after backing up my data... What do you reccomend -leave it as is, re configure it, or re install it? _________________________________________________________________ How well do you know your celebrity gossip? http://originals.msn.com/thebigdebate?ocid=T002MSN03N0707A

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md raid1 - no speed improvement
by Kieran Clancy 23 Mar '08

23 Mar '08

Hi, I have two 320 GB SATA disks (/dev/sda, /dev/sdb) in a server running CentOS release 5. They both have three partitions setup as RAID1 using md (boot, swap, and an LVM data partition). # cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[1] sda1[0] 104320 blocks [2/2] [UU] md1 : active raid1 sdb2[1] sda2[0] 4192896 blocks [2/2] [UU] md2 : active raid1 sdb3[1] sda3[0] 308271168 blocks [2/2] [UU] When I do tests though, I find that the md raid1 read performance is no better than either of the two disks on their own # hdparm -tT /dev/sda3 /dev/sdb3 /dev/md2 /dev/sda3: Timing cached reads: 4160 MB in 2.00 seconds = 2080.92 MB/sec Timing buffered disk reads: 234 MB in 3.02 seconds = 77.37 MB/sec /dev/sdb3: Timing cached reads: 4148 MB in 2.00 seconds = 2074.01 MB/sec Timing buffered disk reads: 236 MB in 3.01 seconds = 78.46 MB/sec /dev/md2: Timing cached reads: 4128 MB in 2.00 seconds = 2064.04 MB/sec Timing buffered disk reads: 230 MB in 3.02 seconds = 76.17 MB/sec If I fail and remove one of the disks in /dev/md2: # mdadm /dev/md2 -f /dev/sda3 # mdadm /dev/md2 -r /dev/sda3 # cat /proc/mdstat ... md2 : active raid1 sdb3[1] 308271168 blocks [2/1] [_U] # hdparm -tT /dev/md2 /dev/md2: Timing cached reads: 4184 MB in 2.00 seconds = 2092.65 MB/sec Timing buffered disk reads: 240 MB in 3.01 seconds = 79.70 MB/sec So with only one disk in the array the performance is pretty much the same. At first I thought maybe the bottleneck is the SATA controller, but if I do simultaneous reads from both disks: # mkfifo /tmp/sync # cat /tmp/sync; hdparm -tT /dev/sda3 (and in another terminal, to make sure they start simultaneously) # > /tmp/sync; hdparm -tT /dev/sdb3 /dev/sda3: Timing cached reads: 2248 MB in 2.00 seconds = 1123.83 MB/sec Timing buffered disk reads: 234 MB in 3.00 seconds = 77.91 MB/sec /dev/sdb3: Timing cached reads: 2248 MB in 2.00 seconds = 1123.74 MB/sec Timing buffered disk reads: 236 MB in 3.01 seconds = 78.30 MB/sec So the total cached read bandwidth seems limited to about 2250 MB/s, which is slightly higher than the cache read bandwidth for /dev/md2, but I'm not too worried about that. More concerning is that I am still getting ~80MB/s from each disk simultaneously on the buffered reads. Given this I would expect /dev/md2 to give buffered read speeds of at least 120MB/s (if not 150MB/s). What can I do to track down this issue? Any help would be really appreciated. Thanks, Kieran Clancy.

6 5

Re: CentOS Digest, Vol 38, Issue 23
by Sam Drinkard 23 Mar '08

23 Mar '08

Ann, Actually I had to add read / execute permissions to the aliases.db to stop the error messages. I'd just like to know what clamav is doing to it or why it needs to read it. I installed the clamav with yum but for some reason it does not know it's in there. How to fix? Sam

2 1

about smbldap tools
by Arwen Smith 22 Mar '08

22 Mar '08

Hello List I'm installing a PDC with ldap using smbldap tools (IDEALX) it's allready configured but when i try to add an user using smbldap-useradd -m user it throw the following error: Error looking for next uid at /opt/IDEALX/sbin//smbldap_tools.pm line 993. can any body help me regard Roilan ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping

2 1

PHP Segfaults on Centos 5 and PBX in a Flash but not Trixbox
by Nigel Kendrick 22 Mar '08

22 Mar '08

Hi Guys, Any known reasons why PHP 5 (Centos 5) might be segfaulting on an Asus A7V8X mobo with an Athlon 2400XP (1GB RAM). Everything else works fine and I had done some system/RAM tests so I am pretty sure the hardware's OK. Here's what I have found: Vanilla CentOS 5 - PHP segfaults yum remove/install PHP on above - PHP segfaults PBX in a Flash iso (based on CentOS5) - PHP segfaults Latest Trixbox (CentOS 5) iso (PHP 5.2.2-3) - OK I wonder if it may be down to compiler or optimisation flags. Any thoughts - Ideally I want to run PBX in a Flash. Thanks Nigel Kendrick

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