Harel's questions

I am trying to deal with a problem on a server I don't normally deal with. Out of the blue a script using ppp started failing saying that the ppp kernel module is not loaded. When I try to modprobe it it complains about files missing. Note below that the kernel version the server thinks it at, does not match the kernel version directory in /lib/modules. I'm not sure how this could have happened. Could the other maintainers of the server botched a kernel upgrade?

My question is how can I fix this discrepancy. Can I simply rename the lib directory and hope for the best? I don't want to break stuff for the people who actually maintain the server but I do need to fix the PPP issue.

$ sudo /sbin/modprobe -v ppp
FATAL: Could not load /lib/modules/2.6.35.4-rscloud/modules.dep: No such file or directory

$ cat /proc/version 
Linux version 2.6.35.4-rscloud ([email protected]) (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) ) #8 SMP Mon Sep 20 15:54:33 UTC 2010

$ ls /lib/modules/
2.6.33.5-rscloud

This is Ubuntu server 11.10.

/dev/sdb is not mounted (see outputs below) and is not used by any process that I can see. Its not used for swap as well. This is a 2nd IDE drive in the server, connected to the secondary IDE and set up in hardware raid as array 2.

I cannot mount the drive as I get a complaint it might already be in use. I did run fdisk, deleted all the previous partitions and created a single primary one.

root@sargent:/home/harel# fdisk -l /dev/sdb

Disk /dev/sdb: 122.9 GB, 122942324736 bytes
226 heads, 63 sectors/track, 16864 cylinders, total 240121728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00083711

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048   240121727   120059840   83  Linux


root@sargent:/home/harel# mkfs -t ext4 /dev/sdb
mke2fs 1.41.14 (22-Dec-2010)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
/dev/sdb is apparently in use by the system; will not make a filesystem here!

root@sargent:/home/harel# cat /proc/swaps 
Filename                Type        Size    Used    Priority
/dev/sda5                               partition   2619388 0   -1

root@sargent:/home/harel# mount
/dev/sda1 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
fusectl on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)

I have 2 switches at the Data Centre - one is connected to the internet, and one for the internal private network.

All servers have one NIC into the internet switch and one to the private one. All servers are ok, except three: Those three servers are visible just fine in the internal network but are unable to ping the internet gateway or be visible from the internet. They have what seems to be the exact same setup in the interfaces and resolve.conf files (with of course different public IP addresses to them but the rest are the same). 'route' shows the same output on those 3 as in another server which works perfectly, yet they cannot access the internet and when I ping the configured gateay from those 3 ping responds that the host is unreachable. When route runs on these 3 machines it pauses a few secons before it displays the gateway (probably as its unreachable).

The servers are all Debian 6. Iptables has no chains/rules.

I've been standing in the Data Centre for the past few hours trying to figure this out. Any help highly appreciated

I'm aware faster disks than what I'm using will help but this will take longer to put in and I am trying to use some emergency measures to decrease disk IO. atop is reporting DSK usage on the red almost constantly. This is for postgres 8.3.

My shared_buffers setting is at 24MB though the server has 16GB of ram which are not fully utilized. My first thought was to give the database as much ram as it could take but I'm not sure how to do that (this is a dedicated database server).

Any solution that does not require a restart is preferable but I'll take what i can get at this point.

Thanks!

I'm about to purchase half a dozen slightly older servers. I see a lot of pretty good specifications quite cheap on ebay. So it won't be the latest CPU but it would still be good enough. The machines will all run Linux (Debian) and will be 64bit.

What brands would you recommend?

What gotchas should I be looking for?

Is any particular features in those slightly mature machines a must have?

Woke up this morning to find out MongoDB grew to all available disk space for some reason. I cannot repair the db to compact it, as I have no space left. I can't even start postgres to remove an old database which would free up a few gigs more. I literally have zero free disk space.

I did delete a 9GB file but the space is not showing up at all when I "df -h".

I have to clear up space on the drive asap as its a production server and we're down. What to do?

We have a linux based environment hosted remotely and a few spare machines in the office. I'd like to use those machines as workers for the remotely hosted application though they would need permanent access to the hosted servers via the private IP subnet. What is the best (and ideally free) way to achieve this?

Am I looking at a VPN solution?

Is there another way to do this other than VPN?

Thanks!

I have a few servers in one rack. They all have 2 network interfaces eth0 and eth1. On all, eth0 has a public IP address assigned which works well. I'm setting up a private subnet on the second eth1 interface, but no matter what I do, the servers can't seem to see each other if i ping them on the 192.168.1.* range. Thanks in advance, Harel

Using 2 servers as an example, neither can ping/ssh eachother via the 192 range:

Server 1:

eth1      Link encap:Ethernet  HWaddr 00:26:b9:76:9d:43  
      inet addr:192.168.1.5  Bcast:192.168.1.255  Mask:255.255.255.0
      UP BROADCAST MULTICAST  MTU:1500  Metric:1
      RX packets:0 errors:0 dropped:0 overruns:0 frame:0
      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
      Interrupt:17 Memory:dc000000-dc012100 


spiderman:/home/harel# ip route show
X.X.X.X/29 dev eth0  proto kernel  scope link  src X.X.X.X 
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.5 
default via X.X.X.X dev eth0 

Server 2:

eth1      Link encap:Ethernet  HWaddr b8:ac:6f:8a:78:fd  
          inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:17 Memory:dc000000-dc012100 

hulk:/home/harel# ip route show
X.X.X.X/29 dev eth0  proto kernel  scope link  src X.X.X.X
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.10 
default via X.X.X.X dev eth0 

Obiously the public ips above are masked as X.X.X.X

There are no iptables rules defined on any server:

hulk:/home/harel# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination