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Old 02-11-2004, 12:45 PM   #1
Gem
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Unhappy Can someone help me set up drbd and heartbeat?


Hi

I currently have 2 Linux boxes. One is the Samba server for the company and one is there just because. I want to set up a cluster between the two machines, and I want to use heartbeat and drbd, but there are some questions just not answered.

1) The first machine uses RAID. Do I have to implement RAID on the second machine in order to have drbd work?

2)Can I use the existing (supported) file system, or do I have to create the file system using drbd (like it seems to say in the documentation I have read)?

I am new to Linux and new to networking in general so I do need some help please and thank you!
 
Old 02-12-2004, 11:06 AM   #2
Gem
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I guess you guys aren't as helpfull to newbies as I have been told. I came here looking for help and no one as even attempted to help me. Thanks for nothing.
 
Old 03-17-2004, 09:35 PM   #3
kridkom
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Re: Can someone help me set up drbd and heartbeat?

hi

even i am trying to set up the same thing cluster between two nodes


drbd + heart baeat on RH 9
were you able to do it? if so kindly let me know the procedures
thanks for help in advance.




kridkom
 
Old 03-18-2004, 12:17 AM   #4
AutOPSY
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Drbd is a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1.



What is the scope of drbd, what else do I need to build a HA cluster?



Drbd takes over the data, writes it to the local disk and sends it to the other host. On the other host, it takes it to the disk there.



The other components needed are a cluster membership service, which is supposed to be heartbeat, and some kind of application that works on top of a block device.



Examples:

A filesystem & fsck.

A journaling FS.

A database with recovery capabilities.





How does it work ?





Each device (drbd provides more than one of these devices) has a state, which can be 'primary' or 'secondary'. On the node with the primary device the application is supposed to run and to access the device (/dev/nbX). Every write is sent to the local 'lower level block device' and to the node with the device in 'secondary' state. The secondary device simply writes the data to its lower level block device. Reads are always carried out locally.



If the primary node fails, heartbeat is switching the secondary device into primary state and starts the application there. (If you are using it with a non-journaling FS this involves running fsck)



If the failed node comes up again, it is a new secondary node and has to synchronise its content to the primary. This, of course, will happen whithout interruption of service in the background.





How is drbd related to current HA clusters ?



To my knowledge most current HA clusters (HP, Compaq, ...) are using shared storage devices, thus the storage devices are connected to more than one node (This can be done with shared SCSI busses or Fibre Channel).



Drbd gives you about the same semantics as a shared device, but it does not need any uncommon hardware. It runs on top of IP networks, which are to my impression less expensive than special storage networks.



Currently drbd grants read-write access only to one node at a time, which is sufficient for the usual fail-over HA cluster. Although it is currently not on my task list, it would not be a great effort to allow both nodes read-write access. This would be useful with GFS for example.
 
Old 03-18-2004, 12:20 AM   #5
AutOPSY
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1) The first machine uses RAID. Do I have to implement RAID on the second machine in order to have drbd work?

2)Can I use the existing (supported) file system, or do I have to create the file system using drbd (like it seems to say in the documentation I have read)?

This is alot easier than you probably think it is.

my question is have you tried using drbd and heartbeat with the two machines.

cause asking a question relating to a sophisticated knowledge in something(which youve shown you have)
then saying that nobody is of much help is retarded.

Why would you have to implement raid on the other machine to use drbd?
 
Old 03-18-2004, 01:09 AM   #6
kridkom
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The question is how to make the data sync in realtime .
and if the primary fails secondary will be online serving the same data and access .if the primary comes online again ip will switch over.

how to set this up,thought drbd will be sufficient but setting it up on red hat is really mind blogging ,
any help will appreciated.
 
  


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