[Last Call] Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

Two ISCSI initiators not seeing the same data on the array

Posted on 2012-08-11
5
Medium Priority
?
734 Views
Last Modified: 2012-08-17
I have two Ubuntu servers connected to the same ISCSI array.  Everything appears fine and I'm able to read the contents of the array from either server.  However, if I write to the array from server A, Server B doesn't see the new files until I disconnect and reconnect to the array from Server B.

Please advise.
0
Comment
Question by:dorianit
5 Comments
 
LVL 56

Assisted Solution

by:andyalder
andyalder earned 1000 total points
ID: 38283690
ou need to use a cluster filesystem, the one you are using has the file allocation table (inode list etc, call it what you  want) stored in RAM. You'll also need a distributed lock manager. GFS will do for Linux.
0
 

Author Comment

by:dorianit
ID: 38283712
so it's currently ext3 or ext4.  You're saying I need a lock manager (GFS)?  Is ext3/4 okay?

thank you.
0
 
LVL 7

Accepted Solution

by:
B_Denison earned 1000 total points
ID: 38283792
You are begging for data corruption doing this without the clustered file system mentioned by andyalder.  This is because both systems have read/write capability to the same storage, but have no way to communicate to each other about what they are writing to which addresses and it's entirely possible - even likely - that the last server to write to a given address over-writes what the other server put there.

A clustered file system will install software on both machines so that they can synchronize what addresses are being 'reserved' for writes to each server and not step on each other.
0
 
LVL 56

Expert Comment

by:andyalder
ID: 38283807
EXT3/4 will not do, there's a list of cluster filesystems here - http://en.wikipedia.org/wiki/Shared_disk_file_system.

The DLM is in addition, I think there are two available for use with GFS. The DLM stops both servers opening the same file at the same time.
0
 
LVL 81

Expert Comment

by:arnold
ID: 38283844
Iscsi targets often are a one to one access.
One host can access the the target at a time. What is the iscsi device in use?
It should include awarding to that effect.
Iscsi sends scsi commands over ip and there is no way, as others pointed out, to have commands processed by node1 dispatched to node2.
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The question appears often enough, how do I transfer my data from my old server to the new server while preserving file shares, share permissions, and NTFS permisions.  Here are my tips for handling such a transfer.
Compliance and data security require steps be taken to prevent unauthorized users from copying data.  Here's one method to prevent data theft via USB drives (and writable optical media).
Learn how to navigate the file tree with the shell. Use pwd to print the current working directory: Use ls to list a directory's contents: Use cd to change to a new directory: Use wildcards instead of typing out long directory names: Use ../ to move…
How to Install VMware Tools in Red Hat Enterprise Linux 6.4 (RHEL 6.4) Step-by-Step Tutorial
Suggested Courses
Course of the Month18 days, 13 hours left to enroll

834 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question