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I want to setup SAN network, making a couple of computers share the same storage and making computers look SAN as logical drive.

For example and in more details, Computer A has logical drive E and actually drive E maps to SAN. Computer B has logical drive E as well and drive E maps to SAN. For file abc.txt under drive E of computer A, and for file abc.txt under drive E of computer B -- they are of the same file (i.e. modification of abc.txt under drive E of computer A will impact abc.txt of drive E of computer B).

Any general guide for doing this? Vendor neutral guide is appreciated, but vendor specific guide is also welcome.

BTW: I am working on Windows Server 2008 x64 Enterprise.

thanks in advance, George

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1  
If you want a vendor specific guide, it'd help to know who your vendor is... –  rodjek Dec 10 '09 at 14:14
    
No vendor yet, I am doing planning. Maybe HP? EMC? I just want to learn some general knowledge before buying any H/W. Any comments? –  George2 Dec 10 '09 at 15:06

2 Answers 2

up vote 3 down vote accepted

On Windows, you need to use failover clustering for this; you can't simply map the same LUN in two hosts, because nobody would be arbitrating concurrent accesses then, leading to filesystem corruptions. Of course, with failover clustering, only one host at a time will be able to actually access the storage.

If you want two computers to work together on the same drive, you need to share it on a third server and then use plain old Windows networking to access it.

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"you can't simply map the same LUN in two hosts" -- LUN means? –  George2 Dec 10 '09 at 15:07
    
I want to RAID 5, not sure whether it is possible for the same RAID 5 SAN to be able to be accessed by two hosts concurrently? –  George2 Dec 10 '09 at 15:08
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A LUN is (roughly) a virtual disk on the SAN; a volume; something an O.S. can use as if it was a physical disk. –  Massimo Dec 10 '09 at 18:24
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A SAN can and will happily make LUNs accessible by as many hosts as you want; but the the O.S. needs to be able to handle that, or you will get filesystem corruptions. f.e. VMWare ESX handles this automatically with the VMFS filesystem, which was designed for concurrent access; Windows' NTFS was not, so you need a clustering solution (MSCS) to make sure only one host actually accesses the volume at the same time. I'm sure there is something similar in Linux. –  Massimo Dec 10 '09 at 18:26

What you're after is actually more difficult than it sounds. Although you can map the same LUN to multiple hosts (depending on your storage subsystem), you're going to need some sort of distributed filesystem to handle the concurrent writes from the different hosts.

If you were running Linux, i'd recommend OCFS2, any Windows storage admins want to weigh in on this?

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OK, so a quick Google search has recommended Veritas's clustered filesystem for Windows. What's your budget like? –  rodjek Dec 10 '09 at 13:23
    
No vendor yet or budget applied yet, I am doing planning. Maybe HP? EMC? I do not know. Veritas is another option. :-) I just want to learn some general knowledge before buying any H/W. Any comments or recommended readings? –  George2 Dec 10 '09 at 15:09
    
Thanks rodjek, what I want to achieve is, 1. I want to make a continuous growing storage (i.e. if I buy 4T currently, and if in the future 4T is not enough, I can buy another 4T without re-installing OS and be transparent to the application which is using the disk); 2. Reliable, i.e. what stored on the disk is reliable, just like what RAID 5 could provide, not sure whether RAID 5 SAN could achieve my needs? –  George2 Dec 10 '09 at 15:12

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