Author Topic: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI  (Read 4487 times)

dephcon5

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Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« on: August 20, 2009, 12:06:11 pm »
   

I have a TS 1TB with iSCSI and I have two Windows servers. One server is 2003 and the other is 2008. Both can see the Buffalo target and both can write to it, but the 2008 server can only see what it writes and the 2003 server is the same, it only sees what it wrote. Neither can see the others files even though its the same target. They will even write a folder each with the same name and there's no contention.

Any ideas???


Colin137

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #1 on: August 20, 2009, 03:08:43 pm »

Let me confirm something... You are connecting both servers to the SAME volume on the TS? If so, stop that right away. As iSCSI is a block-level storage system, you cannot write to the same volume from multiple computers... this will corrupt the data and make you very unhappy. :)

 

If you want to be able to access the same volume from multiple servers, connect to the volume from one server, then set up the drive on that server to be shared. Then connect to the first server's shared folder of the volume.


dephcon5

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #2 on: August 20, 2009, 08:42:29 pm »
   

"As iSCSI is a block-level storage system, you cannot write to the same volume from multiple computers... this will corrupt the data and make you very unhappy."

 

Well, Im not one for corruption, but this hardly seems to make sense since my NetApp is 100% iSCSI and I have 12 ESX hosts reading and writing to it all day long. As well, its also block level and I have 2 Microsoft Win2K3 clusters using the same volume in an A/P Exchange pair. Also iSCSI.

If the Buffalo cant handle the 2 host servers hitting the same storage then thats one thing, but to say iSCSI cant handle it hardly seems correct. Though... I could be wrong here, Im not an iSCSI expert

 

My goal however is to use the Buffalo as a B2D volume where my 2K8 (Veeam) server will write data and my 2K3 (Backup Exec) server will only read that volume so that data can be backed up to tape.

 


Colin137

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #3 on: August 20, 2009, 10:33:11 pm »

iSCSI has no provisions for shared access to a single volume, it's left to the filesystem. I don't know of a filesystem that works in that manner... NTFS certainly doesn't.

 

I recommend my previous suggestion for shared access. That way you only have one server directly accessing the volume, and the second server accesses it through a Windows Shared Folder.

Message Edited by Colin137 on 08-20-2009 10:33 PM

rinthos

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #4 on: August 21, 2009, 01:10:37 am »
   

dephcon5,

 

Each iSCSI LUN should *only be used by a single server* (not just at a time, but in general) unless:

 

All servers accessing the iSCSI LUN are using a Cluster Filesystem.  W/ your NetApp I assume you're using VMDK's which are indeed cluster disk-supported based on how each ESX host (member of your DRS cluster most likely) is communicating by 'stamping' the LUN to some extent...

For windows, the iscsi LUN should be a cluster resource in cluadmin :)

 

OR

 

Your server has failed and you need to replace it w/ another, so then re-map the iSCSI LUN to a new server which replaces the original single server.

 

To accomplish what you're trying to do, iscsi is not a good fit in your design.  If a SCSI reservation is issued, and your Win2k3 box decides to cache something on the LUN (even though you only want it to read), you could have both servers lose access to the LUN.

 

Your limitation is due to SCSI (not just iSCSI, as the same applies to Fibre Channel, iSCSI, parallel SCSI, serial-attached SCSI (SAS), etc).

 

 

You could:

1) Have 1 server have the iSCSI LUN, and have it create a share on that LUN for which the 2nd server reads the data.

2) Robocopy/xcopy the data to SCSI storage on the second server.

3) Just use the 1 server.

4) Use a different protocol other than iSCSI (CIFS for example given it's Windows).

5) Build a cluster and hope that the Terastation supports cluster's well (i.e. multiple SCSI initiators and the ability to manage scsi reservations appropriately ). :)

 

 

 

Hope this helps.


dephcon5

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #5 on: August 21, 2009, 09:58:14 am »
   

Ok.

I'll hit the target with one machine only and then share that through windows and use that share for the other host servers to connect to that volume.

 

At the end of the day I would have prefered it the other way where both servers hit the target directly, but as suggested earlier I can work around that by sharing the volume and hitting the share. 

Either way, it will work for me :)

 

Thanks for the input from all, much appreciated.


Colin137

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Re: Win 2K3 writes and Win 2k8 cant see it on TS iSCSI
« Reply #6 on: August 22, 2009, 02:10:52 pm »

rinthos,

 

Just a little FYI, the TS iSCSI doesn't support the MS Cluster Service.... not that's you'd want to use the TS iSCSI in that manner anyway, the performance just doesn't cut it in that particular application.