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ESXi iSCSI datastore 1

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withanh

withanh

IS-IT--Management
Dec 17, 2008
221
US
I have two ESXi hosts that I want to share an iSCSI datastore. I have the first host connected to the datastore. I was able to format it with VMFS and have a VM successfully running on this disk space.

When I connect the second host, it tells me "Warning: The current disk layout will be destroyed. All file systems and data will be lost permanently."

How can I get the second host (and any subsequent ones) to use the same iSCSI datastore without losing any existing data?

Thanks!

h
 
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move the VM to a local Datastore, then let the second node do its thing. Then move the VM back.

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ACTUALLY:
On the 2nd host you'll go to Configuration\Storage Adapters and click Rescan. If the LUN setup is properly done then the datastore will show up

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TechyMcSe2k said:
ACTUALLY:
On the 2nd host you'll go to Configuration\Storage Adapters and click Rescan. If the LUN setup is properly done then the datastore will show up
Click to expand...
I did the rescan and it sees the iSCSI storage. Then I go to Configuration\Storage and it's not there so I add it and that's when I get the lose all data warning.

I may try your first suggestion, but what happens next year when I've got a bunch of VMs running on that datastore and I go to add a new host? I shouldn't have to move the VMs off to add a new host to the group the move the VMs on...

 
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Check this out...

my second post is correct, but if there is an issue with the LUN it wont work. Check the link above and see if it helps.

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Check your iSCSI configuration

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Sorry, I don't know what to check it for. This is my first time with iSCSI and I'm basically teaching it to myself.

The iSCSI box has both hosts allowed for the storage, I tried removing my second host as a test then rescan the storage controller, the disk space goes away, I then add it back as allowed and rescan, the disk space shows up.

 
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Thanks I have that document, that's what I used originally to configure the ESXi hosts to see the iSCSI target.
 
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Your VMFS volume is not flagged as sharable.

Did you create a cluster object in your Inventory? then add both servers to that cluster?

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Brent Schmidt Senior Network Engineer
Keep IT Simple[/color red] Novell Platinum Partner Microsoft Gold Partner
VMWare Enterprise Partner Citrix Gold Partner
 
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Unless there is a checkbox to flag it as sharable, then it is in a sharable state.

My device is an IBM DS3300, so if you're familiar with that it may help.

I have created a host group, added both hosts to the group, assigned the LUN to the host group.

If there is a different/better way to make it available to multiple hosts, please enlighten me as I am extremely new to ESXi & to iSCSI having never used either prior to Monday of this week.

Thanks.
 
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fact Your first ESX host sees the LUN presented by the DS3300, you created a VMFS partition on the LUn to create a datastore. On said datastore, you have created a Virtual Machine that is functional.

fact Your second ESX host sees the LUN presented by the DS330. However, the second host does not present you with the datastore. When you attempt to connect, you are prompted to format the LUN and loose all data (aka, you would blow up your running Virtual Machine).

This is what I get from the information you have provided. Am I understanding you correctly? If these facts are true, then your problem has very little to do with the DS3300. It is doing it's job. Your issue is in your Virtual Infrastructure setup.

In your setup, do you have two pieces of hardware running the ESXi software AND another server running the VMWare vCenter software. You have not said anything about vCenter in your posts. In order to do what you are trying to do, you need a vCenter server.

If you have one, then connect to the vCenter server using the Virtual Infrastructure Client and check on the items I asked about in my previous post. You need to have an ESX cluster object created and your servers need to be a part of that cluster, other wise, your VMFS partitions will not be flagged as sharable (and for good reason).

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Brent Schmidt Senior Network Engineer
Keep IT Simple[/color red] Novell Platinum Partner Microsoft Gold Partner
VMWare Enterprise Partner Citrix Gold Partner
 
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Brent,

The two "facts" you stated are correct.

My ESXi Hosts are in an IBM BladeCenter S Chassis, I have two HS21 blades with the integrated USB flash drive running the embedded version of ESX Server 3i 3.5.0 build-110271.

I have not said anything about vCenter because we do not have/are not running vCenter.

The BladeCenter has integrated storage (we have 12 x 300GB/15k SAS drives). This integrated storage is usable and sharable between the two VM hosts. I have VMs running on them right now, and can manually move them back and forth between the hosts while leaving them in the same place on the shared storage. I accomplish this by building a VM Guest on the 2nd host and telling it to use an existing hard disk image. I then down the guest on the first host and up the guest on the second host, effectively moving it while leaving it on the same storage space.

As you know the issue is with sharing the storage on the DS3300, and if I understand what you are saying, I have to have vCenter to have shared storage from an iSCSI device. Is that correct? I'm not sure I understand why I can have a shared datastore on the integrated storage without vCenter, but not on an iSCSI storage. I know they are not the same, but logically if I can have one shared storage with my configuration, I should be able to have another.

Also, when I created the volume on the DS3300, I told it that it would be used for multiple hosts, which is how the host group got created in the first place, then the 2nd host was added to the group and the LUN assigned to the group.
 
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withanh said:
As you know the issue is with sharing the storage on the DS3300, and if I understand what you are saying, I have to have vCenter to have shared storage from an iSCSI device. Is that correct? I'm not sure I understand why I can have a shared datastore on the integrated storage without vCenter, but not on an iSCSI storage. I know they are not the same, but logically if I can have one shared storage with my configuration, I should be able to have another.
Click to expand...

I haven't had the time to look this up, but to my knowledge that is correct.

On a fiber SAN, I can share datastores between two ESX servers that are not in a cluster, and vCenter is not in use. I can even create an Novell cluster sharing RDM's between virtual machines on two different ESX servers on fiber SAN.

BUT in iSCSI SAN, I can not share datastores between ESX server with out using vCenter, nor can I share RDM's between two Virtual Machines on two different ESX hosts. Not only is the later documented as unsupported, it flat out does not work. You would think it would work, because in theory there should be no difference other than performance, but it just doesn't work.



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Brent Schmidt Senior Network Engineer
Keep IT Simple[/color red] Novell Platinum Partner Microsoft Gold Partner
VMWare Enterprise Partner Citrix Gold Partner
 
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Thanks for the great information. It sounds like I get to spend an extra thousand bucks that I wasn't planning on spending.

Would you explain RDM. I'm not certain what that is.

Thanks!

h
 
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RDM = Raw Disk Mapping.

You prtty much access the disk directly. No creation of a virtual disk on a VMFS partition, the virtual machine will format the disk with it's own native file system and access the disk directly.

You typically want to use an RDM in high I/O situations like a mail system or file server. They have two modes, virtual and physical. A virtual RDM will be included in a snap shot (not a good idea if your disk is large .. eats up disk space on your datastore creting the snapshop). Physical will exclude the RDM from a snap shot, a great idea if you have good backups getting your data and want to utilize snapshots for rapid recovery of the virtual server it's self.

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Brent Schmidt Senior Network Engineer
Keep IT Simple[/color red] Novell Platinum Partner Microsoft Gold Partner
VMWare Enterprise Partner Citrix Gold Partner
 
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Got it. So on my 5.8TB volume, I connected it with iSCSI to a Windows box, then formatted it as NTFS. Not using VMFS and a virtual NTFS image makes this an "RDM", right?
 
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you formated the whole thing?[shocked]

from what you typed, and the way I understood what you said, then no ... that is not an RDM. Those steps you summarize do not compute [pc3] The Windows VM should not know the disk is iSCSI because the ESX server is presenting the LUN to the VM, time to [reading] before you [hairpull3]

0 12117682



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Brent Schmidt Senior Network Engineer
Keep IT Simple[/color red] Novell Platinum Partner Microsoft Gold Partner
VMWare Enterprise Partner Citrix Gold Partner
 
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Yep, formatted the whole thing :)

The KB article didn't help me visualize. I'm struggling with how I can have a VMFS volume that a Windows VM accesses without having a .vmdk that the VM uses...

My test system is a Windows VM with the iSCSI initiator installed and connected directly to the 5.8TB LUN on the DS3300. I did not present the 5.8TB LUN to ESXi because ESXi can only do 2TB LUNs (crazy to say only 2TB) and I'd have to do some type of concatenation to string them together to appear as 5.8TB. At least that's what I understand. I have a couple other threads in this group discussing this. Sounds like I may be just as confused as when I started.



 
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