• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

dedicated iSCSI within VM's

C

cyr0n_k0r

Supreme [H]ardness
Joined
Mar 30, 2001
Messages
5,360
From speaking with others about good practices for iSCSI I have been told the following.

VM's within the cluster will be stored on the SAN and the Host nodes will connect with iSCSI. This network would be called "Host_iSCSI"

VM's that host services that also require volumes on the SAN would have a separate but dedicated iscsi network using separate physical nic's that would be passthrough directly into the VM's. I've heard this described as "Gifted iSCSI" but was wondering if anyone has another name for it or can point me to some white papers or best practices. Searching for gifted iscsi doesn't yield much results.

EDIT: It seems people also called it "Direct iSCSI"
http://www.windowsitpro.com/article/storage/whats-iscsi-direct-136363
 
Last edited:
I'm a vmware guy but basically what they are saying is that additional volumes in the VM will write directly to an iscsi target. If you're vm is already on SAN and being accessed through iSCSI I really don't see any advantages performance wise. I believe you will also loose the advantages the Hyper visor gives you possibly effecting things like live motion etc
Not to mention if your iSCSI breaks you will have multiple locations to fix. Your storage administration is going to be a lot more..
 
Last edited:
Wrench00 said:
I'm a vmware guy but basically what they are saying is that additional volumes in the VM will write directly to an iscsi target.
Click to expand...
My post should have been more clear. I'm aware of the concept, and know what Direct/Gifted iSCSI is.
I posted to see if anyone else does this method of iSCSI and if it is common in other virtualized shops.
 
DirectPath IO is not common in any production environment given the extremely limited support for it. TBH, you'll get almost identical performance with vmnics.
 
It has a few use cases that jump out at me:

1.MSCS cluster volumes, like said earlier, being able to vMotion a MSCS cluster node is a great feature..
2. Large volumes(2T+)

Just remember that VM snapshoting tools can't be used to back up these volumes, which could be a good thing.
 
geiger said:
It has a few use cases that jump out at me:

1.MSCS cluster volumes, like said earlier, being able to vMotion a MSCS cluster node is a great feature..
2. Large volumes(2T+)

Just remember that VM snapshoting tools can't be used to back up these volumes, which could be a good thing.
Click to expand...

I found the most misused feature of vmware is vm snapshot. A lot of people use it as a backup.:p

I repeat it again, VM snapshot is evil:cool:
 
VM snaps are perfectly fine for certain (short-lived) things. Like before you apply a major patch/update to a guest. If the update goes south, you just roll back to the snap.
 
danswartz said:
VM snaps are perfectly fine for certain (short-lived) things. Like before you apply a major patch/update to a guest. If the update goes south, you just roll back to the snap.
Click to expand...

That is what it was designed for, but a lot of people don't use it that way.
 
SnapDrive uses in-guest iSCSI. I have an iSCSI VM network for that. I don't dedicate NICs to the VMs though.
 
dilidolo said:
That is what it was designed for, but a lot of people don't use it that way.
Click to expand...

Some enterprise backup solutions use snapshots for LAN-free backups (with help of vStorage API). For example, Symantec NetBackup does it.
So saying snapshots are not good for backups is incorrect. :)
 
geiger said:
It has a few use cases that jump out at me:

1.MSCS cluster volumes, like said earlier, being able to vMotion a MSCS cluster node is a great feature..
2. Large volumes(2T+)

Just remember that VM snapshoting tools can't be used to back up these volumes, which could be a good thing.
Click to expand...

be careful vmotioning a mscs node with in-guest iscsi. I've seen a few times where the stun for the final memory copy can cause a node failover.
 
dilidolo said:
That is what it was designed for, but a lot of people don't use it that way.
Click to expand...

No, the most common use is backup and DR, snap the guest, backup the snapped machine and then delete the snapshot. Almost all vmware backup solutions employ this method as you don't need backup agents on the guests.

Personally I'm not a big fan of iSCSI storage, I use NFS for almost everything except boxes that require iSCSI storage, like Exchange. If you don't have to use it, I wouldn't bother with it.
 
ND40oz said:
No, the most common use is backup and DR, snap the guest, backup the snapped machine and then delete the snapshot. Almost all vmware backup solutions employ this method as you don't need backup agents on the guests.

Personally I'm not a big fan of iSCSI storage, I use NFS for almost everything except boxes that require iSCSI storage, like Exchange. If you don't have to use it, I wouldn't bother with it.
Click to expand...

FWIW, I'm the opposite - it's really a personal preference (NFS vs iSCSI).
 
You must log in or register to reply here.
Back
Top