Only seeing some of iSCSI target from Windows 7

Perry

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Sep 22, 2016
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We're setting up a new SAN for our office, running on CentOS 7.

My initial setup is a 29TB RAID0 for the target. The Volume Group, Physical Volume and Logical Volume on the server all show up as 29TB. The server is running CentOS 7, netbsd-iscsi, and I'm doing the administration (including the setup of logical volumes and volume groups) through webmin.

In any case, when I connect to this target from the Windows 7 initiator, it only shows up as a 1TB volume. I'm able to format it in Disk Manager, and it works fine, but you know - it's 1/29th the size of the actual target volume!

Any idea why this volume appears to be the correct size on the server, but Windows 7 only sees a fraction of the available space? I'm not sure if this is a server or client issue, though everything looks right on the server, at least in webmin.

Thanks!
 

pricklypunter

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Nov 10, 2015
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I'm thinking that the array has some odd property. Wipe it completely clean and re-create it as a GPT disk manually using the CLI and try again?
 

Perry

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Sep 22, 2016
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Solved this last night, but was too buried under snow to reply!

The issue turned out to be that (at least in Win7) the Initiator can't see a volume larger than 16GB. It wasn't related to the disk formatting (though I'm using GPT because these are big drives), it's entirely in the initiator software. When I made a small iSCSI target on the server, it worked perfectly. Weird that it only addresses the first TB, but then, well, Windows...

IT actually works out ok, because we really don't need individual targets bigger than 16TB anyway for our workflow, so it's not a problem to make one 30TB physical volume into two <16TB partitions.

Thanks!
 

Perry

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Sep 22, 2016
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Ok, so in fact this isn't solved. I think I must have been very tired or something and made a 16GB volume, not 16TB. I haven't had a chance to play with this for a few weeks, but need to get the system set up in the next few days for some production use.

I wiped out all my logical volumes, formatted a new ~50TB RAID6, and made a logical volume at 8TB. Same problem - it shows up on the server as an 8TB partition on the drive (in gparted), as an 8tb logical volume, and as an 8tb extent in the iSCSI manager. But the Windows 7 native iSCSI Initiator only sees 1.5TB of it. I can mount the volume, but even before I choose GPT or MBR, that volume shows up as only 1.5TB (I can see it in the background behind the Windows dialog telling me to format it first).

If it matters, I'm partitioning the physical drive in gparted, I'm making the Volume Groups and Logical Volumes in Webmin, in LVM v2.02.171

If I need to do this differently I can. I just wanted to try to keep as much in webmin as possible, because it's easier to maintain and visualize the layout, and it's nice to have all this functionality in one place. I'd prefer not to have to maintain it from the command line if I don't have to, but if I do, fine.

Anyway, I know there are several iSCSI implementations for Linux. I'm using the netbsd-iscsi target software because it was the only one I could get to work in webmin. I guess the question remains: is there some kind of limitation with this target software, or is this a problem on the Initiator side?

If it's an initiator limitation, is there a third party initiator that's still maintained for Windows 7? I can only find references to one from Starwind, but they no longer make it, it seems. Our Windows PCs are almost entirely Win7 and we don't want to have to upgrade them all, since they're very stable.
 

pricklypunter

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Nov 10, 2015
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Try sticking a bare copy of Debian on it, install targetcli and see if that rules out your server being the issue?
If the results are the same you know it's likely a windows issue, if it fixes the problem, you know it's likely a server issue. There is the 16TB limit as well to be aware of in windows. Did you just format the disks, or did you zero them with dd? Could there be remnants of a previous config still hiding somewhere on the disks? :)