Server 2012 R2 VMs in ESXi on SSD backed Starwind iSCSI LUNS

Trevbot · Fri Jul 31, 2015 3:17 am

I am noticing that the VMs do not recognize their virtual disks as SSD. In addition, ESXi (5.5 fully patched) does not recognize the iSCSI LUN as SSD either. Is this by design? I ask because I also notice the automatic maintenance task that runs by default on the Server 2012 R2 VMs appears to be defragging the virtual disk since it is not recognized as SSD storage.

Jhon_Smith · Mon Aug 03, 2015 9:58 am

Hello!

Are you using any RAID for those SSDs?
Have you checked if your SSDs are supported by VMware?

Trevbot · Mon Aug 03, 2015 6:48 pm

Storage and Compute separated. The SW SAN consists of SSDs that are connected via LSI9211-8i in IT mode (No raid) and while the OS that SW is running on (Server 2012) recognizes the SSDs correctly, the ESXi host connecting to them via iSCSI does not. Even when the SSD are directly connected to the MB on the SW machine, its the same issue.

darklight · Wed Aug 05, 2015 5:38 pm

Same thing here i assume? https://forums.starwindsoftware.com/vie ... 477#p24477

Trevbot · Sat Aug 08, 2015 1:36 am

Not using HA and the ESXi host(s) can connect to the LUNs just fine, they just do not see them as SSD and as such, neither do the VMs stored on the LUN.

darklight · Mon Aug 10, 2015 12:59 pm

Yeah, that is the way how free version works now i believe. You have to use NFS storage on top of StarWind device to be able to present it to your ESX environment.

Thu Aug 13, 2015 9:59 am

Hi Trevbot,

Regarding your initial question about SSD recognition:
Unfortunately, current StarWind release represents SSDs as HDDs via iSCSI. The fix will be on board in a month or two.

Delo123 · Fri Aug 14, 2015 6:55 am

Maybe you can simply force esxi to see the luns as ssd. they will be marked as ssd in vsphere...

# esxcli storage nmp satp rule add --satp=SATP_TYPE --device eui.80d6xxxxxxxx --option "enable_ssd"
or force all starwind luns
# esxcli storage nmp satp rule add --satp VMW_SATP_ALUA --vendor "starwind" --option "enable_ssd"

Fri Aug 14, 2015 10:30 am

If it possible, then yes, it is a good choice. StarWind knows all SSD specific commands like TRIM and successfully deals with them.

Thanks Delo123

Trevbot · Sat Oct 17, 2015 9:11 pm

Well, good news and bad news. Good news is a modified version of that command with a different claim rule for specific devices (don't use --vendor "starwind" if you have any HDD backed devices as this will cause them to stop responding) will claim the device as SSD after rebooting the host (command needed to be run on each host). Bad news is that the VMs created when SSD backed LUNs were claimed as an HDD still report they are on HDD storage. VMs created after report as SSD. That being said, the VMs should "optimize" rather than "defrag" the drive but reports "Optimization not available." Not a big deal and pretty much expected. Will attempt a few other things to see if previously created VMs can be made to report as SSD.

nohope · Mon Oct 19, 2015 12:46 pm

Hello,

I've already noticed such behavior using other ISCSI server providers. Not sure if it's starwind related issue, looks more like ISCSI protocol limitation. However, it's never been critical for me. There is no impact in performance at all, so I don't see anything you have to worry about. In addition, you are able to mark "SCSI-HDD" device as "Flash" in VMware web-client (vSphere 6.0 supports it for sure).
P.S. The only impact, described in VMware KB article, of SSD ISCSI device presented as "HDD" is not being able to use It for host cache

Thu Nov 05, 2015 10:06 pm

nohope, thank you for your help

Trevbot, do you have any other questions?