possible to use S3700 SSD as ZIL via RDM in esxi 6?

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epicurean

Active Member
Sep 29, 2014
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I finally got the the right SSD for use as a ZIL for my Napp It VM.

Is it important for the SSDs to be passthrough to the Napp It VM, or lett the VM see them as RDM drives is ok?
 

DaveBC

New Member
Apr 7, 2015
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I have used RDM drives with a napp-it VM and performance was reasonable, though I did not benchmark it against bare metal. My hardware did not allow passthrough.

A big warning though, if a drive goes off line and the VM needs to restart, ESXi will not power the VM back on until the missing drive is removed from the config.
If this is anything more than dev make sure everything is well documented and you know EXACT details on where each drive is physically and where it is assigned virtually.

Is it only slog that you want to use by RDM? What is the rest of your storage configuration?
 

epicurean

Active Member
Sep 29, 2014
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Thanks for the quick response. Yes, its only the ZIL that I want to use RDM SSDs. I have 16 other drives all via passthrough HBAs.
 

epicurean

Active Member
Sep 29, 2014
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any advantage to the use the 2 x S3700 SSDs in RAID 1 as ZIL, as oppose to just stand alone?
 

DaveBC

New Member
Apr 7, 2015
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You have to consider the impact to your workload if you lost the slog unexpectedly. Data is not at risk but if your VMs grind to a fraction of their expected IO performance it might as well be an outage in most environments.
 

epicurean

Active Member
Sep 29, 2014
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Thanks the replies everyone. I have added the RDM drive to my Napp It VM. How do you actually set that S3700 SSD as the SLOG?
 

T_Minus

Build. Break. Fix. Repeat
Feb 15, 2015
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You add it to your pool as a 'log'
I think Napp-IT has it in a drop down menu.
 
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dswartz

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Jul 14, 2011
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Run 'zpool iostat -v 10' and start writes you think should be synchronous. You should see activity on the SLOG device(s).
 
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