Dynamically enable or disable L1 cache?

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danswartz
Posts: 71
Joined: Fri May 03, 2019 7:21 pm

Fri May 03, 2019 7:41 pm

So, in my home lab, I'm in the middle of spinning up two vsphere 6.7 servers. Each host has a server 2016 VM as a storage appliance. I have a ton of ram on each server, so I thought to allocate 32GB or so to each VSA. Here's the thing: when we have a power failure, it's usually for an hour or longer, at which point the UPS has run out, and everything stops dead in its tracks. I had previously been using one vsphere host connecting to a CentOS 7 storage server with direct connect cables, with ZFS providing the storage. To improve write performance (using NFS), I had set sync=disabled, but that is problematic if an outage occurs. Since my lab has an APC UPS, I had apcupsd run a poweroff script when AC power fails, and a poweron script when it restores. The scripts enable or disable sync mode as appropriate. So, my question: is there any way to do this with Starwind? e.g. to have the VSAs query the UPS, and switch the L1 cache to write-through when AC power is lost, and switch back to write-back when it is restored?
Boris (staff)
Staff
Posts: 805
Joined: Fri Jul 28, 2017 8:18 am

Fri May 03, 2019 8:54 pm

Unfortunately, there is no way to dynamically change the operation mode of L1 cache in StarWind VSAN at present.
danswartz
Posts: 71
Joined: Fri May 03, 2019 7:21 pm

Sat May 04, 2019 12:40 am

Ah, bummer. Thanks :)
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Mon May 06, 2019 10:07 am

You are welcome!
bertram
Posts: 16
Joined: Mon Sep 17, 2018 4:09 am

Sat May 18, 2019 6:12 am

Hi,

while it's not possible to dynamically change the operation mode of the L1 cache what procedure could you recommend to perform this in a 2-node converged scenario?

Regards
bertram
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Mon May 20, 2019 2:25 pm

Please find KB article by following this link.
bertram
Posts: 16
Joined: Mon Sep 17, 2018 4:09 am

Wed May 22, 2019 4:47 am

Hi,

is it safe enough to disable the WB L1 cache on only one node to survive a following complete power failure or do you recommend to do it on both nodes?

In case of the second scenario it really becomes tricky because without a built in logic in Starwind it's hard to define which node starts with the process.
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Wed May 22, 2019 8:05 am

The amount of caching should be the same on both nodes.
The cache is HA as well.
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