StarWind Software

Doing a simple starwind restart today, and after reboot, the volume that configured with WB has lost all the data in the cache, result horriblly corruputed. the volume with write-through is totally fine.

Have been doing this for a while and finally, it bite me hard. I guess that's it, all my data is gone now.

Write-back mode is not expected to be used with a single head (non-HA). And HA does not mean you should not use backups.

So it is unsafe to use the write-back cache in single head (non-HA)?
In Starwind v6, is also unsafe to use the write-back cache in single head?
Assuming, of course, that the raid controller have a battery, and the server is connected to a UPS.

Another question, in v6, is there not the possibility to change the expiration time of the cache? why?

Thanks,

We don't control operating system so it's not safe to use Write-Back cache with anything on a single node. We'll put a disclaimer with a next update. Also we'll have cache expiration control mode. It's legacy setting so far.

DUOK wrote:So it is unsafe to use the write-back cache in single head (non-HA)?
In Starwind v6, is also unsafe to use the write-back cache in single head?
Assuming, of course, that the raid controller have a battery, and the server is connected to a UPS.

Another question, in v6, is there not the possibility to change the expiration time of the cache? why?

Thanks,

What about the scenario where if we have 2-node HA and use the 'mark as synchronized' feature when one node is down -- does the remaining target switch to write-through automatically?

Graham

Yes, 2-way synchronous mirroring configs switch to write-thru from write-back and flush cache immediately after they lose partner. That's why we recommend using 3-way HA as it does not suffer from performance degradation and is much more reliable (military and aerospace grade):

http://www.starwindsoftware.com/why-3-w ... than-2-way

(sorry it's locked by subscription but I guess you have an account and we'll open this PDF in any case)

gstephenson wrote:What about the scenario where if we have 2-node HA and use the 'mark as synchronized' feature when one node is down -- does the remaining target switch to write-through automatically?

Graham