SSD Landing Disk and Duplicated Files

[Kevin]

I just purchased a new SSD for my server but as I've been reading notes about the requirement for two SSDs for duplicated files I am a little worried. Is there any way to disable this requirement? 

 

Thanks!

Kevin

[Christopher (Drashna)]

Yes, and no.

 

Specifically, you need as number of SSD drives equal to the level of duplication you're going to be using.

This is because the Real Time Duplication feature writes to all the necessary disks to ensure that they are properly duplicated.

 

If you disable realtime duplication, it will bypass this issue, but at a cost.

First, files won't be duplicated until a duplication pass occurs (nightly, I believe). That means new files may not be properly protected.

Secondly, files that are kept open (locked) may not be properly duplicated until they're closed.

 

For these reasons, we recommend against disabling real time duplication, and grabbing a second SSD.

[Kevin]

Thank you Christopher for your in depth answer. I'll be looking at getting a second SSD I suppose.

[Christopher (Drashna)]

Well, with how much they've been dropping in price of late.... I'm looking at getting a couple for myself, just to optimize my pool.

[Carlo]

I'm confused by this requirement.  Why the need for 2 SSDs?

 

Isn't the SSD just a "place holder" that get's used to hold the data just long enough until the system can write it out to the HDDs?  Surely one SSD could be used to write the data out to two different HDDs.

 

I'm sure we all get the fact that if two SSDs are used then the files starts out "duplicated" from the start BUT I think most of us could live with the fact that the "temp holding" SSD isn't duplicated until the data is written out to the first HDD.  Or put another way, I'm sure many of us could live with the fact that the data isn't duplicated until the SSD drive has written to at least the first HDD.

 

Could this maybe become an OPTION in a future update?  Something like:

1) Allow use of 1 SSD drive for write caching (data can't be duplicated until first write occurs)

2) Use of two SSD drives for write caching (data is duplicated from the start)

 

Something like that?

[Kevin]

Carlo, Christopher mentions that this is an option but not recommended.

 

First, files won't be duplicated until a duplication pass occurs (nightly, I believe). That means new files may not be properly protected.

Secondly, files that are kept open (locked) may not be properly duplicated until they're closed.

 

[Carlo]

Yes, but that requires you to use a duplication pass and not real-time duplications.

I was referring to being able to keep real-time duplication active but to have the option of only using the one SSD drive.

[Christopher (Drashna)]

Yes, but that requires you to use a duplication pass and not real-time duplications.

I was referring to being able to keep real-time duplication active but to have the option of only using the one SSD drive.

Because the real time duplication feature requires writing to all the disks at the same time. 

 

And considering that SSDs tend to fail suddenly ... what happens if the drive dies in that time between writing the data and pushing it to the HDDs?  We want to prevent that from happening, if possible.

 

Also, if you're writing to folders that are not duplicated, and them moving them to duplicated folders (or not duplicating them ever), then you'd only need one SSD.

 

 

 

Otherwise, it would take a significant rewrite to the driver.