data deduplication auf unsupported DS und unsupported SSDs

[ctrlaltdelete]

Servus zusammen,
nutzt jemand deduplication auf unsupported DS und unsupported SSDs?
Und wen ja, welche Erfahrungen habt ihr damit gemacht?
Gerne auch Erfahrung mit dedup auf supported Models.

https://github.com/007revad/Synology_enable_Deduplication

 

[Adama]

Ich bin auch letztens über Daves Projekt gestolpert.

Bei mir geht es ja nur auf der 420+. Bei einem ersten Test tauchte bei mir allerdings der Unterpunkt für die Dedup-Einstellungen nicht auf und ich hab das erst mal abgebrochen und werde es später noch mal testen.

 

[Adama]

Also ich hab es noch mal getestet. Ich hatte vergessen, die "Usage detail analysis" zu aktivieren und hatte die Hoffnung, dass es daran liegt.

Aber es funktioniert nur teilweise. Das Skript sagte "Alles Ok", aber der Menüpunkt taucht nicht auf:


Unter den "Global Settings" des Volumes tauchen immerhin die Zeitplan-Einstellungen auf. Die natürlich nur funktionieren, wenn man die Deduplikation aktivieren könnte.

@DaveR I opened an issue in your repository, maybe you can give me some hints, what may went wrong: https://github.com/007revad/Synology_enable_Deduplication/issues/79

 

[DaveR]

@DaveR I opened an issue in your repository, maybe you can give me some hints, what may went wrong: https://github.com/007revad/Synology_enable_Deduplication/issues/79

Did you close a re-open storage manager?

If yes, then I suspect the SSD cache is preventing the deduplication menu from appearing because deduplication is only officially supported on SSD volumes, and an SSD volume would not have an SSD cache.

 

[Adama]

Hi Dave,

I restarted the system before this. That would be enough, wouldn't it?

Have I misunderstood something here? I have a system with hard drives and ssd's as cache. Is this not supported then?

 

[DaveR]

I suspect you didn't run the script with the --hdd option.

I've just released v1.4.29

• Changed to show state of "Dedupe config menu for HDDs and 2.5 inch SSDs" even if --hdd option not used.
  • Now also shows "Run the script with the --hdd option if you want it enabled".

https://github.com/007revad/Synology_enable_Deduplication/releases

 

[Adama]

@DaveR You're right, I started it without --hdd

Reason in your description: Enable data deduplication for HDDs (dangerous)

I thought tiny would be enough...

What is tiny then for? And what is meant by "dangerous" in the description for --hdd

 

[DaveR]

I wrote dangerous because:

• Synology must have a reason for only allowing deduplication on SSDs.
• I don't want to be responsible if people run deduplication on HDDs and something goes wrong.

There's enough people who do run deduplication on HDDs without any reported issues that I should remove that (dangerous) comment.

DSM can do 2 different types of deduplication:

• "btrfs data deduplication" which requires 16GB of memory or more.
• "tiny btrfs data deduplication" which requires 4GB of memory or more.

If your Synology has more than 3GB of memory but less than 16GB the script enables "tiny btrfs data deduplication".

If your Synology has 16GB or more memory the script enables "btrfs data deduplication".

What is the difference between tiny and regular deduplication? Apart from the required amount of memory I honestly don't know. I assume tiny deduplication takes longer.

I should run some tests and time them.

 

[DaveR]

The --tiny option only exists in case someone has a Synology with 16GB of memory but wants to use tiny deduplication instead of regular deduplication. Like if they 8GB of memory allocated to VMs and regular deduplication slows down the NAS too much.

 

[Adama]

Hi Dave,

did use --hdd and now the missing point is shown. As my DS420+ has only 10GB RAM, your script enabled tiny dedup.

Just running a dedup analysis...

 

[Adama]

After more than five hours analysis this is the result:



On a 10 TB volume filled with 6,7 TB:



So in my case, I think it's not really worth it...