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astuni

Forced out of FlexRaid Transparent raid. Coming to Drivepool + Snapraid, need some infos.

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Hello there,

long story short, i had a very well functioning flexraid transparent array which served me well in the past 7 years allowing me to pool my drives and recover data without any issue each time i had failures (i'd say at least 3 drives during this period).

However this month my motherboard died and i had to replace it with a new one, new processor, new ram and that meant i had to reinstall everything from scratch only to find out i can't activate anymore my flexraid license due to developer going into the void with the whole website / domain and the relevant activation server.

This led me to evaluate alternatives and i came across the Drivepool/Snapraid combo.

Now, to my questions:

- I have a grand total of 16 hdds, 15 already filled with data, the last one will be empty and used for parity (i know snapraid recommends at least three parity drives with that many data drives, but i can't afford to migrate to bigger ones right now and my sata ports are all used so it's a no go, i'll take the risk).

- can you confirm i would simply install Drivepool, add all the data drives to the pool, then stop the service, move all the folders into the hidden pool folder on each drive, then start the service again and have drivepool index all the content and show it pooled?

- Flexraid did an awesome job in balancing files across disks, however i have many instances of the same folders (say: TV Shows\baywatch\S01\) on more hdd's and actual files only on some of them, while others could even be empty folders, does Drivepool goes mad when multiple paths with same name are spread across source disks and only some of them have actual files inside them or, like flexraid pooling, it will show the "sum" of them thus showing all the files gathered into that path across all disks?

- How it works if, for some reasons, i have duplicate filenames across source disks for the same paths, it will show either one of the two or it will go mad about them?

Even if i know you don't give actual support for it, do you think it's better to first have drivepool setup (and actual files moved into pooled folders) before having snapraid sync the parity from all the data disks?

Which options i should disable in Drivepool to have snapraid work efficiently (rebalancing and equalization and such things...).

Any other tip you may want to give is welcome, i want to make sure i'm going the right way beforehand.

 

Thank you.

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I'm no expert, but I don't think you need / want to stop the drivepool service when copying / moving all the files to the hidden folder on each drive (as you've written in step 2). I would have thought you set you settings for duplication, balancing, etc, the move the folders with the service running. But i may be wrong....!

I have a couple of simple duplicating pools and  I'm thinking of adding snapraid as well, but I'm not 100% convinced yet... I'd much rather have an integrated system, but I don't think there is one.

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Moving data to the Pool while retaining the data on the same drive is called seeding and it is advised to stop the service first (https://wiki.covecube.com/StableBit_DrivePool_Q4142489). I think this is because otherwise DP might start balancing while you are in the process of moving drive-by-drive.

I am not sure but I would think you would first set settings, then do the seeding.

(I am pretty sure that) DP does not "index" the files. Whenever you query a folder DP will on the spot read the drives and indeed show the "sum". Duplicate filenames will be an issue I think. I think that DP measures the Pool it will either delete one copy (I think if the name, size and timestamp are the same or otherwise inform of some sort of file conflict. This is something you could actually test before you do the real move (stop service, create a spreadhseet "Test.xlsx", save directly to a Poolpart.*/some folder on one of the drives, edit the file, save directly to Poolpart.*/some folder on another drive, start service and see what it does?).

DP does not go mad with same folder names, some empty, some containing data. In fact, as a result of balancing, it can cause this to occur itself.

I have no clue about snapraid. I would speculate that you first create and populate the Pool, let DP measure and rebalance and then implement snapraid. Not sure though. You may have to read up on this a bit and there is plenty to find, e.g. https://community.covecube.com/index.php?/topic/1579-best-practice-for-drivepool-and-snapraid/.

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Umfriend is correct. The service should be stopped to prevent any chance of balancing occurring during the migration when using that method.

And that method is fine so long as your existing arrangement is compatible with DrivePool's pooling structure.

E.g. if you have:
drive D:\FolderA\FileB moved to D:\PoolPart.someguid\FolderA\FileB
drive E:\FolderA\FileB moved to E:\PoolPart.someguid\FolderA\FileB
drive F:\FolderA\FileC moved to F:\PoolPart.someguid\FolderA\FileC
then your drivepool drive (in this example P: drive) will show:
P:\FolderA\FileB
P:\FolderA\FileC
as DrivePool will presume that FileB is the same file duplicated on two drives.

As Umfriend has warned, when it next performs consistency checking DrivePool will create/remove copies as necessary to match your chosen settings (e.g. "I want all files in FolderA to exist on three drives"), and will warn if it finds a "duplicated" file that does not match its duplicate(s) on the other drives.

As to Snapraid, I'd follow Umfriend's advice there too.

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