Back up in btrfs, safe??

[takkkkkkk]

I was watching new video created by Linus, and I realized he's using unraid array to set up WS to back up day to day PCs.And he's using the btrfs cache to back up "the vault"(I'm assuming another file server). Is this even safe? I thought the idea of the cache drive is that it was for a quick usage, not designed to be a one and only copy file storage.

 

[jonp]

The cache can be used to accelerate writing new files to the system that are intended for the array but it can also be used to store performance centric data (e.g. applications/VMs) perpetually.  Protection for the cache is through btrfs raid 1 (by default), but only if you have more than 1 device assigned to it.

 

Linus setup is an extreme example because he is writing large files over 10gbps network.

[takkkkkkk]

The cache can be used to accelerate writing new files to the system that are intended for the array but it can also be used to store performance centric data (e.g. applications/VMs) perpetually.  Protection for the cache is through btrfs raid 1 (by default), but only if you have more than 1 device assigned to it.

 

Linus setup is an extreme example because he is writing large files over 10gbps network.

 

So why not just use btrfs?? other than file size, as btrfs is raid 10, what benefit does unraid raid provide that btrfs won't? I always thought file back-up should be stored in unraid array, but will the way Linus set-up be secure enough? If so, I wanna start moving away from xfs due to the performance...

[jonp]

 

 

The cache can be used to accelerate writing new files to the system that are intended for the array but it can also be used to store performance centric data (e.g. applications/VMs) perpetually.  Protection for the cache is through btrfs raid 1 (by default), but only if you have more than 1 device assigned to it.

 

Linus setup is an extreme example because he is writing large files over 10gbps network.

 

So why not just use btrfs?? other than file size, as btrfs is raid 10, what benefit does unraid raid provide that btrfs won't? I always thought file back-up should be stored in unraid array, but will the way Linus set-up be secure enough? If so, I wanna start moving away from xfs due to the performance...

 

UnRAID doesn't stripe data like RAID does and each individual disk in the array stores files independent from the others. This eliminates the risk of 100% data loss due to a few drives failing at the same time.  Sure the data on those drives is lost, but the data on unaffected drives is 100% intact (with raid, a few drive failures and all data on all drives is lost). In addition, this means that the same number of drives in an unRAID array could store far more data than in a btrfs pool.

[takkkkkkk]

 

 

The cache can be used to accelerate writing new files to the system that are intended for the array but it can also be used to store performance centric data (e.g. applications/VMs) perpetually.  Protection for the cache is through btrfs raid 1 (by default), but only if you have more than 1 device assigned to it.

 

Linus setup is an extreme example because he is writing large files over 10gbps network.

 

So, Linus shouldn't have used btrfs then? He mentioned for some of the video, this will be the only copy... If that's the case, he really should have used Unraid Array then?

So why not just use btrfs?? other than file size, as btrfs is raid 10, what benefit does unraid raid provide that btrfs won't? I always thought file back-up should be stored in unraid array, but will the way Linus set-up be secure enough? If so, I wanna start moving away from xfs due to the performance...

 

UnRAID doesn't stripe data like RAID does and each individual disk in the array stores files independent from the others. This eliminates the risk of 100% data loss due to a few drives failing at the same time.  Sure the data on those drives is lost, but the data on unaffected drives is 100% intact (with raid, a few drive failures and all data on all drives is lost). In addition, this means that the same number of drives in an unRAID array could store far more data than in a btrfs pool.

[jonp]

So, Linus shouldn't have used btrfs then? He mentioned for some of the video, this will be the only copy... If that's the case, he really should have used Unraid Array then?

 

In a previous post I wrote...

 

Linus setup is an extreme example because he is writing large files over 10gbps network.

 

Write speed to the array would not max out the 10gbps network, which is why he used the cache pool and btrfs instead, because write speed there will be faster.  He prioritized write performance over total usable capacity because his needs are vastly different from an individual using unRAID in a home/SMB environment.

[lionelhutz]

So why not just use btrfs?? other than file size, as btrfs is raid 10, what benefit does unraid raid provide that btrfs won't? I always thought file back-up should be stored in unraid array, but will the way Linus set-up be secure enough? If so, I wanna start moving away from xfs due to the performance...

 

unRAID is one way to build an array of drives while providing protection against a single drive failure. It has advantages in that you can mix drive sizes and that only the parity and data drive being written have to be spinning. Also, when reading only the single data drive you are reading has to be spinning.

 

However, unRAID is not the only way to provide singe drive failure protection. An array of BTRFS drives can also do it. But then, an array of the same hard drives under any linux OS can do it by leveraging the natively supported software RAID (RAID5, RAID6, RAID10 are supported examples). You can also buy a PCIe card that sets up the RAID array at the card level and presents it as a single drive to the operating system. This is often called a hardware RAID solution.

 

You as a consumer really need to look at what you desire and the different products that are available and pick the one best suited to your needs.

 

You could find you like all the features of unRAID except you want to run a BTRFS array for storage. It is possible for you to just use all your drives except one in a BTRFS cache drive array and then use the cache array exclusively to store your data. Being an array, the cache drive is now protected against a disk failing. The "one" drive not in the BTRFS array has to be assigned as a disk in the unRAID array (disk1) to allow unRAID to actually start working. You could use that drive as a "scratch" drive to store unimportant data or temporary data. This sort of defeats the basic principal behind unRAID (the array of parity protected drives) but it is still a way that unRAID could be used.

 

Once again, you have to evaluate if the above is how you want to use unRAID. There are different performance capabilities and data loss risks behind using a BTRFS cache drive array to store data compared to using the unRAID array to store data.