Encryption FS Type?

[adminmat]

I will be encrypting my drives using the GUI. I noticed that there are several encrypted file system options to choose from. (xfs - encrypted, btrfs - encrypted, etc.) What is the optimal system to go with here?

[Squid]

xfs most stsble

Sent from my NSA monitored device

[adminmat]

Do I use xfs for the array disks and btrfs for my cache? I plan on two NVME drives in RAID1 for cache. 

 

thanks 

[itimpi]

Just now, adminmat said:

Do I use xfs for the array disks and btrfs for my cache? I plan on two NVME drives in RAID1 for cache. 

 

thanks 

That would be normal.   If your cache consists of more than one disk then only btrf is available.

[adminmat]

20 minutes ago, itimpi said:

That would be normal.   If your cache consists of more than one disk then only btrf is available.

Thanks @itimpi. Do you know if the performance issues with using two cache drives in RAID1 have been resolved? 

 

 

[itimpi]

5 minutes ago, adminmat said:

Thanks @itimpi. Do you know if the performance issues with using two cache drives in RAID1 have been resolved? 

 

 

I have no idea I am afraid.  I only have a single drive for cache so use XFS rather than btrfs.

[Derek_]

On 10/5/2019 at 6:14 AM, adminmat said:

Do I use xfs for the array disks and btrfs for my cache? I plan on two NVME drives in RAID1 for cache. 

 

thanks 

 

On 10/5/2019 at 6:15 AM, itimpi said:

That would be normal.

 

I'm new to unRAID and i was about to ask the very same question about which encrypted FS i should use, or at least the differences between them.

 

Why is it normal to use XFS for the array, and BTRFS for the cache? Why not just XFS all round, or BTRFS all round? And what makes Reiser not the preference?

 

Thanks

[John_M]

3 minutes ago, Derek_ said:

Why is it normal to use XFS for the array, and BTRFS for the cache? Why not just XFS all round, or BTRFS all round? And what makes Reiser not the preference?

XFS is simpler and more mature. It suits most people's needs. BTRFS is newer and more sophisticated, offering advanced features, like checksums and RAID. The RAID feature is why it's used for cache pools of more than one disk. ReiserFS is obsolete and no longer maintained. As a simple rule of thumb, if you need to ask then your best option is to accept the defaults.

[Derek_]

26 minutes ago, John_M said:

XFS is simpler and more mature. It suits most people's needs. BTRFS is newer and more sophisticated, offering advanced features, like checksums and RAID. The RAID feature is why it's used for cache pools of more than one disk. ReiserFS is obsolete and no longer maintained. As a simple rule of thumb, if you need to ask then your best option is to accept the defaults.

The default is no encryption, although it does default to XFS sans encryption. Is BTRFS the default if i set a cache drive (i haven't set up any yet). If i have just one cache drive (likely), is there an advantage to BTRFS? Maybe the checksums make it worthwhile?

 

I use EXT4 with LUKS on my PC. EXT4 is kinda the default for Linux distros (so i took your advice before you gave it ). I'm pretty unfamiliar with the others.

 

Thanks for the info.

[John_M]

41 minutes ago, Derek_ said:

If i have just one cache drive (likely), is there an advantage to BTRFS? Maybe the checksums make it worthwhile?

If you have only one cache drive the default is XFS but you can choose BTRFS if you want. If you intend adding one or more drives to you cache pool in the future you might want to choose BTRFS now. At one time, single-disk BTRFS was considered to be less reliable in the event of an unexpected power outage but I don't think that's an issue any more. The checksums allow the Web GUI to offer a scrub option for BTRFS volumes. Advanced users also make use of BTRFS's snapshot facility but at the moment it's only available via the command line. After much experimenting and changing I've settled on using XFS on magnetic disks and BTRFS on SSDs.

[Derek_]

Thanks @John_M. I'll heed your advice and do the same

 

How long does it take for something to move off the cache and onto the storage array?

[adminmat]

To follow up on this I've recently learned that if you use a cache pool with a different file system than the array (like btrfs) when you run the Mover some docker containers / applications become unresponsive. For example when my Mover starts Plex will no longer be able to play anything til the Mover is finished. Even if the movie files were already living on the array. 

 

I may remove one cache drive due to this until its resolved. (if it can be resolved) 

[JorgeB]

4 minutes ago, adminmat said:

To follow up on this I've recently learned that if you use a cache pool with a different file system than the array (like btrfs) when you run the Mover some docker containers / applications become unresponsive. For example when my Mover starts Plex will no longer be able to play anything til the Mover is finished. Even if the movie files were already living on the array. 

That's a v6.7 bug, unrelated to filesystems used, it was resolved in v6.8rc

[adminmat]

4 minutes ago, johnnie.black said:

That's a v6.7 bug, unrelated to filesystems used, it was resolved in v6.8rc

OK good to know. I'm still on 6.6.7. 

[John_M]

1 minute ago, Derek_ said:

How long does it take for something to move off the cache and onto the storage array?

It will stay there until the Mover moves it. By default the Mover runs once a day, sometime during the night, though you can customise it to whenever and how often you want. If you have only a single cache disk, files stored there don't have the benefit of mirrored protection before being moved to the parity protected array - a slight risk but one you should bear in mind. Some people don't use the cache for its original purpose of caching writes to the server now that "turbo write" is an option. Instead they use the cache exclusively for storing docker containers and VMs. Turbo write is an alternative write method to the parity protected array. The traditional write method is known as "read-modify-write" and its advantage is that only the active data disk and the parity disk(s) need to be spinning - the rest can be spun down. It's disavantage is that it's comparatively slow because it spends a lot of time waiting for the disk platters to complete a full rotation between reading and writing (the modification part is very quick). Turbo write, or "reconstruct write" as it's more correctly known, is faster but its disadvantage is that it needs all array disks to be spinning.

[Derek_]

I have to say that i would rather not use the cache to write, unless it then moved to the array in very short order. I will look at what options are available. Sorry, this is somewhat off topic, i shouldn't hijack the original question.

 

Thanks

[itimpi]

1 hour ago, Derek_ said:

I have to say that i would rather not use the cache to write, unless it then moved to the array in very short order. I will look at what options are available.

You can control at the individual share level whether new files written to that share are first written to the cache (and later moved to the array) or whether they by-pass the cache and go straight to the array.   That means you can achieve the balance you prefer between performance and risk.

[Derek_]

On 10/29/2019 at 11:02 PM, itimpi said:

You can control at the individual share level whether new files written to that share are first written to the cache (and later moved to the array) or whether they by-pass the cache and go straight to the array.   That means you can achieve the balance you prefer between performance and risk.

 

Thanks. I did a bit more reading and realised just how much faster using the cache would be, so i will probably go BTRFS in RAID as @John_M uses. I forget sometimes how much the price of SSDs has dropped lately. I think it's worth it   With that, my setup will be using 5 of the 6 storage devices allowed with my license (and all that my mobo can support). I may use the 6th for another SSDs for VMs. Though i was hoping to keep it spare to increase the size of the array in the future.. but that might be 3-4 years away, so i'll worry about that then.

Edited November 1, 2019 by Derek_

[Derek_]

I've set up BTRFS with 2 x 250gb SSDs. I've hunted around and i *think* the default for BTRFS with 2 drives in the cache pool is mirrored. This seems to be evidenced by the fact there's only one folder icon (far right) and the total storage available is ~250gb.

 

Oh, and i've now realised the VMs can be stored on the cache drives (re previous post).

 

As a curiosity. Is it possible to change it to striped? I could not see anywhere to change it (not that i want to).

 

Thanks for your advice earlier

Edited November 6, 2019 by Derek_

[JorgeB]

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=480421