Newbie

[dwchan69]

A total newbie to Unraid, as I just find out about its couple of weeks ago.  So I am curious, doing more research as we speak, the difference between its and FreeNAS.  In short, can anyone address the following few quick questions

 

1. Does UNRAID support NFS or / and iSCSI?

2. How does it handle read and write cache?  Can it setup to leverage SSD / NVMe as cache for write , before it offload to HDD?  Or leverage SSD/NVMe for read buffer?

3. Lastly, does it has any other add-on feature like Plex?

 

Any feedback would be strongly appreciated 

[Hoopster]

14 hours ago, dwchan69 said:

1. Does UNRAID support NFS or / and iSCSI?

2. How does it handle read and write cache?  Can it setup to leverage SSD / NVMe as cache for write , before it offload to HDD?  Or leverage SSD/NVMe for read buffer?

3. Lastly, does it has any other add-on feature like Plex?

1 - Yes, unRAID supports NFS and SMB. AFP also exists in some versions but has been deprecated and will not be supported in future versions.

 

2. - unRAID supports single or multiple cache pools of single or multiple drives for write caching and other uses. Technically, multiple cache pools will not be supported until the 6.9.0 release, but it is in beta now and many users are currently using this version in productions servers.  Single cache disks can be formatted with XFS or BTRFS and multiple drive pools must be BTRFS.    ZFS for array drives is supported via a plugin.  At some point, ZFS may become a standard option.  NVMe or SATA SSDs are supported (as well as HDDs, but what is the point of that?)  There is no read caching concept.

 

3. - unRAID has a very robust and well-supported library of Docker container apps and plugins.  Plex is one of the many supported apps.  There are hundreds of them. Community Apps currently lists 941 apps and plugins for unRAID.  Some are duplicates of the same app, but by different authors.  There are three Plex docker containers, for example.

Edited November 6, 2020 by Hoopster

[dwchan69]

Can you elaborate your comment that "There is no read caching concept"  So my overall read IOPS would be determine only by my spindle count?  I am consider using unRAID in a VMware Lab environment.  Granted write IOPS would be an issue, but so would read.  So I am just curious and want to know the limitation right up front so I can plan accordingly

[JonathanM]

Each drive in the parity protected portion of the array has an independent file system, so reads are limited to the performance of the specific drive that contains the file, no striping. Writes are further restricted by the fact that each write to a data drive is also written to the parity drive(s), meaning multiple drives being written at the same time will slow down to the speed of the parity drive. The writing algorithm can be set to reconstruct write, also known as turbo write, to accelerate the writes, but it means all drives must be spun up to write.

 

Unraid trades high read and write performance for the ability to keep drives spun down when not used, and keeping each drive as in independent file system so failed drives are the only data lost when parity protection is exceeded. If you have an array of 10 drives with 2 assigned to parity, you can lose any 2 drives and they can be emulated and reconstructed. If you lose 3 drives, ONLY the three failed drives will be lost, the remaining drives are still readable, unlike striped RAID volumes.

 

You can also assign drives to cache pools, which can utilize any standard BTRFS RAID levels, striping or mirroring, whatever.

[trurl]

Unraid also trades striping for the ability to use different sized disks in the parity array, and the ability to easily add or replace disks without rebuilding the whole array.