I'm planning a server based on the Dell T440, with two CPUs. This a home/lab environment, not enterprise.

I want to have two VMs - one Windows Server and one Debian Linux.

I want UnRAID to manage a RAID5 array with drives to provide storage for both Windows and Linux.

 

I received one suggestion - "you would want to utilize an HBA controller instead of a traditional hardware RAID array as that standard controller would not be able to run UnRAID"

This post a few years ago suggested LSI. Is that still the best option? I think the T440 by default has the Dell PERC H730P Adapter.

 

Given two identical processors installed in the T440, Is there any special consideration for memory? I understand the RAM can be dynamically allocated between processors so I'd probably start with two 16G DIMMs per processor for a total of 64G. I'll see  how that goes and upgrade to more RAM if necessary. Are there any other considerations for UnRaid use of a two processor server?

 

 

21 hours ago, timg11 said:

I received one suggestion - "you would want to utilize an HBA controller instead of a traditional hardware RAID array as that standard controller would not be able to run UnRAID"

This post a few years ago suggested LSI. Is that still the best option? I think the T440 by default has the Dell PERC H730P Adapter.

You should check this :

 

 

1 hour ago, ChatNoir said:

Great thread over multiple years - thanks! I didn't find that one. I'm thinking DSA-T440-LFF-8-2HS would be a good choice for a RAID5 array, plus a pair of SSD boot drives in parity.

 

You mention RAID a lot, so it is not really clear for me what you mean.

The main component of Unraid is its Array of drives with Parity (simple or double). And by definition, while there is some parity, it is all on dedicated drives and is NOT RAID (as the name implies).

With time, was add additionnal disk Pools that can be single drives (generally XFS) or multi-drives BTRFS and ZFS. Those offer some kind of RAID equivalent. BTRFS RAID5 is generally not recommended though.

 

In any case, in Unraid, everything is Software RAID-like and never proper RAID or HW based.

@ChatNoir I'm using the explanations for RAID5 and RAID6 from Wikipedia - " block-level striping with (single or double) distributed parity"

 

I want to have 5 or 6 16 TB drives that will give me 64 T of total storage with fault tolerance.  The ability to have one drive fail, hot-swap replace it, and have the array rebuild itself.

I have read that I should use an HBA controller to make this work with UnRaid.

Is that type of fault tolerance and redundancy not possible with UnRaid?

 

 

 

 

 

 

Unraid doesn't support hot-swap.

 

The Unraid parity array does indeed give you fault tolerance for either a single or double drive failure depending on whether you assign 1 or 2 parity disks. It is NOT RAID5 or RAID6, the data is NOT striped across devices, each drive has its own valid filesystem. The parity drives are independent from the data drives and hold no sensible data, only the parity bits required to rebuild a failed drive.

 

The advantages of the Unraid parity array is greater resilience and possible power saving, as unused drives can be spun down, also if there are drive failures beyond the tolerance level each remaining data drive remains readable.

 

The disadvantages compared to RAID is speed, as reads are limited to a single device, and writes must update 2 or 3 devices. Also, since each drive is a separate filesystem, any single file can only be as large as the free space on any individual drive.

 

The filesystems from each drive are usable as a group via user shares, which can span multiple drives, each unique root folder on the data drives is a user share, and the file tree view of all those folders is merged when looking at the user share.

 

I suggest looking at some of spaceinvader one's videos on youtube, he has some good basics of Unraid as well as more advanced use cases.

Thanks! I will look at those videos. 

If I wanted traditional RAID with hotswap, could I use a Dell PERC RAID controller with 5 drives and still use UnRaid for managing the NAS and two VMs?

 

 

2 hours ago, JonathanM said:

The advantages of the Unraid parity array is greater resilience and possible power saving, as unused drives can be spun down, also if there are drive failures beyond the tolerance level each remaining data drive remains readable.

Also, the Unraid array allows different sized disks to be used.

4 minutes ago, timg11 said:

If I wanted traditional RAID with hotswap, could I use a Dell PERC RAID controller with 5 drives and still use UnRaid for managing the NAS

You would lose many features of Unraid if you don't allow it to manage each disk.

 

Consider multi-disk ZFS or btrfs pools if you don't want to use the Unraid parity array.

And hotswap is not really that useful for home servers