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Getting right hardware for first RAID setup

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Hi, I'm looking for a little advice/guidance please for my first RAID setup so that I can make sure I get the right hardware.  I've spent days researching all this but there are so many combinations and possibilities I'm struggling to see the wood for the trees.  Here's my current scenario:

  • I have a Mac mini 2018 running 11.3 Big Sur which is on 24/7 as a Plex Media Server and also use it for storing a backup of my music library and other data files.  It runs various automated software for managing the Plex server and content and it's pretty busy in terms of writing and deleting large media files, including for example 4K content. For the most part it's just me watching stuff from the server via Plex either locally or remotely, occasionally another family member watching remotely.
  • For storage I have a 6 year old 4 drive USB 3.0 bay which I originally got for a previous 2012 Mac mini. At present that has 6TB (documents, music, files, non-Plex stuff), 8TB, 10TB and 12TB drives (all Seagate Ironwolf). Free space is scarce except for the 6TB drive that has 4TB free. I think the total used is around 29TB. They've always been used as separate drives.  As I run out of space in one I tend to upgrade for a larger capacity and use the existing drive to replace and retire the smallest drive in the bay.  Recently I've had a couple of instances of a drive locking the whole system and requiring power to be cut to the drive bay. Usually this is a sign a failure is imminent but I have no idea which one as the bay doesn't support SMART reporting.  Logically it would be the 8TB from August 2017 as the other three are from January 2019 but I can't be certain as I once had a drive completely fail within a year with total data loss.
  • I also have a 512GB Crucial X8 SSD which I use for Plex to do transcoding and for storing intermediate download files to speed those up and an 8TB WD Red as a Time Machine backup in a separate USB-C enclosure.

As drives have gotten bigger losing data has become more of a worry and I've been thinking it would be smart to shift to a RAID setup to provide some redundancy and resilience if a drive fails and also to take advantage of the performance gains and Thunderbolt 3 on the newer Mac mini.  A lot of research has led me to thinking the ThunderBays from OWC with a software RAID are the best solution.  The hardware RAIDs I've seen seem to be more NAS or non-Thunderbolt or using their own OS.  The biggest struggle is with the cost of drives with the capacity loss from RAID.  I started off thinking ThunderBay 4 with 4x18TB Exos drives but the drives are crazy expensive still and would likely still be so if I have to replace any.  But I found a good deal on WD UltraStar 12TB drives and wondered if 6x12TB in a ThunderBay 8 might be best and give me the option of future expansion even though I'll only have the same usable space as now.  But looking around the forums it seems I wouldn't be able to add 2 additional 12TB drives to a RAID array in future using SoftRAID.  Am I understanding that correctly that I'd just have two empty slots I wouldn't be able to use?  My budget would already be stretched by the 6 drives so another two on top would be tough and I don't know if it's advisable to add my current 12TB into the mix (assuming it's good) to save on a drive.  If it's a case of now or never for locking in capacity I might have to just try and stretch to 8 drives but I'd like to clarify my options on this.

I've also seen comments that it's better to spread drives across devices for increased security and performance.  The cost difference between buying one ThunderBay 8 or two ThunderBay 4 seems negligible here in the UK (although not many places have stock).  Would it really be beneficial to go down the two ThunderBay 4 route and have them connected to separate Thunderbolt 3 controllers on the Mac mini?  And would SoftRAID handle all that okay in terms of a single RAID array?

In terms of the ThunderBays themselves do they have any kind of protection against power failures?  I've had a couple of outages in the past year and don't know if that's something that fatal with RAID.  Also for the SoftRAID software bundle with the devices I'm not sure what the current situation is as the only ones I'm finding in stock in the UK either have no software or SoftRAID XT Lite which I understand is now discontinued with version 6 so would that even function on Big Sur?  If the 2x ThunderBay 4 was the way to go I think I saw that you needed to purchase a Pro version of the software for multiple devices but is there an upgrade price to that if say the device came with XT Lite?

Lastly (for now at least!) for my use case what would be the recommended RAID type to use?  I've read so many conflicting opinions about RAID 10 vs RAID 5 that I'm not sure what to think.  The gist seems to be that RAID 10 has better performance and rebuilds faster after a drive failure but RAID 5 gives increased usable storage and resilience but is slow to rebuild and vulnerable to further drive failures whilst doing so. I'm not too sure what I should be prioritising here.  Minimising the risk from a drive failure is my main goal.  I've never had multiple drives fail at the same time but don't know if that's more common with an array.  I love the idea of taking full advantage of the Thunderbolt 3 and RAID performance vs my current USB 3.0 bay but don't know if that's just overkill.

Sorry for the long post.  I'm just trying to cover all bases and make sure I make the most informed decision possible given what a huge financial outlay it's going to be.  I'd hate to spend all that to find out a year or two down the road that I'd made a mistake I couldn't easily correct (with the amount of storage I have, transferring off-disk to rebuild a RAID from scratch is never going to be viable).  I figured this was the best place to ask the specifics given the OWC ThunderBays seem to be the best solution.

Thanks in advance for any help and advice and please let me know if there's anything I've overlooked or not taken into consideration.

Topic starter Posted : 28/04/2021 6:10 pm
Member Admin

No we cannot expand a volume by adding drives. Drives generally follow a curve, and as you noticed largest are often the most expensive past the difference in capacity. 8-12TB seems to be the optimal price points currently. Your problem might be too much data for your budget, as you have barely any budgets for backups, as one location for data, even with RAID, is risky.

For enclosures, it is probably best to keep all disks in the same enclosure, as you add electrical points of contact. More cables, more enclsoures, more to go wrong, not less. Note: there is no power /surge protection in Thunderbay's, so you want at least a power conditioner or a UPS that maintains constant power.

RAID 5 is faster than RAID 10. RAID 10 is easier to recover data from in a disaster, but there is a 50% loss of capacity with RAID 10.

The scare stories about large RAID 5 volumes are plain wrong. As a test, we ran a RAID 5 with continual heavy access for over 2 years, without a single corrupted (bit rot) sector. (Same as with Mac Memory, stories about ECC RAM, etc do not apply on Macs') According to the scare stories on RAID 5, we should have averaged one every other month.

Rebuild times are identical with SoftRAID, it depends on the disk, not the RAID level. Also SoftRAID does not degrade performance during rebuilds, unlike hardware RAID.

When you purchase OWC populated enclosures the drives have 3 year warranties, and have already been "certified". Its a bonus feature.

Also, all enclosures you buy, even with SoftRAID XT or Lite XT, will upgrade free to SoftRAID 6.


Hope this helps.

Posted : 29/04/2021 2:49 am
New Member

@softraid-support Thanks for the fast reply, this has certainly given me some extra factors to consider and altered the equation a little.  You're right about the data capacity being a budgetary issue as I'm essentially having to double my already quite large current capacity to get the RAID going.  Backups are something I've struggled with.  Several years ago I had a matching set of drives in a safe which I'd use to manually clone my drives but that became less practical as capacities and costs soared.  I have my most important personal files saved both in the cloud and backed up to the separate 8TB Time Machine drive but this doesn't allow me to backup my media library.  I've tried CrashPlan for offsite backups before too but the software was unreliable and with 18 Mb/s upload on my internet it just couldn't keep up with the amount of data I have. My building is planning to have 1Gb/s download and upload fibre installed hopefully within the next year so that would significantly boost the potential to use something like BackBlaze.  I wonder if there would be a way or if it's desirable to repurpose my existing bay and drives into some sort of backup solution of whether it being USB 3 would be a bottleneck.

Are RAIDs more vulnerable to power outages? They're relatively rare here but do happen.  My drive bay, Time Machine drive and the Mac mini are connected to a surge-protected smart outlet from TP-Link but I don't know if that is enough.  I've looked at UPS before but they seem expensive and offer only a short period of power so I don't know if that would be enough unless they can trigger an auto shutdown.  On a related note would a macOS crash at any point be catastrophic to the SoftRAID? I'll avoid splitting across two devices if you say it increases the risk of issues, it was only because SoftRAID recommended it on the "Go faster" page that I was considering it as an option.

That's interesting what you say about RAID 5 and very helpful thanks because most comments I see tend to say it performs worse and struggles with rebuilds and I mainly see scare stories about second drives failing during rebuilds or UREs.  From what you're saying it sounds like RAID 5 would actually be advantageous in my scenario, especially with giving me more available storage.  Is this down to how SoftRAID works as opposed to hardware RAID?  I've also seen some comments on the SoftRAID site about RAID 6 coming and a RAID 5 being convertible to that.  Is that basically the same as RAID 5 but with an extra drive for protection?

Unfortunately there's extremely limited availability of the ThunderBays in the UK so the pre-populated ones tend to come at a really cost-prohibitive premium over buying the drives separately.  I did read about the certifying feature though and if I've understood correctly that should be the first thing I do when I get the hardware?

Taking into account your info and the pricing/availability it seems I have a few options.  The cheapest would be a ThunderBay 4 and 4x12TB WD Ultrastars which would match my current 36TB usable in RAID 5 but leave me with limited potential for future capacity increase.  The alternative is to get the ThunderBay 8 and increase my overall capacity.  Is there an advantage for my use to having more but smaller drives?  For example there's little price difference between 6x12TB WD Ultrastars (60TB usable) and 8x8TB WD Gold (56TB usable). For some reason the 12TBs are cheaper than the 10TBs which is why I've not considered those. The SoftRAID checker/calculator HERE seems to suggest more of the 8TBs would be quite a bit faster but offer 8TB vs 12TB protection.  And should I not worry about the write speeds it shows for my use? I must admit both those configurations seem like they might be overkill for capacity for RAID 5 whereas when I'd been looking at RAID 10 they seemed essential to get enough. If RAID 5 doesn't rely on mirrors would 5x12TB or 7x8TB work or is it best to stick to even numbers?  Ultimately it'll come down to a balance of cost vs futureproofing as there's nothing worse than watching your free capacity dwindle!

It's great to hear that I won't have to worry about the software upgrade separately if the ThunderBay comes thanks.

Sorry for the extra questions but I think the info you gave me has helped me narrow down my options a little (and made RAID 5 a lot less scary!).  Thanks.

Topic starter Posted : 29/04/2021 6:51 pm
Member Admin


Check out for direct purchasing across Europe.

Here is the Thunderbolt 8 page:

We are also partnering with Acronis for a 1 year trial of Acronis network backup with Thunderbay's, so you can back up all your devices to other devices, like what Crash plan was. Plus Acronis is big on cloud storage/cyber protection. We will do more with Acronis over time.

At the least get a power conditioner. In the US, they are under $100, so you should be able to get for instance a APC Line conditioner for a reasonable price. the idea behind UPS's on your storage is not to keep your drives on line for a long time, but prevent sudden power offs which can damage your data.

Surge protectors do very little and those that do are useless after 6 months of use anyway. Pure marketing.

We gave a talk at several years ago. Watch this video to learn why disk certify is important:
Look for the presentation (6th down on the left)
"How can you avoid the catastrophes caused by disk drive failure" by Tim Standing

Seagate has successfully made a comeback, the Exos and Iron Wolf are pretty reliable. As are the Toshiba and UltraStar (was Hitachi). I am long time skeptical of WD personally. But I am not up to date any longer. I think drives are mostly commodity and marketing, as long as you stay away from SMR recording drives, another topic.


Good luck




Posted : 30/04/2021 2:30 am