Turn USB RAID enclosure into backup solution; RAID or JBOD?

[dawindmg08]

Been juggling a few different backup solutions in my home, limping by on scattered USB drives and an old Time Capsule that we've outgrown. Don't want to spend the money on a full NAS like a QNAP, thought it might be cheaper to trick out an old USB3 RAID enclosure to handle Time Machine backups from 4 Macs (2 desktops, 2 laptops) so it's just one, central device.

The plan:

1. Swap out current HDDs (very old 500GB Hitachis I think) and replace with 4x 2TB or 1.5TB drives which should cover all of my machines with room to spare.
2. Plug the RAID into a Wireless Hard Drive adapter and then into my router, essentially turning it into a NAS.
3. Mount on each Mac and set it as the Time Machine destination drive.

Questions:

• Are Red or Green HDDs best for this application? I don't think I need the speed of the Reds just for Time Machine backups.
• Should I format as one big Raid or JBOD and have 4 individual disks, one per computer? Which config is best for Time Machine? (I ask because the Time Capsule didn't care how many Macs you backed up to it as long as there was room).
• If I go RAID, should I still partition it so that each computer only mounts a specific volume for backup?
• IS THIS WORTH DOING, or is it a waste of time? I'm trying to reuse my current gear as much as I can, but with the cheapest 1.5TB drives I can find I'm looking at around $224 for all the parts – which is the same price as a 6TB MyCloud drive. Which would obviously be easier but I've had a MyCloud fail before and I really don't trust those.

Thoughts?

 

[sevoneone]

What RAID levels does the enclosure support? Unless redundancy in the event of single drive failing is not important to you or you need all the space on all the drive, I am not sure why you would not use RAID. Since it is a 4 bay enclosure, I'd assume it supports at least RAID 10, a RAID 1 set of two RAID 0 sets. If it supports RAID 5, that is the way to go as you only lose the capacity of one drive and have redundancy from the failure of any one drive.

Also, are any of your Macs a stationary desktop computer? Time Machine Backup Server is now built into macOS 10.13+. Attaching the drive directly to one of your Macs is almost assuredly a better solution than a wireless adapter, especially if it is connected by ethernet. https://support.apple.com/guide/mac...ith-time-machine-mchl31533145/10.14/mac/10.14

Green Drives should be sufficient if all you're using it for is backup.

 

[Mikael H]

I'd assume it supports at least RAID 10, a RAID 1 set of two RAID 0 sets. If it supports RAID 5, that is the way to go as you only lose the capacity of one drive and have redundancy from the failure of any one drive.

Nitpick: RAID10 is generally defined as a striped set of mirrors - a RAID0 of at least two RAID1 sets. Over just four disks there’s no practical difference to RAID01 (what you described), but as soon as you create a RAID set consisting of more disks, RAID10 wins out in resilience over RAID01

Nitpick 2: RAID5 too is a compromise: The cost of the additional available storage space compared to RAID10 is a doubling of I/O traffic when writing data (=performance loss in write-intensive day-to-day usage), radical performance degradation during a disk failure and the subsequent rebuilding process, and with today’s disk sizes, a real risk that a second drive will fail before rebuilding has finished, due to the extended period of high I/O load associated with this process - essentially resulting in total data loss.

@dawindmg08
If you create a logical pool of disk space don’t partition it unless you have to - you’ll kick yourself later if you do. If you really need to limit machines from using more than ”their share” of storage, use software based quotas or similar.

 

[dawindmg08]

If you create a logical pool of disk space don’t partition it unless you have to - you’ll kick yourself later if you do. If you really need to limit machines from using more than ”their share” of storage, use software based quotas or similar.

So here's a question then: I got my USB RAID up and running (RAID 5 since it's 4 disks) and I'm sharing it on my LAN via an adapter (SSK brand) which unfortunately only supports PC file formats, so the main partition is ExFat. I found a hack to make Time Machine work that involves creating Sparsebundles on the drive; I was going to create 4 of these on there, 1 per computer, for backups. I plan on leaving decent overhead in the bundles but I'd rather not create one giant sparse bundle that fills the drive, since the would be 6TB and those take FOREVER to write.

 

[Mikael H]

So here's a question then: I got my USB RAID up and running (RAID 5 since it's 4 disks) and I'm sharing it on my LAN via an adapter (SSK brand) which unfortunately only supports PC file formats, so the main partition is ExFat. I found a hack to make Time Machine work that involves creating Sparsebundles on the drive; I was going to create 4 of these on there, 1 per computer, for backups. I plan on leaving decent overhead in the bundles but I'd rather not create one giant sparse bundle that fills the drive, since the would be 6TB and those take FOREVER to write.

Yes, separate sparse bundles should be an OK solution. You should be able to expand them individually if required, but they still limit the maximum drive usage by each machine and keep the backups separate.

 

[dawindmg08]

Yes, separate sparse bundles should be an OK solution. You should be able to expand them individually if required, but they still limit the maximum drive usage by each machine and keep the backups separate.

Cool, that's what I thought – thanks for the confirmation!

And to correct my earlier post, the sparsebundles only take forever when you try to create them across a network (to a slow USB ExFat drive, no less). I just created them all on my MacBook Pro and a Thunderbolt drive and each one was just a matter of seconds. Copying them over to the USB drive now...