Help me choosing a DAS for my backups and media storage :-)

[iRock1]

Whew, this thread has come full circle

For a home setup, I fall back to my earlier recommendation for a four drive setup. Two drives configured in RAID1 as your primary storage set, 2 drives in RAID0 as the backup data set. I've operated my media library this way for years. If a drive in the primary set goes out you can continue to operate until you get around to rebuilding the mirrored set.

Right, but an array like that considerably limits the capacity of the entire system. With something like you've proposed I'd be stuck in the 4 TB (until we have bigger and cheaper disks).

Since you want a single enclosure, take a look at http://eshop.macsales.com/item/OWC/M3QX2KIT0GB/. You can operate the drives in various configurations from one enclosure. I used OWC for a while when I used FW800, their stuff was always reliable for me.

It was one of the options that I was seriously considering. However, since they seem to have problems with the WD Reds, I'd prefer to buy the Mobius 5-bay.

With an enclosure like that, you can use the built in hardware RAID or OS X software RAID to set two drives as your primary mirrored set and two drives as your striped backup set.

Ok, that's a question that I've always had. Can you set multiple drives as a RAID X, other drives as RAID Y, and others as RAID Z, all in the same enclosure using software tools?

Although RAID of any kind (other than RAID0 for aggregating storage space) is overkill for home use, IMO, RAID5 is definitely unnecessary unless you simply want the "thrill" of toying with it. Set up a reliable backup system like Time Machine first, then tinker with alternative primary storage options like RAID5 if you are so inclined.

Truth is I don't want to toy with anything . I thought a RAID option would be my best alternative because it gives me the possibility of seeing only one partition, where I can drop all my data, while if I've chosen to use something like JBOD, I'd have four different partitions to throw contents at. A pain in the back.

Why did I chose RAID5? Because in terms of redundancy and capacity it's definitely the most balanced option. I don't sacrifice too much space and still I can get things working again if some drive fails. But again, is not that I'm so inclined to one RAID or another, it's just that it looks like the best alternative in my amateur vision.

I insist though. If your think RAID it's overkill, I welcome more suggestions.

 

[iRock1]

Little update: I have purchased five WD Reds (2 TB) for my Oyen Digital Mobius, which is already in transit to his new home.

I have some last-minute doubts though. Would it be recommendable to leave the enclosure on JBOD and make two simultaneous arrangements via software? In this case, the idea is leaving only one drive for backing up my iMac (we are talking about files simultaneously stored in two different locations, so I don''t see any problem), while applying some kind of RAID (RAID1 or 5 perhaps) for the remaining four drives, where I'll be putting my videos.

The other option would be simply leaving the Mobius in RAID 5 (default mode) and then making two partitions – one for Time Machine and the other for my videos. The problem is that I'd be taking up some space in duplicating files that are already duplicated (iMac backups).

 

[matreya]

Little update: I have purchased five WD Reds (2 TB) for my Oyen Digital Mobius, which is already in transit to his new home.

I have some last-minute doubts though. Would it be recommendable to leave the enclosure on JBOD and make two simultaneous arrangements via software? In this case, the idea is leaving only one drive for backing up my iMac (we are talking about files simultaneously stored in two different locations, so I don''t see any problem), while applying some kind of RAID (RAID1 or 5 perhaps) for the remaining four drives, where I'll be putting my videos.

The other option would be simply leaving the Mobius in RAID 5 (default mode) and then making two partitions – one for Time Machine and the other for my videos. The problem is that I'd be taking up some space in duplicating files that are already duplicated (iMac backups).

You should realize that RAID is not a backup. In the instance of RAID 5, it means that if one drive fails, it will rebuild the set when you insert a replacement drive, BUT if another drive fails during the rebuild, you lose all data.

https://www.google.com.au/search?cl...6O0LaeN8QeU9oGYBg#q=raid+5+bad&rls=en&spell=1

Because of this flaw, I keep two RAID5 systems going, one a clone of the other, using Carbon Copy Cloner to mirror the two 9TB RAID5 volumes.

I would strongly recommend you consider doing the same, if you really want to keep your data intact.

As for configuring this Mobius - if you went with JBOD, and used OS X's own software raid, you'd have 1 single drive (non-raid) and two 2TB RAID1 volumes, which may be a PITA to you.. but you could use the non-raid single drive as a Time Machine backup, and keep your video files backed up on the two 2TB RAID1 volumes...

 

[iRock1]

You should realize that RAID is not a backup. In the instance of RAID 5, it means that if one drive fails, it will rebuild the set when you insert a replacement drive, BUT if another drive fails during the rebuild, you lose all data.

https://www.google.com.au/search?cl...6O0LaeN8QeU9oGYBg#q=raid+5+bad&rls=en&spell=1

I know that risk. However, what are the odds of having two drives failing at the same time?

On the other hand, I don't see how is that different from, say, RAID1. AFAIK, if two drives fail (the wrong ones), you are out of luck as well.

Because of this flaw, I keep two RAID5 systems going, one a clone of the other, using Carbon Copy Cloner to mirror the two 9TB RAID5 volumes.

I would strongly recommend you consider doing the same, if you really want to keep your data intact.

I don't think I'll be implementing another RAID system soon. Still, I think it would be a little bit of an overkill just to store movies, concerts, documentaries and TV shows.

As for configuring this Mobius - if you went with JBOD, and used OS X's own software raid, you'd have 1 single drive (non-raid) and two 2TB RAID1 volumes, which may be a PITA to you.. but you could use the non-raid single drive as a Time Machine backup, and keep your video files backed up on the two 2TB RAID1 volumes...

That's exactly what I tried to suggest, though I'm not familiarized with the process yet.

Anyway, I think Disk Utility allows me to do all of that. Would it really be a PITA?

 

[hfg]

That's exactly what I tried to suggest, though I'm not familiarized with the process yet.

Anyway, I think Disk Utility allows me to do all of that. Would it really be a PITA?

Yes, Disk Utility allows you to easily do all that ... and it is NOT a PITA.

If you want a single volume rather than two for your movies, Disk Utility can create a RAID-10 for you by making a RAID-0 out of the two RAID-1 arrays already mentioned. It will have all the capacity in a single volume and twice the speed using the same 4 disks, and you will have 2 disk failure safety. Your total storage space will be that of 2x the disk size, or 4 TB. You still have the single drive for TimeMachine as before with the 5th drive.

 

[matreya]

I know that risk. However, what are the odds of having two drives failing at the same time?

On the other hand, I don't see how is that different from, say, RAID1. AFAIK, if two drives fail (the wrong ones), you are out of luck as well.

Well, I don't know what the odds are exactly, but it's widely regarded as risky to rely on any form of RAID5 without having adequate backups. And RAID 1 is not regarded as a backup either... it's just a level of redundancy that's more straightforward than RAID5.

I've had one RAID5 system lose a single drive, and it rebuilt after inserting a new drive, and hasn't failed in over 2 years so far...

But if your data isn't really important, and worth less than the implementation of a 2nd system to backup the first, it's your decision.

That's exactly what I tried to suggest, though I'm not familiarized with the process yet.

Anyway, I think Disk Utility allows me to do all of that. Would it really be a PITA?

I said 'may' because you seemed to dislike multiple disks in one of your messages...

 

[flynz4]

I know that risk. However, what are the odds of having two drives failing at the same time?

I have had a lot of RAID systems over the years. IMHO... a RAID array is LESS reliable than a single spindle disk. It is counter-intuitive... but RAID is not a good consumer technology. You seem hell bent on RAID. Personally, I think you are suffering some kind of RAID delusions.

There are two reasons why RAID has traditionally had value:

1) Creating a larger volume than is available in a single spindle drive
2) Delivering more performance than available in a single spindle drive

Also... in very expensive enterprise systems (and only enterprise systems)... it also does provide:

3) Data resiliency

Regarding the two listed traditional consumer benefits above... neither have much benefit today:

1) Volume size: With 4TB drives available today... few consumers really need more space in a single volume. If you legitimately need a larger volume... then you are screwed and need some type of RAID.
2) Performance: Anything requiring IOPS, is much better served (about 100X) using an SSD

My recommendation is buy some single spindle drives, and focus on having a robust backup strategy. You will be happier in the long run.

BTW: As a datapoint, in the past decade, I have had 6 RAID arrays in my house. They were a mixture of HW based array boxes, and also 2 HP WHS units. Of those 6 boxes... 5 have eventually died resulting in unrecoverable data loss using RAID recovery. Of course, they were all very well backed up... so I never lost any irreplaceable data.

The one single array that I am currently using is a Promise Pegasus R4. It has been working flawless for a few years now... but I do not count on it retaining data. It is quadruple backed up using a combination of local backup (time machine), 2X local cloning w/ one copy always offsite (Carbon Copy Cloner), and finally (an most importantly), off site automatic backup using Crashplan.

My very strong advice is to NOT consider RAID to be backup. Do not even think of it to be more resistant to data loss. In some ways it can be (loss of a single drive)... but there are many other failure mechanism that a RAID array has that is not present in a single spindle drive. Hence... irrespective of a single spindle vs array... the same level of backup is absolutely necessary.

Given limited budget, you are much better off buying a few single speed drives and using one for data, one for backup... and getting onto a cloud backup service for secondary, automated, offsite backup.

/Jim

 

[iRock1]

I said 'may' because you seemed to dislike multiple disks in one of your messages...

What I don't like is the idea of having four or five different disks on my desk. I wouldn't have a problem handling two partitions (one for external storage, one for backup).

I have had a lot of RAID systems over the years. IMHO... a RAID array is LESS reliable than a single spindle disk. It is counter-intuitive... but RAID is not a good consumer technology. You seem hell bent on RAID.

Absolutely not. I just bend towards what's best for my needs. If you can suggest a way of handling such amounts of information without transforming my desk in a rack of servers, I'll be more than happy to hear it.

Also, how is RAID less reliable than a single spindle disk, from a technical perspective?

There are two reasons why RAID has traditionally had value:

1) Creating a larger volume than is available in a single spindle drive
2) Delivering more performance than available in a single spindle drive

Also... in very expensive enterprise systems (and only enterprise systems)... it also does provide:

3) Data resiliency

Regarding the two listed traditional consumer benefits above... neither have much benefit today:

1) Volume size: With 4TB drives available today... few consumers really need more space in a single volume. If you legitimately need a larger volume... then you are screwed and need some type of RAID.
2) Performance: Anything requiring IOPS, is much better served (about 100X) using an SSD

1) Check. I need more than 4 TB.
2) Not particularly relevant.
3) A nice plus to have.

My recommendation is buy some single spindle drives, and focus on having a robust backup strategy. You will be happier in the long run.

You mean having about four or five single spindle drives. Is that really necessary/recommendable?

BTW: As a datapoint, in the past decade, I have had 6 RAID arrays in my house. They were a mixture of HW based array boxes, and also 2 HP WHS units. Of those 6 boxes... 5 have eventually died resulting in unrecoverable data loss using RAID recovery. Of course, they were all very well backed up... so I never lost any irreplaceable data.

Interesting experience. What specific RAIDs were you working with?

 

[matreya]

What I don't like is the idea of having four or five different disks on my desk. I wouldn't have a problem handling two partitions (one for external storage, one for backup).

I would recommend two RAID systems, one for your media, and one for backing up everything important to you, and big enough to backup your media as well, if you value that.

If you can afford a RAID6 unit for the backup, that would be better than RAID5 because it's more resilient.

I personally have a RAID5 backing up a RAID5 backing up a RAID0. The RAID0 is just for speed, and the dual backups are to ensure I don't lose anything if I experience a catastrophic failure in one backup..

 

[jagooch]

Wow. I have had 1 drive in a RAID array fail, and that was 11 years ago out of a total of 14 years of using software RAID. It is prudent to have an onsite backup and an offsite backup, you can get a combination of Time Machine and Crashplan for that, or just use Crashplan for both.

I currently use FreeNAS on a PC for my 'NAS' media storage, but I'm migrating to DAS and a Mac Mini this month.

For a speedy, I'd go with DAS for the data storage. A Drobo DAS device would get the job done, as long as your Mac has the right plug for it. You could replace it with a NAS if you want to make the storage a standalone system.

Use a single or dual external drive bay connected to your Mac for the onsite backup destination. For offsite I'd use Crashplan cloud backup. It doesn't have a file size or storage limit, has infinite retention for files, and it's dead simple to set up.