RAID 5 vs RAID 6 ??

Hi all,

Would love to get your thoughts on the best RAID type for video editing off a NAS system.

I just purchased a QNAP TVS-h874-i5-32G 8 Bay NAS, which I will be populating with 14TB WD Red Pro drives. I anticipate needing a lot of storage for my project, around 100TB… the end goal is to work remotely with other editors in assembling the footage.

All of the footage is and will be backed up multiple times to other archival hard drives.

I’ve heard conflicting things about RAID 5 vs RAID 6 for video editing, and I’m not sure whether losing two drives worth of space in my NAS is reasonable for “safety” since I don’t know how long it actually takes a 14TB drive in a RAID 5 to rebuild in case a drive dies and I swap in a new one right away…

I have also heard that RAID 6 is a lot slower in building and rebuilding. Some people think RAID 5 is a terrible idea that’s doomed to fail, but it seems to me if the data is fully backed up elsewhere the odds of a second drive dying during the time (1 or 2 days ??) it takes for the NAS to rebuild one drive is fairly slim, and even if so, the backups could always be used to redo the whole RAID from scratch…. But since this will be the first time, I create a RAID of any kind, maybe I’m underestimating how much of a PIA this will be in terms of time spent if a second drive failed?

Appreciate your thoughts!

14 TB can take days. Use raid 6 or preferably 10.
For video editing, you should be using DAS - direct attached storage rather than a NAS if you need speed for NLE. Forget others connecting in and editing from across the internet. Use the NAS as storage for convenience and file transfer.

Can't recommend RAID5 or 6 - RAID10 is my recommendation for your use case.

RAID5/6 have good read speeds, but writes are limited to the performance of a single disk.

degrub said:

14 TB can take days. Use raid 6 or preferably 10.
For video editing, you should be using DAS - direct attached storage rather than a NAS if you need speed for NLE. Forget others connecting in and editing from across the internet. Use the NAS as storage for convenience and file transfer.

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Many people edit remotely from a NAS... hmm, not sure why you think this would be an issue?

sfx2000 said:

Can't recommend RAID5 or 6 - RAID10 is my recommendation for your use case.

RAID5/6 have good read speeds, but writes are limited to the performance of a single disk.

Click to expand...

Editing is almost entirely a disk-reading process.

When you get into RAID with really big drives, RAID10 can be a good option. You end up with less space.

Ariaelf said:

Editing is almost entirely a disk-reading process.

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Most folks that I know that work on AV production - they run Macs because of Thunderbolt 3/4...

Mac Studio (Max or Ultra) with a bank of TB3 drives and 10Gbe is the norm over there.

4K and 8K footage needs that - and heck, with the current crop of smart phones, 4K is getting fairly common on the high end...

Direct Attached storage is always nice and preferred over even high performance NAS boxes...

degrub said:

14 TB can take days. Use raid 6 or preferably 10.

Click to expand...

14TB on an 8 disk array to rebuild - it'll take some time...

One of the risks of RAID5/6 - when one dies, others will join the funeral and at a most opportune time as rebuilding a RAID5/6 array is very read intense...

RAID10 - lose a disk and replace it, no performance impact...

One thing to note - with OP's QNAP TVS-h874-i5-32G - it supports ZFS via QuTS Hero...

There, let it build the array out as a default, and spares replacement is a bit easier to deal with.

coxhaus said:

When you get into RAID with really big drives, RAID10 can be a good option. You end up with less space.

Click to expand...

"less space" is why I wouldn't use RAID10, nor do most editors. It's always RAID5 or RAID6 as far as I understand.

the OP said I needed ~ 100 TB of space and have (8) 14TB drives. You're suggesting to cut the space in half, which means you either didn't read the post or didn't understand the assignment

sfx2000 said:

Most folks that I know that work on AV production - they run Macs because of Thunderbolt 3/4...

Mac Studio (Max or Ultra) with a bank of TB3 drives and 10Gbe is the norm over there.

4K and 8K footage needs that - and heck, with the current crop of smart phones, 4K is getting fairly common on the high end...

Direct Attached storage is always nice and preferred over even high performance NAS boxes...

Click to expand...

I have a PC with Thunderbolt connections... Mac is not required.

As stated in the OP, the goal is to work with remote editors online, so DAS would be pointless. The question is about a NAS which I already have... not sure why every reply seems to be suggesting some other scenario or endpoint than the one I asked about.

sfx2000 said:

14TB on an 8 disk array to rebuild - it'll take some time...

One of the risks of RAID5/6 - when one dies, others will join the funeral and at a most opportune time as rebuilding a RAID5/6 array is very read intense...

RAID10 - lose a disk and replace it, no performance impact...

One thing to note - with OP's QNAP TVS-h874-i5-32G - it supports ZFS via QuTS Hero...

There, let it build the array out as a default, and spares replacement is a bit easier to deal with.

Click to expand...

I'd really like a better idea of what "some time" means. 12 hours? 12 days? 12 weeks?

As far as intensity, a video editing RAID is read-intense all the time. That's what video editing is, constantly scrubbing through data - so I'm not sure why a rebuild would be more intense or more likely to destroy a second drive than whatever dumb luck causes drives to die ordinarily....

ZFS would be the plan. Can you elaborate what you mean by "let it build the array out as a default" ??

Ariaelf said:

"less space" is why I wouldn't use RAID10, nor do most editors. It's always RAID5 or RAID6 as far as I understand.

the OP said I needed ~ 100 TB of space and have (8) 14TB drives. You're suggesting to cut the space in half, which means you either didn't read the post or didn't understand the assignment

Click to expand...

It gets a little dangerous with large drives running RAID5 or RAID6. The rebuilds take a really long time. RAID10 is more friendly with large drives but you do lose more space.
I would not consider it using RAID5 or 6 with BIOS RAID and large drives. I would want an Intel RAID card or a Dell RAID card.

In perfect world you shall create zpool z2 and add ssd/nvme as cache to it.

coxhaus said:

It gets a little dangerous with large drives running RAID5 or RAID6. The rebuilds take a really long time. RAID10 is more friendly with large drives but you do lose more space.
I would not consider it using RAID5 or 6 with BIOS RAID and large drives. I would want an Intel RAID card or a Dell RAID card

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Not "more space" ... HALF THE SPACE in the becomes unusable. I'm not sure why you keep pushing RAID 10 when it goes against everything outlined in the OP goals. RAID 10 is neither cost or space effective for video editing.

"Really long time" meaning what? Hours? Days? Weeks? Vague generalities are not helpful. I've outlined all the specs, and would like to hear from someone who has experience with RAID 5 vs RAID 6, or rebuilding 14TB or similar size drives.

Adooni said:

In perfect world you shall create zpool z2 and add ssd/nvme as cache to it.

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Since this is my first RAID build would you mind explaining what you're talking about? The ssd cache I get, but what about the z-stuff? And how does this answer the RAID 5 vs 6 question...?

you need to build ZFS Zpool https://wiki.ubuntu.com/ZFS/ZPool

please read about differences and similarities
https://www.klennet.com/notes/2019-07-04-raid5-vs-raidz.aspx

and you add to it HDD for Z1/ Z2 min 4/5HDD and SSD with logs and cache - I am using it from 2015 and do not have any challenges. I download torrent with 1Gb/s and share those too. Writing speed is not a issue and backup too. I stopped use raid 5,6,10 -9y ago. just google it there are big advantages using raidz

Ariaelf said:

RAID 10 is neither cost or space effective for video editing.

"Really long time" meaning what? Hours? Days? Weeks?

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Nobody ever accused RAID10 of being cheap - that's not the point of it.

The different RAID options give you a choice between speed, size, cost and availability. The question you need to answer is how long can your array be down for before its a problem - and given the backups are on lots of different disks, how much of your own time do you have to dedicate to the recovery (rather than just leaving it to sync for over a week before you can use it which is what it will probably be).

As far as intensity, a video editing RAID is read-intense all the time. That's what video editing is, constantly scrubbing through data - so I'm not sure why a rebuild would be more intense or more likely to destroy a second drive than whatever dumb luck causes drives to die ordinarily....

Click to expand...

The risk of RAID5 and RAID6 during recovery is on the fact during recovery you do a full read of every single disk. The first couple of recoveries will probably be OK but after that it gets dicey as the remaining disks all have significantly more wear than the others - and there's no going back or undoing that damage. If you're doing something that's read intensive in the first place that makes this worse.

Where RAID10 really comes in to its own is a large array with more disks - RAID5/6 can be lethal in that environment but RAID10 limits the risk and doesn't put excessive unnecessary wear on the whole array.

Personally I've gone back and forth in my mind on the benefits of RAID5/6 vs RAID10 on a home system but it all comes down to an individuals requirements - is it an annoyance if you lose it all but you shrug your shoulders and carry on or is it project over if the array is down for a week or 2 to recover etc.

Ariaelf said:

I'd really like a better idea of what "some time" means. 12 hours? 12 days? 12 weeks?

Click to expand...

Hard to tell - based on personal experience, RAID5 on a 4 disk array takes about a day to sync and build out the parity blocks, and that is generally limited by the speed of the drives - the parity calculation isn't very CPU intense, so that's not a limiting factor there.

Upside though is that once the process is started, you can start writing to the array, don't need to wait for it to finish.

Ariaelf said:

As far as intensity, a video editing RAID is read-intense all the time. That's what video editing is, constantly scrubbing through data - so I'm not sure why a rebuild would be more intense or more likely to destroy a second drive than whatever dumb luck causes drives to die ordinarily....

Click to expand...

The challenge with any array is on the rebuild in case of a failed disk replacement - that is where things can go bad, esp if all the drives are from the same batch from the factory - remember that the risk is inverse - the more drives in the array, the higher the chance of any one disk going bad - it's just part of the territory.

RAID5/6 increases that risk of secondary disk failure compared to RAID10 - RAID10 just does the block level copy from the paired disk in the set, and doesn't have to read all the blocks on all the disks (along with redo'ing the parity) - this is where folks get into trouble with RAID5/6.

Ariaelf said:

ZFS would be the plan. Can you elaborate what you mean by "let it build the array out as a default" ??

Click to expand...

QNAP has a pretty good setup wizard that will walk one thru the steps, and their defaults are pretty reasonable.

sfx2000 said:

One thing to note - with OP's QNAP TVS-h874-i5-32G - it supports ZFS via QuTS Hero...

Click to expand...

BTW - that's a pretty nice NAS - keep in mind that it's not a backup, but a working store - I do suggest keeping content and archival footage on other media for backup purposes.

With such large capacity drives, I would avoid RAID 5. And due to the large number of drive (meaning higher risk of failure on a rebuild), I would consider RAID 6 as a minimum, provided you do have a reliable backup in case of additional failures during a rebuild.

Ideally, I would have considered getting higher capacity drives and going RAID 10 (to improve performance and also better protection in case of failures).

If that NAS supports it, consider adding an SSD cache. If an editor is doing a lot of scrubbing in a project, having that data in an SSD cache can greatly help performance (I assume you have at least 2.5 Gbps, or even 10 Gbps Ethernet). Go for a quality SSD that has a higher endurance rather than cheaper/higher performance ones.

Regarding rebuild times - my own QNAP has three 10 TB in RAID 5. I run a RAID scrub once per month, that scrub (with priority sets to either low or medium, I forgot) takes about 15-18 hours. So with 14 TB, it would be reasonable to assume somewhere around 24 hours of rebuild/scrub time.

That scrub, in addition to ensuring data integrity, also helps having early detection of disk failures, reducing the chances that following a failure, a second disk would fail during the rebuild.

If I had to redo it today, I would have spend the extra dollars on a fourth disk, and gone RAID 10 instead of RAID 5. I wasn't willing at the time to spend an extra $400 on a fourth disk. Sadly QNAP's RAID Migration does not support 5 -> 10 scenarios, so I'd have to do a full backup and restore to migrate (and my current backup lacks the space to also include the ~5 TB on the main NAS that are actually backups from my PCs and servers, so these would have to be lost).