RAID levels - best one ?

Sootchucker

Sootchucker

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Might not get a lot of responses to this, but I'm soon looking to upgrade my NAS to a new 4 bay unit with 4 off 8tb discs.

For the last 10 years or so, using either Netgear or later on QNAP NAS's, I've always used RAID 5. This gives me a total of 3 combined drive capacity with one drive for parity so one drive can fail and be be replaced without destroying the RAID array.

However, as all my movies are also on the NAS (over 1000 of them) and it's taken me years to purchase them / rip personal copies from DVD's and Blu-ray etc, and I'd rather not got through that again. So I'm now wondering if Raid 5 is the best of go for another ?

My options (I think) are

RAID 5 - Stick with this, This will get me approx. 24TB of storage, but only one drive being able to fail before the RIAD array fails.

RAID 6 - This will give me an approx. 16TB of storage space with 2 drives being used for disc protection.

RAID 10 - This will also give me approx. 16TB of storage but this combines Mirroring with Striping so gives les storage space than RAID 5 but gives faster read / writes and full redundancy.

I'm leaning towards RAID 10, but would appreciated thoughts please Are there any advantages / disadvantages between RAID 6 and 10 that I haven't considered ?
 
Why not raid 1 out of curiosity? Are you trying to keep it as one volume/drive?
 
I know RAID 1 mirrors one drive to the remaining 3 and so gives excellent levels of redundancy, but I need at least 12tb of space, so going. Raid 1 with 8 tb discs only gives me 8tb. Even going 10tb discs only gives me 10tb space. 14tb and upwards disc are currently hideously expensive.

Yes, it will be one volume for all the movies.
 
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Raid 1 could be setup in pairs, so drive 1 and 2 are mirrored, and 3 and 4 are mirrored. This would give you the 16tb of space.

It removes the striping element, which comes at the expense of some write speed.
 
Won't the advantages of striping the drives be negated by the network interface efficiency? I can see the point of striping if it's within a machine with direct bus access but once you're transferring data over a network at 1gb max then striping the drives won't make much difference as you're only likely to see a transfer rate around 600-800mb/s?
 
Are you RAIDing for capacity or redundancy?

With only 4 Drives, I've personally gone R5. R6 is basically R5+1 "extra" spare when one fails. But the issue is you have is only have 4 drives. So R5 is n+1 (3+1), R6 is n+2 = 2 drives + two "spare", better than mirroring for redundancy as you can lose ANY two drives.
 
With four large drives RAID 10 is the best choice. RAID 6 has too high an overhead and using any RAID with a parity drive (i.e. 5 or 6) with the minumum number of drives is a disaster waiting to happen. Current best practice is not to use RAID 5 or 6 with large drives as the chance of losing another drive during any RAID rebuild is too high.

As you've already been told, your definition of RAID 1 is completely wrong. What you described could possibly be defined as RAID 11. ;)
 
RAID 10 will give you very specific redundancy, if you lost 2 disks you may lose your data depending what disks failed.

RAID 6 has better redundancy but does not perform as well, RAID 5 has less redundancy but you could assign Disk 4 as a hot-spare, this would still require rebuild time upon a failure but it would be an extra step.

FWIW, Have you considered purchasing a 5th disk but keeping it aside, so if you popped a disk you have a spare to immediately start the rebuild process?

In any case, as good as RAID is, its no substitute for a backup strategy, all it takes is RAID controller malfunction or a NAS software problem and suddenly your RAID set is toast, regardless of the level.
 
What I do say the minute in my NAS is I have 2 8tb drives in a RAID 1, I also have a 3tb drive that is a backup for critical data, such as photos and documents. The rest of the data on the RAID drives such as movies and music doesn't get backed up.
This way the 3tb backup drive is very unlikely to die at the same time as the other drivers due to it only powering up twice a week for a backup.
I actually also keep a copy of photos on my main pc, which auto syncs to the NAS.
 
Have you looked at Synology SHR ??

nascompares.com

What is SHR? And what is the difference between Synology Hybrid RAID and Ordinary RAID?

What is the difference between SHR and RAID? Synology Hybrid RAID or SHR, has been around for quite a while now, and though it has not make the big impact that Synology NAS’ Btrfs file system has, it is still an increasing popular choice for many when it comes to protecting their hardware and their
nascompares.com nascompares.com

One big advantage is that you can mix and match drives (don't need identical drives), so in the future if you got a drive failure you could substitute a different drive size/type in

My NAS has 3 drives in an SHR configuration and an additional further drive, which holds some duplicated files from my PC/Laptop - ones that are not critical and my looping CCTV feed
 
A colleague highly recommends the Buffalo TerraStation. What are peoples opinion?
 
dcash29 said:
A colleague highly recommends the Buffalo TerraStation. What are peoples opinion?
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No, kill it with fire!!! Have witnessed quite a few failures of these over the years. Unreliable and slow.

For me, it’s Synology as a first choice, QNAP second, nothing else considered
 
I have just sold my Qnap and bought a Asustor NAS, and to be honest it really is a good bit of kit, every bit as good as the Qnap was as regards apps, although I do not use many of them. Yes Synology and Qnap are the top two dogs but do not discount the Asustor as an alternative. Mine is setup as raid 5 which I think gives me a bit of safety and speed at the same time as having maximum storage.
 
dcash29 said:
A colleague highly recommends the Buffalo TerraStation. What are peoples opinion?
Click to expand...
I think Neil was a bit generous towards it. The only makes worth considering are Asustor, QNAP & Synology. Synology has the halo factor but the other two tend to be ahead in terms of included technology like LAN ports faster than 1Gb and M.2 cache slots.
 
Reason I chose Asustor over the others was you just get more for your money because they aren't the market leaders.
5304T I got for the 2.5GbE, and it had a faster processor than the same priced Synology and Qnap.
 
Snapsh0t said:
Synology has the halo factor but the other two tend to be ahead in terms of included technology like LAN ports faster than 1Gb and M.2 cache slots.
Click to expand...

Synology do this too, or do you mean the more domestic appliances? We’ve got some 10Gbps appliances with M2’s in our server room for non-critical archives but they are the higher-end models tbh
 
Just been reading up on Raid 10 and it seems it too has it's limitations. Taking a 4 disc array as an example, as mentioned above it basically creates mirrored pairs of discs (which is great for R/W speeds). Each of the pair of discs is mirrored across to the other pair. For 4 off 8tb drives installed, the actual available storage would be 16tb approx. (i.e. half of the total capacity of the discs installed).

If one disc in the mirror pair fails, then it can be replaced and it's mirrored "clone" can rebuild it. So as long as one disk in each mirrored pair is functional, data can be retrieved.

However If two disks in the same mirrored pair fail, all data will be lost because there is no parity in the striped sets, meaning you lose everything.

It seems the more I look into it, the more it seems that all RAID arrays come with pros and cons,

I think I'll stick with RAID 5 but I do like the idea mentioned above of buying a 5th disc (exactly the same type and size) as the breakdown spare so that if a drive ever does fail I would then have an immediate new disc to pop in straight away. Then if that disc is used, immediately buy another spare.

Also, again as rightly mentioned above a NAS is not a backup, so in addition I've ordered a 14tb WD My book and that will be my backup (which Ill update each month), then keep in our fireproof safe if the worst happens.

Thanks for all the comments guys, it's been really interesting.
 
Sootchucker said:
owever If two disks in the same mirrored pair fail, all data will be lost because there is no parity in the striped sets, meaning you lose everything.
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That’s what I was referring to in my earlier comment, IMO either RAID5 it with a hot-spare or RAID5 the entire 4 disk set and maybe have a disk stored on a shelf for a failure scenario.

Or just RAID5 the entire set and make sure you’re backups are sound (this is what I’d do for non-critical data).

Neilc28 said:
RAID 10 will give you very specific redundancy, if you lost 2 disks you may lose your data depending what disks failed.
Click to expand...
 
On a second question (if I may be indulged a segway).

My current QNAP NAS is currently connected to my network via a single gigabit ethernet cable to my unmanaged switch, to which other peripherals are connected to (PC, TV, Apple TV etc).My Virgin router is in modem mode and serves to a Netgear Nighthawk R7800 Wi-Fi Router. I've been reading up on Link Aggregation (port trunking) by connecting more than one of the NAS's Lan ports (it has 4) to the switch and enabling port trunking on the NAS. However, am I right in assuming I would need to replace my unmanaged switch with a managed one to get this to work. Also what would the real world benefits (if any) be as the rest of my system is only gigabyte ethernet and my PC at home has only one Lan port. Would I still get an increase in Read / Writes to the NAS or not ?

Secondly, I've seen a lot of newer NAS's come with 2.5GBe or 10GBe network adaptors. If I purchased one of these units, what else would I need to replace to reap any benefits please ?
 
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Sootchucker said:
On a second question (if I may be indulged a segway).

My current QNAP NAS is currently connected to my network via a single gigabit ethernet cable to my unmanaged switch, to which other peripherals are connected to (PC, TV, Apple TV etc).My Virgin router is in modem mode and serves to a Netgear Nighthawk R7800 Wi-Fi Router. I've been reading up on Link Aggregation (port trunking) by connecting more than one of the NAS's Lan ports (it has 4) to the switch and enabling port trunking on the NAS. However, am I right in assuming I would need to replace my unmanaged switch with a managed one to get this to work. Also what would the real world benefits (if any) be as the rest of my system is only gigabyte ethernet and my PC at home has only one Lan port. Would I still get an increase in Read / Writes to the NAS or not ?

Secondly, I've seen a mot of newer NAS's come with 2.5GBe or 10GBe network adaptors. If I purchased one of these units, what else would I need to replace to reap any benefits please ?
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For Link Aggregation you will indeed need a managed switch, and LAG really comes into its own when you have multiple users pulling from the NAS, any single transaction will not saturate any more than 1 link.

unless you were in a situation whereby your client machine had a LAG config with multiple NIC’s or a 2.5/5/10Gbps connection AND you were reading/writing data in 2 different transactions you wouldn’t see a difference. So the overall throughput could be 2Gbps from the NAS but you would only see that by reading/writing 2 different files or transactions simultaneously.

there are vendor specific variants which use a form of channel-bonding which does increase the speed however this is non-standard and has very specific requirements
 
Sorry, having just re-read my comment for the 5th time I may be causing more confusion! Happy to help with any queries though :)
 
Thank Neil, seems you know your networking.

Yes to be clear, it will really only be one user (me) writing to the NAS at a time, when my wife uses our home PC's it's only ever to surf the web really. Basically as my Movies files are between 5-8gb in size each, I just wanted to know if there was a quicker way of transferring them across rather than the 75-95mb/sec I'm currently getting via my current ethernet setup.

I've also noticed that some of the more advanced QNAP NAS's (eg. the TVR-472XT) come with Thunderbolt 3 on board. Would there be anyway of utilizing that connection between the NAS and the PC (assuming I fitted the PC with a thunderbolt 3 card), so get quicker writes onto the NAS or does the speed of the HDD's become a bottleneck ?
 
I would think the speed bottleneck is going to be the disk and RAID overhead more than anything network related assuming you’re wired. RAID10 will most likely yield some improvement but disk type, cache and platter speed also play a crucial part in this.

As an example, Western Digital do their ‘Red’ disks which are designed for NAS’s, however they also 5400 and 7200rpm versions of these, which I’ve noted previously to make quite a difference. Seagate also have their own versions (Skyhawk etc...), as noted above the caching options on a NAS such as DDR or M2 capabilities can also have a massive effect but this is mainly for burst performance rather than sustained, it would probably work well for your scenario but the benefits were negligible for us.

As is always the case, the performance difference would be measured in seconds not minutes, and having come across this dilemma at home I simply opted to put up with the current speed (~90mb/s), SSD’s were too costly and the cost to upgrade my Synology to a later version which supported advanced caching was just too much to justify.

TBH I’m not too familiar with TB3 connectivity for storage, I’ve heard some good things about TB3 arrays but they are DAS units and not the hybrid type you’ve mentioned, the bottleneck of the controller and disks will still be there though.

And thanks for the compliment, I’m an infrastructure engineer and have been for many years (20yrs+) so always happy to dispense some advice whenever it’s asked for!
 
To put it a better way, a link aggregated connection is much like a motorway, you can have 3 cars going 70mph simultaneously if lined up across the lanes, but you don’t get the combined speed of 210mph
 
To the OP.

Are you using your NAS for redundancy or backup or both.

The reason I mention this is:

1. drives are cheap
2. Loss of data is a pain.

Another way of thinking is to not RAID.

Buy 4 x 8Tb drives. copy all the data onto 2 of them & remove them from the machine.
Put them in another location - mine are in a peli case in my shed at the bottom of my garden.
Use the other 2 8Tb's as normal until full then buy some more drives to fit in.
Once a month copy the 'new' data off the NAS onto the 'shed drives.

That then gives you backup & redundancy.
 
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