Need Advice: 6TB Raid 5 or Single 6TB HDD?

iammachine

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Apr 3, 2016
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I've been using a Seagate 3TB HDD as a storage drive in my desktop but the other night it started making a weird high pitched sound so I need to replace it. I'd also like to add more storage because I'm using my desktop as a plex server to stream stuff to my TV and ipad so I'm going to upgrade to 6TB of storage.

I’m planning on going with the WD Red drives because they’re supposed to be very quiet and can run 24/7 reliably since their meant for a NAS. I’m torn between either buying 3 x WD Red 3TB drives and setting them up as a Raid 5 for 6Tb of storage or just buying 1 WD Red 6TB drive. Here’s a list of pros and cons as I see it

Raid Pros
-Potentially faster drive performance
-Raid 5 offers protection against drive failure

Raid Cons
-Cost is higher ($320)
-using three drives might create more noise than I want (I want my machine to be as quiet as possible)

Single Drive Pros
-Cheaper ($240)
-easier (no raid setup)

Single Drive Cons
-Slower than a Raid but for storage maybe it doesn’t matter
-No backup if the drive fails

The biggest variable here is I’ve never set up a Raid, so I don’t really have a sense of the just how much faster or reliable it would be. If I’m getting marginal gains in speed than I’d rather save the cash and just have the single drive. Any opinions/advice would be really helpful, thanks in advance!
 

aparnell572

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Mar 30, 2016
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raid 1 or 5 allows for redundancy and security, how big of a concern is that for you? The noise will depend a lot on the hdd you buy. Raid 5 in specific for 3 drives or more will give redundancy as well as better performance then a single drive. I can't remember at the moment the exact steps to set up a raid 5 but you'll want to set up hardware raid for the best results. Does that answer any of your questions?
 
I am presuming that you do NOT plan a true hardware RAID system. Let me outline what that means.

Doing any RAID (the are all different!) requires extra processing of the data moving both to and from the drives. This means using a processor, some memory, and some software stored permanently in a PROM chip of some design. There are basically three ways to achieve this.

The simplest is the "built-in RAID" of a mobo. The software is already in the BIOS chip on the mobo. It is executed by the computer's main CPU chip, and it uses some of the main RAM for its work. It uses the HDD controller chips already on the mobo. The advantage its cheap cost (you only have to buy extra HDD units); the disadvantage is that this is "software RAID" which consumes processor time and RAM resources, and thus actually can slow down some processing.

The next is a class of simpler (and cheaper) RAID add-on cards that carry their own software BIOS chip, their own HDD controller chips, and a little RAM for buffer use, but have no processor of their own. Such cards have a lot of the work done by the computer's main CPU and using some main RAM resources. This is STILL "software RAID". Advantages include providing more ports to connect additional HDD units, but you cannot mix RAID card ports and main mobo ports in the RAID array - ALL the HDD's in a RAID array managed by such a board must be connected to that board's ports. It also off-loads some of the work from the mobo, notably the control of the HDD's.

An add-on board also addresses another issue for any RAID system. There is NO standard way to do RAID, so each hardware and software maker may have a slightly different way. The result is that a set of HDD's containing data written by one RAID system may NOT be readable if you connect them to a different system. This becomes an issue when your RAID hardware fails and must be replaced. If you were using a "built-in RAID" system on your failed mobo, getting a new mobo that CAN handle your HDDs from the old RAID system might be tricky. (However, there are a few makers of mobo controller chips and BIOS software who have committed to keeping their RAID systems unchanged over several generations, so you can buy a new mobo that uses the same company's controller chips and it should work. I did this and it did work.) Instead if you use an add-on card for your RAID system and it fails, it is very likely that you can buy a replacement card from that same maker (with some advice from them) and it will work with your old drives - just be sure you buy a well-known brand in the first place!

The third way is a more advanced add-on card that carries its own processor, BIOS chip, RAM and HDD controller. This is true "Hardware RAID". The main computer simply hands over data destined for the storage system to the add-on card, just like it would hand the data to a mobo HDD controller chip using a single drive unit. The card's processor, software and RAM are used for all the work involved in the RAID system. Since this is an add-on card, the argument about replacement of a failed card with another from the same maker applies here, too. But the big advantage is that the card off-loads work from the main mobo processor system, and even may be more efficient in doing the work because the processor and software are dedicated and specially designed for this one purpose. Advantages include probable faster performance and ease of replacement; disadvantage is the higher cost of the add-on card because it contains a lot more resources.

So with that background, back to Pros and Cons. Regarding performance, most software RAID5 systems may NOT be faster than a single drive. The advantages of distributing data over several units are offset by the additional work that must be done by the main processor and RAM. This applies both to mobo "built-in RAID" and to cheaper add-on software RAID cards. aparenll572 was quite correct to point out that you would need a true hardware RAID system to expect a performance boost.

Protection against drive failure is a more tricky subject. It is true that a RAID5 system can recover from failure of ONE HDD unit in the array. It can continue to operate, although more slowly, while that drive is missing or failed, and it can do the work necessary to restore the entire RAID array to normal behavior after the failed unit is replaced. It's still not perfect. I experienced a bad RAID5 failure in a company I worked for - IT was not my job, fortunately. First problem was that the HDD replacement units were not available locally, and had to be flown in. THEN they discovered that TWO drive units had failed and it could not restore itself! They had to replace the two drives, build a new empty RAID5 array, and restore all their data from proper backups. They HAD those backups. This IT department was run professionally and had daily backups on site AND off-site. After the failed units were replaced, it still took 3½ days to fully restore from backups while the system was providing services to all users. By the way, RAID6 which uses more drives for the same capacity, and requires more processing work, CAN recover from the simultaneous failure of two drive units.

RAID1 is a much simpler "self-repair" system because all it does it use two drives to make two copies of the same data at the same time - it's called a mirror system. It is well suited to operations where no downtime can be tolerated and the system must keep operating nearly normally when one drive fails, until downtime can be scheduled for repairs. I use this in a Point-of-Sale system in a small retail store we run - any failure can be handled after the store closes for the day. Some people try to treat this (and RAID5) as an "automatic backup system", but it is NOT.

A proper backup system can guard against data loss by many events. The data should be copied to a separate set of storage hardware which is then disconnected from the main system to avoid corruption from malware or electrical mishaps. Those devices then should be stored off-site in a safe place to protect from fire, flood, criminals, etc. Most often the backup software system used makes a full backup of everything first, then makes only incremental backups - that is, back up only what has been CHANGED since the last backup. However, this means that to do a full restore you must start from the original full backup and then restore all the incremental changes. Since that could become a long process, from time to time the process is re-stared at the full backup stage. When that is done, the complete older set of backups is still preserved in case some very old version of the data becomes necessary.

As you can see, proper backup protection cannot be done with a RAID system of any kind that is solely inside your computer. That cannot protect you from many types of threats.

This leads us to a real concern for today's systems, and yours is a good example. Hard drive capacities now are HUGE compared to not very long ago. Whereas at one time tape systems were used to back up HDD's, now those systems just are not big enough. These days the medium for backing up data from a big storage system usually is just big hard drives. Even backing up to a "cloud service" means putting your data on someone else's large drive array system. So, while going to large HDD's or to RAID5 systems can give you increased data storage capacity and MAYBE performance speed, you also need to consider how to protect against data loss. RAID5 or RAID1 can give you only part of the protection you need. Full protection requires a real backup system, and unfortunately that also costs money. So one possible path for you is to go with a single 6TB drive in your computer PLUS one or more external drive units to be used as backup media, plus some decent backup software. The system should be able to preserve off-site and disconnected both the most recent and a few old versions of your data. You might be able to do this for a cost similar to a good RAID5 system, but giving you much better data loss protection.
 

iammachine

Commendable
Apr 3, 2016
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Ok wow, that was a TON of detail, thank you very much Paperdoc. Yes I was planning to do a software RAID only, but now I think I'll just go with the single drive and keep it simple
 
Glad to help, and thanks for Best Solution. I often think that too many people plunge into RAID without understanding what is involved. To do RAID of most forms well and be able to deal with its quirks and problems requires that you learn a lot. And sometimes you learn enough to realize it may not be worth the trouble.
 

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