Which RAID for me ?

[JohnnyJazz]

After the recent crash of my NAS that was a reminder that RAID is NOT a backup solution, here I am with a brand new 16TB NAS (4 x 4TB) that I'm getting ready to feed my home entertainment system. One of the first step before uploading my media collection is to chose the RAID mode. The options are :

- JBOD

- Spanning

- RAID 0

- RAID 1

- RAID 5

- RAID 10

Now is the question. What the use of RAID ? It eats up valuable storage space and makes data recovery more complicated in case of system crash. The advantage of RAID are data redundancy and performance improvement. In my case the NAS is used as a media server. If a disk crashes and I've to wait until tomorrow to watch a movie, it's not a tragedy. Performance improvement ????

So what is your opinion ?

[KittenKong]

RAID is fairly pointless for a home media server.

The various flavours of RAID are designed to give fast performance and/or to keep all data available automatically in case of drive failure, with the possibility of building a new drive automatically without any human intervention apart from physically slotting in the new drive. Neither is really applicable to home use where someone is usually around to do things and where the world wont come to an end if you cant access data for a few hours whilst restoring from a backup.

And, as you point out, RAID is never a backup solution. So as you must have a backup as well, why bother with RAID in a domestic situation in the first place?

I used to have RAID set up on my DLink NAS, but then I realised that it was a waste of money and electricity. So I just pulled out the second drive and use it as a backup for the data stored on the single drive in the NAS. OK, I have to connect the second drive manually once a week and run some backup software, but that's no big deal.

Edited November 3, 2015 by KittenKong

[MaeJoMTB]

I also tried raid. Realized fairly quickly it was an easy way to lose ALL your data. Now I have two hard drives with the same data on both in different parts of the house. My personal data (photos) is also stored online with two different clouds.

[ETatBKK]

RAID is an UP-TIME solution, but not a BACKUP solution. weeks ago I encountered a NAS controller failure, all data locked in the HDD RAID set.

as I keep my work data and family archives in the NAS, then multiple data instances is more important than a always-available RAID setup. with the new NAS, I setup my data as follow :

- ORIGINAL first instance data on couple of computers and mobile devices

- 2nd instance data consolidate into the non-RAID NAS

- 3rd instance data ( work data and some critical data only ) upload to cloud

in event of failure, I have at least 2 instances of data and keep things moving.

[thaimite]

RAID 5 can prevent data loss if a single disk fails in an array of disks.. However it is not really suitable for hoe use in its standard format.

I use a free software application called SnapRAID which is designed for people running media server. I have 4 data disks and a parity disk in my array and it has saved my data several times when drives have failed..

Snap raid allows the use of mixed drive capacities and does not use a special data format so disks can be added to the arrary without reformattingand. Even without the software instaled the data is still accessable. It also means that in the unlikely event of simultanious failure of 2 drives, it does not mean you loose all data as you would in a standard RAID 5 setup. However SnapRAID must be run on a regular basis. Of course SnapRAID does have its disadvantages and those interested should do their own research.

Many people like RAID 1 mirroring, but in my opinion, this has no advantage over backups and can even be worse because a corrupted file will be mirrored so there is no recovery whereas a proper backup system should reduce this risk

[Chicog]

I just use a Drobo, does it's own protection.

Run out of a space: Plug in a new drive.

Disk fails: Plug in a new drive.

Don't really even think about it.

If something destroys the whole thing I'd probably have bigger things to worry about.

[JohnnyJazz]

I think we all agree that RAID is of no use.

So JBOD or spanning ?

[ravip]

How about the Synology DiskStation?

[elgordo38]

RAID is an UP-TIME solution, but not a BACKUP solution. weeks ago I encountered a NAS controller failure, all data locked in the HDD RAID set.

as I keep my work data and family archives in the NAS, then multiple data instances is more important than a always-available RAID setup. with the new NAS, I setup my data as follow :

- ORIGINAL first instance data on couple of computers and mobile devices

- 2nd instance data consolidate into the non-RAID NAS

- 3rd instance data ( work data and some critical data only ) upload to cloud

in event of failure, I have at least 2 instances of data and keep things moving.

My friend has a 16T Raid unit and he swears at it. It refuses to talk to him sometimes bypassing one of the drives and he has to reboot it and start over. Pain in the arse from what I can see.

[Lampang2]

raid 5

[phazey]

With 4 drives, use RAID5 - you'll have some decent parity there. Do not use JBOD (Just Bring Old Disks) as it's just spanning.

[hhgz]

"What the use of RAID ?"

​If you do not understand the fundamentals of RAID, trying to assist you in choosing a specific RAID protocol would be useless. Simply, RAID provides a backup solution.

Edited November 5, 2015 by hhgz

[ravip]

"What the use of RAID?"

RAID Made Easy

http://www.pcworld.com/article/194360/raid-made-easy.html

RAID (redundant array of independent disks) definition

http://searchstorage.techtarget.com/definition/RAID

[thaimite]

"What the use of RAID ?"

​If you do not understand the fundamentals of RAID, trying to assist you in choosing a specific RAID protocol would be useless. Simply, RAID provides a backup solution.

WRONG

RAID does NOT provide a backup solution.

RAID 1, 5, 6 provide protectoin against a drive failure in in an array of drives i.e. if a disk of a group of disks fail the data can be recovered. This is NOT the same as a backup which protects against data loss by accidential deletion or major hardware loss . Both RAID and backup are important for critical data.

RAID allows you to contiue workingwith the data until the faulty disks(s) are replaced and the array rebuilt which is often critical for business applications. NOTE RAID 1 and 5 can cope with a single disk in an array failing while RAID 6 can survive 2 simultanious failures.

RAID 0 allows you to create a large disk out of 2 smaller disks but this is not advisable because it means that if EITHER disk fails you lose all your data thus in effect halving your systems reliability

Other RAIDS have other advantages and disadvantages and you can check these out for yourself

With respect to RAID 5 this uses one extra disk to allow the recovery of all data if any single disk fails e.g. In a RAID array of 4 disks you will only have the capacity of 3 disks because of the recovery algorythm. In an array of 6 disk you will have the capacity of 5 disks.

Disadvabtages of a standard RAID are

• All disks have to be the same size and ideally the sane oerformance specifications
• You cannot add extra drives or increase disk capacity without completely reformatting the whole array
• As the data is 'striped' across all cisks if the RAID controller fails you cannot access any of the data.
• The disks get a lot more wear and tear as the array is constantly self checking.

SnapRAID does not have these issues but in the event of failure you are dependent on how recently the RAID was updated. In additoin SnapRAID requires you to recover the data from the failed disk manually before it can be used. For these reasons SnapRAID is most suitable for protecting against data loss in a multimedia collection where the data changes infrequently and is not critical to be available 24/7. This for me is sufficient qnd updating the array takes less than 5 minutes a day, but even though I use it for movies etc as a cheap way of ensuring I can survive a drive failure of which I have had a few, all my critical data is also backed up. either on another device or in the cloud.

So while a RAID array may prevent data loss by a drive failure it is NOT the same as a backup, however if your only concern is hardware failure it may suffice

[innerspace]

How many drives will you have?

2 drives have 2 choices.

Raid 0 high risk max capacity max performance(performance only helps media if disks are bottleneck which is unlikely)

Raid 1 good reliability half capacity gone average (or possibly higher performance)

If 4 drives raid 5 is compromise, better reliability, performance maybe down a touch and lose 25% space.

Raid 1 crazy safe but lose 75% space.

Raid 0 crazy fast max space crazy risk.

Raid 10 fast and fairly safe losing 50% of space.

CPU or network may be bottleneck on performance or required speed may be fast enough anyway so that may not be a priority.

Reliability wise most except 0 Allow 1 disk to fail at least. 5 has increased chance of 2nd disk dying during rebuild losing all data.

While most media is replaceable (hope not family photos) copying 4TB from a backup is a long enough task and redownloading that media collection will takes ages.

Performance space and reliability pick the top 1 or 2 for you and the above answers your question. Different preferences different answer.

And don't forget additional backups too, Raid CAN be a backup but should never be the only one.

[JohnnyJazz]

^^ Thanks thaimite for your very detailed explanation.

But obviously some people didn't understand the question. Let's put in an other way. Do you need RAID for a home media server ? If yes, which one ?

When you buy a WD NAS MyCloud EX4 (4 bays, 4 x 4TB), it comes with RAID 5 setting. So WD believes that RAID is a must and RAID 5 the best option.

I don't agree. I just reformatted my NAS and chose the JBOD option which I believe is more suitable for a home media server. Why ? Let's quote thaimite "RAID allows you to contiue working with the data until the faulty disks(s) are replaced and the array rebuilt which is often critical for business applications" As I said, it's a home media server and if there is a disk failure and I need to wait until tomorrow to watch a movie or enjoy The Beatles' White Album it's not a tragedy. So why wasting 25% of my storage space for a service I don't need ?

Edited November 6, 2015 by JohnnyJazz

[thaimite]

^^ Thanks thaimite for your very detailed explanation.

But obviously some people didn't understand the question. Let's put in an other way. Do you need RAID for a home media server ? If yes, which one ?

When you buy a WD NAS MyCloud EX4 (4 bays, 4 x 4TB), it comes with RAID 5 setting. So WD believes that RAID is a must and RAID 5 the best option.

I don't agree. I just reformatted my NAS and chose the JBOD option which I believe is more suitable for a home media server. Why ? Let's quote thaimite "RAID allows you to contiue working with the data until the faulty disks(s) are replaced and the array rebuilt which is often critical for business applications" As I said, it's a home media server and if there is a disk failure and I need to wait until tomorrow to watch a movie or enjoy The Beatles' White Album it's not a tragedy. So why wasting 25% of my storage space for a service I don't need ?

Please let me clarify.

With a normal RAID you do not have to wait for the RAID array tro be rebuilt before you can use it. however with SnapRAID (which I obviously like but have no other connection with) in exchange for the advanataghes of being able to increase the capacity by adding / replacing disks or being able to access the disks outside the RAID software this is the price you pay.

For example I have an old Buffalo NAS whcih came with 4 of 250GB disks. To increase the capacity I would need to replace all the disks and reformat. With my SnapRAID I have a mixture of 6 drives ranging from 750GB to 2TB and can easily add disks or change the size of any disk without effecting the data. I just need to run the sync command when finished to recreate the parity disk (used for the recovery process which takes several hours although I can read from (but not write to) the other disks in the RAID while this is in progres. NOTE SnapRAID is just a free software that runs on your PC and can be used wih a combination of any disks, internal, USB or network attached)

However with either RAID 5 option you can watch your movie tomorrow. With JOBD unless you have some other form of backup you will need to re-aquire the data bfore you can watch / listen to it ever again. I thnk Chicg's Drobo sounds very similar to SnapRAID but in a dedicated box rather than a software solution

[JohnnyJazz]

However with either RAID 5 option you can watch your movie tomorrow. With JOBD unless you have some other form of backup you will need to re-aquire the data bfore you can watch / listen to it ever again. I thnk Chicg's Drobo sounds very similar to SnapRAID but in a dedicated box rather than a software solution

I'm very disappointed by your answer ;-) I thought we already agreed that RAID WAS NOT a back up solution. So RAID or no RAID I'll need (and I have) a spare copy of all my files. And for the most important ones more than one copy and in more than one location.

Back up rule of three :

• 3 copies of anything you care about - Two isn't enough if it's important.
• 2 different formats - Example: Dropbox+DVDs or Hard Drive+Memory Stick or CD+Crash Plan, or more
• 1 off-site backup - If the house burns down, how will you get your memories back?

[thaimite]

Warning with JOBD.

From what I can see depending on the manifacturers implementation JOBD can eith be a true RAID 0 or a spanning algorythm.

The problem with any form of JOBD is that if ANY drive failes then ALL of your data becomes unavailable. Thus in theory the reliability of your JOBD is 25% of a single drive.

If your JOBD implementation is a RAID 0 implementation then the data wil probably be goine for good, however if it is just a logical spanning of the disks, the chances of getting most of your data back from the remaining drives would be quite good. Personally I would stay well away from RAID 0 or spanning unless I had other forms of backup.

At the very least I advise more research iness you are happy wih the risks.

[thaimite]

However with either RAID 5 option you can watch your movie tomorrow. With JOBD unless you have some other form of backup you will need to re-aquire the data bfore you can watch / listen to it ever again. I thnk Chicg's Drobo sounds very similar to SnapRAID but in a dedicated box rather than a software solution

I'm very disappointed by your answer ;-) I thought we already agreed that RAID WAS NOT a back up solution. So RAID or no RAID I'll need (and I have) a spare copy of all my files. And for the most important ones more than one copy and in more than one location.

Back up rule of three :

• 3 copies of anything you care about - Two isn't enough if it's important.
• 2 different formats - Example: Dropbox+DVDs or Hard Drive+Memory Stick or CD+Crash Plan, or more
• 1 off-site backup - If the house burns down, how will you get your memories back?

Sorry if you misundersttod.

As I clearly stated in an earlier post RAID is NOT a backup solution. Some RAID levels (1, 5, 6)simply provide the abailty to recover data after a single (or double in the case of RAID 6 disk failure. RAID does not provide protection against accidental deletion, or corruption or other forms of data loss.

For many people this is sufficient, and is what I use for my movies and music. I recommend RAID 5 (SnapRAID or dedicated RAID controller) in arrays of 6 disks or less as

the most cost efficient for home use.

However as you correctly state valuable data should be backed up by other means and ideally you should implement multi generations of backup as it may be weeks or even months efore you realise that some bery valuabe file is missing or corrupted. My non-replacable critical data Is backed up to other devices and / or the cloud.

Edited November 6, 2015 by thaimite

[JohnnyJazz]

For many people this is sufficient, and is what I use for my movies and music. I recommend RAID 5 (SnapRAID or dedicated RAID controller) in arrays of 6 disks or less as

the most cost efficient for home use.

So clearly here no misunderstanding but total disagreement.

For demonstration purpose let's say that 1 TB of physical storage cost THB 1,000. So 16 TB will cost me 16,000 THB. With RAID 5 I'll have only 12 TB available for the same price which now makes the TB 33% more expensive. So please explain me how RAID 5 can be the most cost efficient for home use when I've clearly stated (and others have agreed with me) that RAID was of little use in a non professional environment.

[JohnnyJazz]

Warning with JOBD.

From what I can see depending on the manifacturers implementation JOBD can eith be a true RAID 0 or a spanning algorythm.

The problem with any form of JOBD is that if ANY drive failes then ALL of your data becomes unavailable. Thus in theory the reliability of your JOBD is 25% of a single drive.

If your JOBD implementation is a RAID 0 implementation then the data wil probably be goine for good, however if it is just a logical spanning of the disks, the chances of getting most of your data back from the remaining drives would be quite good. Personally I would stay well away from RAID 0 or spanning unless I had other forms of backup.

At the very least I advise more research iness you are happy wih the risks.

Agree with the warning with JBOD, After reformatting my NAS, it just looks like spanning but WD offers the two options so I don't really understand the difference (for WD) , more research are effectively needed.

But what really bothers me is your statement "Personally I would stay well away from RAID 0 or spanning unless I had other forms of backup." What ever RAID you chose you need a back up. And definitively not "an other form of" because RAID is not a back up solution.

Edited November 6, 2015 by JohnnyJazz

[thaimite]

For many people this is sufficient, and is what I use for my movies and music. I recommend RAID 5 (SnapRAID or dedicated RAID controller) in arrays of 6 disks or less as

the most cost efficient for home use.

So clearly here no misunderstanding but total disagreement.

For demonstration purpose let's say that 1 TB of physical storage cost THB 1,000. So 16 TB will cost me 16,000 THB. With RAID 5 I'll have only 12 TB available for the same price which now makes the TB 33% more expensive. So please explain me how RAID 5 can be the most cost efficient for home use when I've clearly stated (and others have agreed with me) that RAID was of little use in a non professional environment.

As stated, for my movies and music which take up many terrabytes I do not want a full backup routine.

I am happy with a RAID 5 which protects me against a disk failure only.

As RAID 5 requires only 1 extra disk in the array (in my case 5 data disks and one called a Parity disk in SnapRAID) I only lose 1/6th of the total capacity.

Note a regular hardware RAID uses data striping acrtoss all discs so does not diferentiate between data and parity disks. but the end result is the same

Thus when a disk fails (as has happened several times) I do not lose any data, but I do understand that should there be a fire or theft or other major disaster in my house I could lose all those media files, but as I consider the risk small, I have decided not to worry about it

So to clarify RAID 5 is the most cost effective RAID solution. However It ONLY provides protection against a disk failure but does not provide protection against other forms of data loss or corruption, which if required needs to be considerered seperately.

[thaimite]

Warning with JOBD.

From what I can see depending on the manifacturers implementation JOBD can eith be a true RAID 0 or a spanning algorythm.

The problem with any form of JOBD is that if ANY drive failes then ALL of your data becomes unavailable. Thus in theory the reliability of your JOBD is 25% of a single drive.

If your JOBD implementation is a RAID 0 implementation then the data wil probably be goine for good, however if it is just a logical spanning of the disks, the chances of getting most of your data back from the remaining drives would be quite good. Personally I would stay well away from RAID 0 or spanning unless I had other forms of backup.

At the very least I advise more research iness you are happy wih the risks.

Agree with the warning with JBOD, After reformatting my NAS, it just looks like spanning but WD offers the two options so I don't really understand the difference (for WD) , more research are effectively needed.

But what really bothers me is your statement "Personally I would stay well away from RAID 0 or spanning unless I had other forms of backup." What ever RAID you chose you need a back up. And definitively not "an other form of" because RAID is not a back up solution.

With RAID 0 or spanning if ANY drive fails you lose ALL your data not just from the one drive that has failed. If you can live with having to juggle data between drives then with nop JOBD or RAID 0 then you only have to recover the data on the one failed disk, and if for some reason your backups are not fully up to date the chances pof losing somthing vital (excluding Murphy's law) is only a 1/4 of I think than with JOBD/ There are options that allow disk spanning without this issue but I have not investigated them or tried them

[CaptHaddock]

RAID 5 can prevent data loss if a single disk fails in an array of disks.. However it is not really suitable for hoe use in its standard format.

I use a free software application called SnapRAID which is designed for people running media server. I have 4 data disks and a parity disk in my array and it has saved my data several times when drives have failed..

Snap raid allows the use of mixed drive capacities and does not use a special data format so disks can be added to the arrary without reformattingand. Even without the software instaled the data is still accessable. It also means that in the unlikely event of simultanious failure of 2 drives, it does not mean you loose all data as you would in a standard RAID 5 setup. However SnapRAID must be run on a regular basis. Of course SnapRAID does have its disadvantages and those interested should do their own research.

Many people like RAID 1 mirroring, but in my opinion, this has no advantage over backups and can even be worse because a corrupted file will be mirrored so there is no recovery whereas a proper backup system should reduce this risk

I recommend RAID 1 for ease of recovery after disk failure. I recently had our RAID 10 configuration fail with 2 out of 4 drives unreadable. I tried to recover it myself with available software without success so I had to give it to a data recovery company here who were able to recover the files partially, but because they did not understand the HFS+ file system used by OSX not all information was recovered. Had the array been configured as RAID 1 I would just have been able to mount the readable disks using a SATA to USB device and get all my files. The only advantage of RAID 10 is improved performance, but that difference is unlikely to matter for home users. Live and learn.

[thaimite]

RAID 5 can prevent data loss if a single disk fails in an array of disks.. However it is not really suitable for hoe use in its standard format.

I use a free software application called SnapRAID which is designed for people running media server. I have 4 data disks and a parity disk in my array and it has saved my data several times when drives have failed..

Snap raid allows the use of mixed drive capacities and does not use a special data format so disks can be added to the arrary without reformattingand. Even without the software instaled the data is still accessable. It also means that in the unlikely event of simultanious failure of 2 drives, it does not mean you loose all data as you would in a standard RAID 5 setup. However SnapRAID must be run on a regular basis. Of course SnapRAID does have its disadvantages and those interested should do their own research.

Many people like RAID 1 mirroring, but in my opinion, this has no advantage over backups and can even be worse because a corrupted file will be mirrored so there is no recovery whereas a proper backup system should reduce this risk

I recommend RAID 1 for ease of recovery after disk failure. I recently had our RAID 10 configuration fail with 2 out of 4 drives unreadable. I tried to recover it myself with available software without success so I had to give it to a data recovery company here who were able to recover the files partially, but because they did not understand the HFS+ file system used by OSX not all information was recovered. Had the array been configured as RAID 1 I would just have been able to mount the readable disks using a SATA to USB device and get all my files. The only advantage of RAID 10 is improved performance, but that difference is unlikely to matter for home users. Live and learn.

Only RAID 6 is designed to cope with multiple disk failures, and when this happens if the faulty disk is replaced the array should be rebuilt automatically (maybe a user command or 2 required to start the proces. As stated above regular hardware RAID arraays use striping where the data is written across all disks and thus is very difficult to recover outside of the array controller.

The important thing when using any RAID array is to replace any faulty disks as soon as possible and rebuild the array.

The software RAID implenentation I have mentioned to many times does allow for the disks to be accessed normally so even if multiple disks fail the data on the others is still available but the data on the failed disks cannot be recovered after multiple suimultanious failures. This is because it does not use striping but just builds the array byy collecting data from the regular disks and saving the recovery information on the 'parity' disk.

[CaptHaddock]

RAID 5 can prevent data loss if a single disk fails in an array of disks.. However it is not really suitable for hoe use in its standard format.

I use a free software application called SnapRAID which is designed for people running media server. I have 4 data disks and a parity disk in my array and it has saved my data several times when drives have failed..

Snap raid allows the use of mixed drive capacities and does not use a special data format so disks can be added to the arrary without reformattingand. Even without the software instaled the data is still accessable. It also means that in the unlikely event of simultanious failure of 2 drives, it does not mean you loose all data as you would in a standard RAID 5 setup. However SnapRAID must be run on a regular basis. Of course SnapRAID does have its disadvantages and those interested should do their own research.

Many people like RAID 1 mirroring, but in my opinion, this has no advantage over backups and can even be worse because a corrupted file will be mirrored so there is no recovery whereas a proper backup system should reduce this risk

I recommend RAID 1 for ease of recovery after disk failure. I recently had our RAID 10 configuration fail with 2 out of 4 drives unreadable. I tried to recover it myself with available software without success so I had to give it to a data recovery company here who were able to recover the files partially, but because they did not understand the HFS+ file system used by OSX not all information was recovered. Had the array been configured as RAID 1 I would just have been able to mount the readable disks using a SATA to USB device and get all my files. The only advantage of RAID 10 is improved performance, but that difference is unlikely to matter for home users. Live and learn.

Only RAID 6 is designed to cope with multiple disk failures, and when this happens if the faulty disk is replaced the array should be rebuilt automatically (maybe a user command or 2 required to start the proces. As stated above regular hardware RAID arraays use striping where the data is written across all disks and thus is very difficult to recover outside of the array controller.

The important thing when using any RAID array is to replace any faulty disks as soon as possible and rebuild the array.

The software RAID implenentation I have mentioned to many times does allow for the disks to be accessed normally so even if multiple disks fail the data on the others is still available but the data on the failed disks cannot be recovered after multiple suimultanious failures. This is because it does not use striping but just builds the array byy collecting data from the regular disks and saving the recovery information on the 'parity' disk.

RAID 1 is mirrored, but not striped. My configuration was two RAID 10 volumes, each with two mirrored and striped disks. So, even though I was not able to access two of the disks the data from the two I could read could have been recovered simply by mounting the disks if they had been only mirrored and not striped.

In the event the data recovery company was able to read all the disks by using hardware recovery tools not available to me.

[innerspace]

If cost is the sole concern go with jbod or raid 0 and maximise cost to capacity ratio.

While raid is not essential in a home or media environment that does not mean it is worthless.

If you value any of data, inconvenience, downtime or media redownloading time then consider raid, if not risk it and go cheap.

You have all the info you need in this thread already, stop reading people's personal preferences in different situations as disagreements, virtually all posts in this thread are valid.

So read, digest, apply to your own situation and question is answered.

Personally I use synology raid (hybrid raid 5 style like that snap raid mentioned) since downtime and inconvenience are valuable to me, time is money. My important bits are backed up, double or triple, my media isn't, I can redownload movies but would prefer not to given the size of it.