I have 5 HDDs. Should I keep one as a spare?

[twentyseven]

I have five 2TB drives. What is your opinion on how I should configure?

1. Should I just put all 5 in my FreeNAS as an array?
2. Should I put 4 in the NAS and keep one as a spare for when one fails?
3. Any other suggested configurations?

I definitely do not need the total storage for either case at this point.
Thanks in advance for any opinions.

 

[joeschmuck]

It depends on what configuration you want for your pool. Do you want a RAIDZ1 or RAIDZ2 and how much storage space do you want. Reworded, how safe do you want your data and double the storage space that you think you need.

Here is a link to a RAID calculator http://www.servethehome.com/raid-calculator/

In my opinion if your are using the NAS for computer backups and a media server, use a RAIDZ1 configuration.
For a RAIDZ1 with four 2TB drives you have 5.5TB of usable storage.
For a RAIDZ1 with five 2TB drives you have 7.3TB of usable storage.

If you are going to store important data on your NAS and you would rather not ever desire to reinstall your data then having a 2 drive fault tolerance is more important so a RAIDZ2 makes more sense to me. This is what most people eventually run.

For a RAIDZ2 with five 2TB drives you would have 5.5TB of usable storage.

So first figure out how much storage you need and the protection level.

For myself I have six 2TB drives in a RAIDZ2 configuration. All my drives have a 3 year warranty so I'm good for drives until late 2015 and early 2016. I will buy a spare 2TB drive a few months before my first drive goes out of warranty. I do not have a spare 2TB driver on hand because I have no problems submitting an RMA where the replacement drive is shipped immediately and when I get that drive, I return the failed drive. You have to give up your credit card info but that is fine by me. And I should be able to run my system until the new drive arrives. If I have a second drive failure before then, well I'll shut the system down and wait for the drive to arrive. And I always maintain a separate backup of all important data. Other data like movies, well if I loose them I know I won't be happy because it took a long time to rip them but I won't loose sleep over it either.

I hope this helps.

 

[twentyseven]

Wow joeschmuck, this is incredibly helpful. I appreciate your time and reply.

A follow-up question - you mention "other data like movies". (I feel the same way about losing data like that - no super biggie). Do you keep your movies in the RAIDZ2 setup that you mentioned, or do you have another storage box or non-raided storage for stuff like that? I also wonder if I could add a couple spare 1TB drives to the FreeNAS and create a separate JBOD volume for the movies, etc.

 

[joeschmuck]

Yes, all my data is on the RAIDZ2. You could easily add either a single drive or a few drives to create another pool separate from the pool you want important data on. The problem here might be a hardware limitation such as not enough SATA ports to connect your hard drives. I have around 150 movies (.mkv format at 720p) which take up just over 800GB of storage space. I honestly could delete 100 of those movies because the odds that I watch them again within the next year is low and I recently subscribed to Netflix so most of those movies are already available by those means.

Let's get back to hardware limitations... If you use four 2TB drives for a RAIDZ2 (3.6TB usable space) and then two 1TB drives for a RAIDZ1 (900GB usable space) for movies well you have used all your SATA ports on a typical motherboard. If you just go with five 2TB drives in a RAIDZ2 (5.5TB usable space) then you have increased data security, more storage, and save a little power because you are running only 5 drives vice 6 drives.

As I said in my previous posting, most people end up running RAIDZ2 once they have played with the system for a few months. Save yourself the hassle and just adopt it up front, you will thank me for that advice. The only reason people typically choose RAIDZ1 is because they don't want to spend money on so many hard drives. Over a period of months they play with FreeNAS and realize they can afford another hard drive and eventually adopt RAIDZ2. It sucks to lay out all that money at once but it sounds like you already have 5 drives on hand.

And I know you didn't ask this at all but please ensure that you understand, you must run ECC RAM with a ZFS file system if you want to protect your data. 8GB of RAM is the minimum for good performance, 16GB I would say in the maximum and anything more is just overkill for a home user.

Sorry, I got a little long winded.

 

[ZFS Noob]

I'd see the choice a little differently. The odds of a RAIDZ1 array failing while resilvering are high enough that I just won't use it with modern drives and their capacities. So for me, the choice would be between:

• RAIDZ2 for capacity, as listed above
• RAID10 - two mirrored vdevs striped together.

By default I go to RAID10, but I'm probably doing different things in my environment than you are. RAID10 gives higher iops and replacing a failed drive won't have the same performance implications that parity RAID will, but there's a cost in available space, and you'd be stuck with one drive, either as a hot or cold spare.
The choice really depends on what you're trying to do.

 

[twentyseven]

Thanks for the advice everyone. I ended up with a Z2 configuration on 5x2TB drives. Next step is to repurpose my old ReadyNAS device with 4x1TB as a backup unit.

 

[joeschmuck]

That is a good idea. I use an old NAS with two 2TB drives as a backup of all my valuable information on my FreeNAS. The old NAS is slow as dirt but I only update changed files and it sleeps all day long until every night there is a very quick copy of the changed files. I have a lot of movies on my FreeNAS machine, I do not place those on my old NAS. Those can be replaced but personal photos I place on the NAS. Of course I actually periodically create a new set of DVDs of my photos and all financial data. You never know when an electrical storm will take out all your data, or that is how I see it.

 

[twentyseven]

I configured my backup ReadyNAS as RAID0. I don't think I need any sort of redundancy on the backup since holistically the primary and backup are redundant with each other.

Here is my logic on not RAIDing the backup,

• Primary (FreeNAS) is redundant (Z2) and the backup would essentially be a mirror. (in essence, yet another level of redundancy)
• Backup (ReadyNAS) HDDs health is monitored through Frontview with alerts . If problems arise, I should theoretically know right away through email.
• If a problem occurs in the backup and I lose some of the data, I can recreate a backup from the primary once the backup is fixed - which will temporarily leave me as vulnerable as I am in today's everyday scenario - i.e. one RAIDed configuration.
• The chances of having a fault in the primary and the backup that results in data loss should statistically be remote

What are your thoughts about RAID (or lack thereof) on the backup?

 

[joeschmuck]

I think your backup solution is fine. It's just like mine except I use two individual drives as separate drives. I plan on both servers never going down at the same time. And important info is on DVD just in case they do.

 

[twentyseven]

Thanks again for the info joeschmuck. Are you just using rsync, using the crashplan plugin, or some other method for your backups? I will eventually be putting my BackupNAS offsite so I will want some sort of incremental "changes only" once the initial backup is done, but I am having problems deciding which backup to use and can't seem to find any discussions where people weigh the pros and cons.

 

[joeschmuck]

I have nothing fancy for backups of my NAS files, I'm using SyncToys for Windoze. I'd like to end up using rsync in the future but haven't made my way there yet. I also do a manual DVD creation periodically to ensure my valuable data is not lost during a catastrophic error.

As for pros and cons of the different types, you need to look harder. I know there have been discussions on the methods you have discussed. If you find one that is easy to incorporate and does what you need, then I'd use that one. You can also just test out some for yourself to see what works better for your system.