Hard Drive Requirements

[blue1248]

Hello community

I am still researching my build, and I have most of it in place but I have a really noob (and probably silly) questions on Hard Drive requirements.

I haven't come across an answer to this question...
Do all hard drives need to be the same capacity (but if they are different they will default to the smallest drive)
or
Can they be a mixed assortment of capacity which utilises their capacity to the fullest

In my defence, before I settled on FreeNAS I did a lot of reading on other competitor systems and am suffering from a bit of info overload.

Thanks

 

[Spearfoot]

Welcome to the forum!

The answer to your question is: It Depends!

You can mix drives of various sizes in a RAIDZ array, but, as you pointed out, ZFS will only utilize each drive as though it were the size of the smallest drive in the array. So, 5 x 4TB drives and a single 1TB drive configured in a 6-drive RAIDZ2 vdev, will give you the same space as 6 x 1TB drives - lots of wasted space!

But... you can use drives of differing sizes in matching mirrors and lose less space.

For example: suppose you have 4 x 2TB drives and 2 x 4TB drives. You could create a pool made up of 3 mirrored vdevs (2x2TB, 2x2TB, and 2x4TB) and not lose any capacity at all. The only downside is that mirrors are a little less 'safe' then RAIDZ2 or RAIDZ3 when it comes to redundancy.

Hope this helps answer your question.

Good luck!

 

[blue1248]

Hello Spearfoot and thank you for the reply

Yes your response answers my question.

My requirements are this...

I run a small business from home. Documents and associated data around 30GB (access every other day)
Family Photos (TIFF, RAW, JPEG)- 300GB- (infrequent access)
Music (FLAC, MP3, WAV) 180GB- (daily access)
Movies (DVD, BluRay) - 9TB (daily access)

I wanted to re-use my existing drives, but all recommendations on this site point to using new NAS grade disks. So I will go with that.

I am planning on using RAIDZ which, as I understand, is similar to RAID5 and will give me Parity and Striping. I would then purchase 4x6TB WD RED which gives me roughly 18TB of storage - plenty of capacity for the foreseeable future.

Once all the data is copied across to the storage pool, there will be little write activity, but lots of read (movies).

Is this the most optimal setup regarding storage for my needs?

 

[Spearfoot]

The only problem with your proposed setup is that RAIDZ1 isn't recommended for 'large' drives (>1TB) and you're using very large drives.

Search the forum and/or Google "RAID5 is dead" for details... But in brief: if you lose a disk with RAIDZ1 you risk losing all of your data if a URE (unrecoverable read error) occurs during the re-silvering process when you replace the failed drive, and the larger the drives, the more likely this will happen.

You may find the risk acceptable, but we want you to understand the issue. Many people use 5 or 6 disks in a RAIDZ2 configuration to avoid this risk.

 

[Spearfoot]

Also, it isn't absolutely necessary to use NAS or Enterprise-class drives, though it certainly is a good idea.

I've got 4 WDC 'Green' drives - definitely not recommended devices! - in my secondary FreeNAS system and they plug along just fine. One of them has been in service over 40,000 hours.

Why don't you list the drives you have on-hand? Perhaps we could figure out a configuration using them, to get you started.

 

[nojohnny101]

I'll just add to the excellent info already provided by @Spearfoot and say if I was in your situation, I would use the current drives you already have as long as it doesn't negatively impact your space as far as having a bunch of drives of varying sizes. NAS drives are certainly not a must, we just recommend them if buying new.

Once your new pool is setup with your old drives (in a minimum of raidz2 I hope!) then as they bite the dust, you can replace them with NAS quality drives. Also keep in mind that in order to use your old drives, you'll have to find a way to offload all of your data in order to wipe the drives and create a new pool. This can be accomplished any way you see if and includes but is not limited to: borrowing space from a friend, buying cheap USB external drives to hold data temporarily, etc.

Good luck!

 

[blue1248]

Oh, I missed that RAIDZ1 issue. So then I will implement the RAIDZ2.

I have the following hard drives...
2 x Seagate 3TB- ST3000DM001 - purchased Jan2014
1 x WD Blue 4TB- WD40EZRZ - purchased May2016
1 x WD 4TB My Book external - purchased circa 2012 (I can convert this to a backup drive)

I currently have about 1.2TB available, so I will need to purchase a new drive anyway to increase capacity. This is why I was thinking of the 6TB drives.

 

[Stux]

I'd recommend 6x4TB rather than 4x6TB.

About the same cost and gets you 16TB with dual disk redundancy.

It should be okay to use your pair of 3TB Drives and your 4TB drives in a mirror and would get you 7TB. You could then add another mirror of say 2 6TB drives at any time. Or replace the 3s etc

 

[blue1248]

Thanks nojohnny101. Yes I will use RaidZ2

Thanks Stux. Ok there is a lot more flexibility here than I originally understood.

---- Edit---

Since asking my original question I came across this document : https://dl.dropboxusercontent.com/u/57989017/9.10/FreeNAS Guide 9.10.pptx.zip - Slideshow explaining VDev, zpool, ZIL and L2ARC for noobs. (not sure why I didn't see this earlier)

It has answered my subsequent questions (and my original ones too).

Thank you Spearfoot, nojohnny101 and Stux for your help and apologies for duplicated questions.

 

[Robert Trevellyan]

ST3000DM001

Unfortunately, this model is known for sudden, early failures.

 

[blue1248]

Thanks for the heads-up Robert. They have just turned 3 years old so, as I understand, their chances of failure will continue to increase.

 

[Mr_N]

how much use have they had in those 3 yrs? what does the smart data say?
if you're going to put anything on them you dont wanna lose, recycle them and get a few 4TB drives instead...

 

[blue1248]

Hello Mr_N

I can't give an exact figure, but they do get used daily. Those 2x3TB drives hold Movies and they would get used almost daily.

I have only recently become aware of SMART data from this site, but haven't researched it yet. I just did a quick read and found a link to https://www.smartmontools.org. I'll spend some time tomorrow reading about this. I assume it is software that I install to access the disk's Smart data.

 

[blue1248]

Which SMART system should I use... I am looking for ease of use and intuitive

The Smartmontools by Ozy de Jong
or
S.M.A.R.T. Monitoring Tools from smartmontools.org

 

[Robert Trevellyan]

smartmontools.org is the proper place to start. It's pre-installed in FreeNAS and easily installed in any flavor of *nix. You can also view SMART data by booting a live image of any Linux that includes Disk Utility, e.g. Ubuntu Desktop.

EDIT: see also https://www.smartmontools.org/wiki/LiveCDs