NAS drives - my new journey.

[shykitten55]

Hi again folks.

My latest journey is into the world of NAS drives - or storage.

I get there are NAS drives and there are NAS drives.   But to help with what I know here it is:

There are options for the sort of storage offered:  JBOD or RAID.

JBOD is the easiest and the NAS is "Just a Bunch Of Discs".

RAID sort of complicates things as there are many options.
RAID 0, 1, 2, 5, 6, 10 (though I am still not sure if that is TEN or "one plus zero").
And it goes on with hot swappable drives.

Basically I was BACKUP of my data.

I do have a JBOD NAS now, but it is getting on and my computer's drives are also getting on.

But as the options are there, I am wanting to learn about them so I can make a (cough) better choice.

I get that some of the RAID options allow for incitue (?) failure and recovery as a bonus.  Then some "stripe" data over multiple drives.   More for speed than need, I believe.

Of course "Mr Money" comes into the game and shapes what I can buy/afford.   But I don't want to get something which which will "only just" do.  I would prefer a bit of future compatibility with things as time goes on.

That's about it for what I know.

What I want, well...   I'm not sure.
But let's start with a required space of say 5 TB.

I'd like redundancy on the NAS.  I have been "warned" about single disc failure redundancy as being dangerous.
Why?  Because (I was told) that it is a given that a drive will fail/die.
When you rebuild the array, the remaining drives are "stressed" and if a second one dies, it is all over red rover.
So "two drive failure" redundancy is better.

I would like an array which can grow as my budget allows.

Anyone have a good working knowledge of NAS drives and RAID arrays mind sharing their knowledge?

It would be very appreciated by me.

[Andrew Larkin]

RAID 6 is something new to me. Without researching it further it seems like some twist on RAID 10.

 

RAID 1 is mirroring: disks are basically paired and data is written to both.  You get half the space.

RAID 0 isn’t RAID as there is no “R”edundancy.  Same as JBOD. Full drive capacity available.

RAID 10 is a combination of these two. Again, you get half the capacity to play with.

 

RAID5 is where you have data being written across all the disks with parity. The parity data is spread across all drives to share the load. This gives redundancy for single disk failure because the lost data can be reconstructed from the remaining drives and parity. For a 5 drive array, you get 4 drives worth of storage.

 

There are performance hits with all these options.

 

But for backup purposes, I would be inclined towards RAID 5.

 

5x1.5Tb disks will give 4x1.5Tb=6Tb available storage

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[Iain Chalmers]

The Wikipedia article does a reasonable job of outlining what the various RAID levels typically mean.

https://en.wikipedia.org/wiki/Standard_RAID_levels

But these days, the choice is pretty obvious. Just use RAID1 - which is a complete copy of everything you store on two drives.

That means for you 5TB of space, you'll just buy two 5TB (or more likely 6TB due to typically available sizes). This doesn't have your mentioned "one drive fails and then another one fails while rebuilding" problem, since there's not need to rebuild from a parity disk when one fails, since your remaining disk has a complete copy of the entire storage.

RAID 5 (and 6) are not (in my opinion) worth considering for small/home setups - the savings in costs are too insignificant to be worth the hassle or additional risk.

Big

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[shykitten55]

Thanks Andrew and "big".

Ok, RAID 0 and JBOD.  My bad.

So indulge the question (Haven't got to the wiki link yet):
Going with 5, can it "Grow" as I get more discs?

Say I get a 5 bay system but can only afford 2 discs.   Later on, I get more money and can afford more discs.....  Can I make the array grow?
With 5, they all have to the be same size.

It is just I am wanting to get a good backup of my stuff to "keep" and as I get more things - digital pics, movies, etc - keep backup of those too.
So though I stated I want to start with 5TB, it will grow.

Yeah, to what?  I don't know.   But 5 to 6 TB would be a silly thought.  Though 10 TB maybe too much - to say.

I need to have a better idea of the size - given - of what I want to back up.  I just see this as a good time to get some background info on the whole RAID/NAS/BACKUP workings.


Shall look at wiki link now.

[Iain Chalmers]

There's a benefit of "RAID 0" over JBOD, in that it reads/writes half the data to each disk - this can make throughput twice as fast, which is a benefit in some circumstances.

I had one of my MacBook Pro's booting from a RAID0 pair of SSDs for a while, went from powered down to usable in about 6 seconds. Unfortunately one of the recent Mac OSX updates removed the ability to boot from a RAID pair ...

RAID6 is very similar to RAID5, just with a second parity drive so it's resilient to more than one drive failure. This means - like RAID5, you get less total capacity, a 6 drive set gives you a total capacity of 4 drives.

big 

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[Kris]

Slightly off topic, but I recommend open media vault. It's great I've used it for years and I've had a complete system crash and it recovered (the os drive failed and the new os recognised the existing striped array)

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From: Iain Chalmers <big...@mightymedia.com.au>
Sent: 30 June 2017 13:52:57 GMT+10:00
To: "sydney-h...@googlegroups.com" <sydney-h...@googlegroups.com>
Subject: Re: [RnD] NAS drives - my new journey.

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[Iain Chalmers]

RAID 5 (and 6) are complicated to grow. Not impossible, but it required moving a bunch of data around the whole set when you add one additional drive.

RAID1 doesn't "grow" as such, but whats often called RAID 10 or RAID 0+1 is a striped pair of mirrored disks. You can grow that in two drive jumps (depending on your hardware controller or the software raid tool).

But before you choose based on "available storage ratios", go and look at actual drive capacities and prices. Looking on staticice.com.au right now I can buy 6TB drives for ~$290 but 1.5TB drives are $148 (and much less common). So $580 for a pair of RAID1 6TB drives for 6TB of storage, or $740 for 5 1.5TB drives in a 6TB total capacity RAID5 with the risk of total loss if a second drive fails during rebuild.

big

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[Kris]

And you should never buy all raid drives at the same time!
I'm looking at you Seagate!

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From: Iain Chalmers <big...@mightymedia.com.au>

Sent: 30 June 2017 14:03:51 GMT+10:00
To: "sydney-h...@googlegroups.com" <sydney-h...@googlegroups.com>
Subject: Re: [RnD] NAS drives - my new journey.

[shykitten55]

(sorry if this is a double post, machine rebooted while I was typing.)

Yes, well, THAT is the question.

I was with you all the way until the last part:

So $580 for a pair of RAID1 6TB drives for 6TB of storage,
 or $740 for 5 1.5TB drives in a 6TB total capacity RAID5 with the risk of total loss if a second drive fails during rebuild.

But the first option would not work if a crash happened during rebuild too - right?

So putting that aside, the first option is better?

Just now I have a THECUS 2 bay NAS set up as JBOD.   It works.

On top of what was mentioned above is also the cost of the NAS unit itself.
Any preferences?   (Or "Stay away from this brand" warnings?)



Kris,
What is "open media vault" compared to NAS?   A cloud?  Hardware or software?
I'll look into it all the same, but just in case I find an incorrect match.

[Jeremy Nelson]

I run a RAID6 setup at home, and I've run RAID5 or RAID6 setups for... 10 years or more I guess? I moved to RAID6 specifically because I had failures rebuilding a RAID5. I've never grown the arrays, only ever done forklift upgrades after the disk sizes/$ ratios suggested it was time to upgrade.

* For 5T, just mirror the drives. Its easy and reliable.

* Distinguish between "data I really care about" (unbacked up family photos) and "data that is really just a cache" (downloaded content, your CDs/DVDs that you've ripped, etc...). If it is something you really care about, back it up to a separate system. Redundant disks are NOT backups. They won't save you if you've accidentally done a recursive delete.

* A simple rsync copy of all the data you care about to a desktop system with spare capacity is a pretty effective backup- it doesn't have to be complicated.

* If you aren't an experienced Linux Admin and/or you want to do something other than manage your fileserver I think it is a really good idea to use a setup like Openmediavault, or a product that has a built in management interface.

* By all means get a product that does raid or something (a little NAS), but DON'T DO HARDWARE RAID. RAID running off a disk controller is the worst kind of raid in the world- if the card die you have to hope you can get the exact same card or a card that uses the exact same controller. Any of the software solutions- which most little NAS boxes use- can be recovered on different hardware- just plug it in to another linux system, load the right driver modules and off you go. 

* If you want to get fancy, consider ZFS- it has many advantages over linux raid, including easier reconstruction, resizing, partitioning, etc...

* Having returned 5?6? hard drives for warranty replacement I finally worked out what I'd been doing wrong- the idle timeouts on the WD Caviar Greens were quite short and meant the heads parked often. The warranty covered, like 40,000 parks or something in that region. I have drives with several million head parks. Since I turned off Idle Timeout on the drives I haven't had a disk failulre. Doh!

   for D in $(blkid | grep linux_raid_member | perl -ne 'if(m|(/dev/sd\w)|) { print "$1\n"};');do idle3ctl -s255 /dev/sd$D;done

Anyway, my general advice would be: keep it simple. I run a complicated setup because I can, but it buys me very little over a cheap 2 drive NAS. Ten years ago the RAID5 meant I could have a monster 6T of usable raid with 5 disks so it was marginally worth it... now it doesn't really make sense. 5T is an amazing amount of disk space- you can have dozens of TV series, hundreds of movies, thousands of songs all side by side with plenty of space free. At some point you do need to realize that you probably aren't going to watch all those movies and TV series again and start deleting them, but its still thousands of hours of media.

Jeremy.

[Kris]

All things being equal raid 5 will fail more often then raid 1 because the are more posts that can fail.

Hence if you are worried about a fail during rebuild raid 1 is better (statistically)

However, raid is only super useful if you need to recover data from 2 seconds ago.
If you don't mind losing last week's worth of data I would simply go with jbod and plug in an external USB drive once a week (which is what I do) I keep the drive off-site and cold. So I'm immune to burglary house fire and live virus

Though I do have to remember once a week to do the backup.

Two links to follow

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From: shykitten55 <fuzzywuzzy.dog@gmail.com>
Sent: 30 June 2017 14:44:40 GMT+10:00
To: Robots & Dinosaurs <sydney-h...@googlegroups.com>
Subject: Re: [RnD] NAS drives - my new journey.

[Kris]

HDD reliability
https://www.backblaze.com/blog/hard-drive-reliability-stats-q1-2016/

Personally I won't touch Seagate and have found western digital to be great. But that's a sample size of me


Open media vault
https://www.openmediavault.org

---

From: shykitten55 <fuzzywuzzy.dog@gmail.com>
Sent: 30 June 2017 14:44:40 GMT+10:00
To: Robots & Dinosaurs <sydney-h...@googlegroups.com>

Subject: Re: [RnD] NAS drives - my new journey.

[Iain Chalmers]

> But the first option would not work if a crash happened during rebuild too - right?

A "rebuild" of RAID1 is super lightweight and low risk - it's just "read all the data of the non-failed disk and write it to the new disk".

A rebuild of a N disk RAID5 is "Read all the bits of data from the N-1 remaining disks and recalculate the missing data using the parity, then write the recalculated data onto the new disk" - so if any of the N-1 disks fails during the read/calculate/write process (which can take a _long_ time for large disks) you've lost your data. Your 5 disk RAID array has four times as many disks which could fail during rebuild as a RAID1 pair, and the rebuild process is compute intensive as well as io intensive so it also takes longer to run, allowing more time for failure.

I honestly do not believe complex RAID is a win in typical single digit or low double digit TB storage. Just spend the money on enough disks to mirror it all. If you're looking at several tens of TB or if you need the performance benefits of spreading your data across many spindles, your mileage may vary (but you're probably not gonna be asking for advice on random kinda-geeky email lists if you're in either of those positions...)

For the record, my home storage is currently two 3TB disks in a RAID1 mirrored pair, with a 3rd 3TB disk that powers up once a week and takes an rsync update to it's copy. That's my protection agains accidental "sudo rm -rf /" "Oooops, noooooo! I meant sudo rm -rf /tmp  slash TEP, not the entire filesystem!!!" errors (or cryptolocker type malware - remember your permanently mounted 6TB of NAS will get encrypted if you double click that SpecialWinnersOffer.pdf.docx.exe from prizew...@danmurphy.ru ;-)  )

big

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[Paul Hutchison]

I second mirroring if all you are worried about is drives dying. Within the limits of practicality you may wish to consider buying drives separately (different supplier, different brands or, even better, stagger your purchase over a period of time to stagger the wear and hopefully end up with different batches).

WD have been good to me too, their Red drives are a good choice for always-on, moderate use NAS, or Greens if you want lower power.

Another benefit of mirroring is that (assuming *some* data is accessible on each drive), you're much more likely to be able to recreate a full undamaged image using a tool like GNU ddrescue (my favourite data recovery tool, not to be comfused with dd_rescue, sometimes also known as ddrescue...).  You'll have no such guarantee if you stripe anything or use a parity drive.

Paul

[Terry Dawson]

I've had a few generations of Home/SOHO NAS.

In my last upgrade (a couple of years ago), I opted for a QNAP TS-469L, which at the time was at a good price point.

I opted for four 2TB Western Digital "Red" drives and am using then in a Raid-5 configuration which gives me a usable 6TB of usable storage. I opted for Raid-5 because at the time the drives were the most expensive part of the solution and Raid-5 gives you better bang-for-bucks on drive costs.

It really depends on your budget and relative costs of storage devices and your functional and performance requirements. It's a juggle.

regards
Terry

[Cat]

Thanks Terry,

Looking around I can't seem to find any 469L in Oz.   431's on the other hand are "on the list" of shops I have asked.

You are right though:  It is a juggle, though I read it as "Jungle" at first.    Same thing I guess.   ;)

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[JT]

All,
There is a point that I think is being missed:
RAID =/= BACKUP
RAID is a good solution for reliable ONLINE storage, but it is not a
backup strategy.

I learnt this the hard way:
I had a Netgear RAID NAS box - my mistake - never buy Netgear NAS:
I had a power outage that killed the power supply in my NAS; upsetting
as it was only a few years old, but I was working so I could buy the new
model.
Except that the new model used a different INCOMPATIBLE disk format, and
required the disks to be reformatted and the data recovered from backup...

So:
1) NEVER buy Netgear NAS.
2) RAID =/= BACKUP

regards,
- JonT

PS And even if you buy a more sensible brand, offsite backup is
typically faster to recover.
(Don't underestimate the bandwidth of a backpack full of usb hard drives.)

[Jason Ball]

Possibly one of the biggest things I was hoping for from the NBN was the upstream bandwidth, to facilitate useable offsite backups.

In my case I was planning to install a NAS at the in-laws and backup to there.  Failing that, crashplan or similar.

But alas, NBN isn't looking all that promising.

J.

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[tALSit de CoD]

Here's my comments. I've been running a home NAS system for about, well... about 10 years now. At first It was just a custom built Linux box with RAID5. The newer Linux boxes, just migrating disks over, or growing the disks, etc. I then went to Synology, keeping the RAID5. About 2 years ago, I went to burn a copy of my Win7 ISO to install a new computer, but it failed CRC (or MD5, I forget). I had lost data due to bitrot on a RAID5 system. That's just the data I know I've lost, there's no easy way to verify everything.

This year I built myself a new system using FreeNAS & ZFS. I make sure to use only ECC memory, and I do periodic checks on the data. Yes, ECC, ZFS (In raidZ2 config) is more expensive than not, but it's my life's data. ZFS has mechanism to do data integrity verification.

The awesome thing about ZFS (especially with FreeNAS) is the periodic snapshots - I have it set up to do daily/weekly snaps, depending on the data. If I accidentally "rm -rf /" (which you can't) (or if I get attacked by ransomware), it'll just be reflected as the delta from the previous snapshot and I can easily recover. THIS IS NOT THE SAME AS BACKUPS!

The biggest downside to ZFS (and the reason why I almost didn't do ZFS) is that you cannot grow "volumes". It gets a bit complicated with nomenclature, but you cannot do the same thing as with RAID5.

My recommendation: look at ZFS.

// talsit.org

[Kris]

I've moved to Optus HFC and it's great.
I was with internode whose service is excellent but I was limited to ADSL annex m which got me maybe 1.2mb up.

The Optus still doesn't have very good upload (3mps) but it's solid and in testing is about 4.


I recommend you call Optus and haggle.

I've also heard bad things about NBN which is a real shame.

Telstra 4gx night hawk is an interesting product, real world testing shows 123 down and 40mb up. Though not in Sydney yet.

---

From: Jason Ball <ja...@ball.net>
Sent: 4 July 2017 10:19:53 GMT+10:00
To: "sydney-h...@googlegroups.com" <sydney-h...@googlegroups.com>
Subject: Re: [RnD] Re: NAS drives - my new journey.

[hack...@raf.org]

tALSit de CoD wrote:

> The biggest downside to ZFS (and the reason why I almost didn't do ZFS) is
> that you cannot grow "volumes". It gets a bit complicated with
> nomenclature, but you cannot do the same thing as with RAID5.
>
> My recommendation: look at ZFS.
>
> // talsit.org

btrfs might also be worth considering.
it can do most of the great things zsh does
and more (including resizing volumes).

cheers,
raf

[Terry Dawson]

This is an old message I'm responding to, but for what it is worth, most commercial NAS are Linux-based.

I know for a fact (I have two of them) that the various generations of Netgear NAS RAID is relatively easily mountable and readable on any Linux machine. Your data was relatively easily recoverable.

Your point about Raid != Backup is valid though.

regards

Terry

[Cat]

Hi.   Thanks for the input.

Granted RAID =/= BACKUP, but I think there are crossed purposes here.

I have a machine - what ever O/S, etc.

As is:  If its hard disk goes belly up:  I've lost EVERYTHING.

If I have a copy of the HD on a NAS and the drive goes belly up, I'm ok.  I have a copy to go back to.

Because I don't have the NAS on 24/7 - even more now with what electricity costs - It is an "off line" copy, as I see it.

I am not going to back up 5 TB of data to the net.   It would kill my ADSL account.

I just want a known good back up of the data.

That is silly though if said back up is "prone" to failure too.   (I am not sure what that means exactly, but please indulge my paranoia)

Then I am just going to get mad.  So I thought of a RAID NAS.

Alas that opened up a whole can of worms to what kind and all the associated questions.

So I am still stuck with what to do.   Oh the fun of learning.

Going now.  Too cold to type without making mistakes and having to go back and correct them.

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[Terry Dawson]

In all seriousness, if all you want is backup for your desktop machine, get a couple of external USB hard drives, backup to them and rotate them.

Terry