2 SSD HD in software RAID

[BlazeStar]

Hi,

I'm making a new installation of FreeNAS-9.2.1.3-RELEASE-x64.

I have

2 X 80 GB SSD

and

4 X 4 TB HDD

The 4 X TB HDD are controlled by a RAID card and are in RAID 10.

I would like the 2 X 80 GB SSD to be in software RAID, and install FreeNAS on them.

I was expecting to get this kind of option when installing FreeNAS, but it turns out there is no such option in the installer.

What would be the best practice to achieve that please?


Thanks !

 

[cyberjock]

Did you read the manual? you have no option because you are supposed to install to a USB stick.... /facepalm.

 

[aufalien]

I'd first suggest reading 2 articles;

1) CyberJocks FreeNAS intro.

Then

2) FreeNAS manual which is beautifully written.

You will be empowered. The saying "teach a man to fish..." is very true.

I also personally think that when ppl don't take the time to read what some one has spent a long time in writing, its like you disregard them, a sort of pffffttttt.... I've written manuals and its very tedious and not all that fun.

By no means am I sticking up for any one on this forum as I've had issues. But lets call a spade a spade here.

 

[BlazeStar]

Thanks I was reading the FreeNAS manual while waiting.

Another question I have... I don't see anywhere how you can set a system-wide proxy in the manual... where can I find such info?

 

[aufalien]

I don't know what that is but I'd like to emphasize why FreeNAS is run off USB. Its an appliance approach and very cleaver. It also frees up valuable storage for data use. One also has simple DR if a config backup is made. There is no need to mirror the OS here, thats a very old way of doing things which ppl follow simply because thats how it was done.

As an example, if ppl always did what others of the past have done, then the Wright Brothers would have stuck with riding horses.

 

[BlazeStar]

So you mean I shouldn't even install it on a SSD drive, I should simply always boot from a USB key?

 

[gpsguy]

Yes that is correct.

While your at it - ditch the hardware RAID card. ZFS needs direct access to the hard disks.


Sent from my phone

 

[BlazeStar]

But a SSD drive is pretty much like a USB stick, except it's larger in size... so except the waste of space, what's the problem with installing on a SSD drive, with software RAID 1 so you get a mirror of the OS and it's config??

BTW, CyberJock PowerPoint is awesome... thanks!!!

 

[aufalien]

You can use those SSDs as a ZIL/L2Arc if needed. Configs are best backed up off the appliance.

 

[BlazeStar]

So I read more about ZIL / L2ARC

I think I will change my whole setup and run FreeNAS on a USB stick

Then use the 1 SSD for ZIL, the other one as a mirror (as suggested in the PowerPoint presentation)

However, two questions remain, and I haven't found my answers in the manual or the PowerPoint (yet)

1) How and where to store the FreeNAS configuration ?

2) Why isn't it a good idea to use hardware Raid 10 ?


Thank you

 

[gpsguy]

You don't have a choice as to where to store the FreeNAS configuration. It's on the 4th partition of the boot device (/data/freenas-v1.db). That being said, consider creating a cron job to back it up. There are sample scripts on the forum that you could use.

Please see the manual or do a forum search for the for answers as to why ZFS and hardware RAID don't play well. Just search for "hardware RAID" in the .PDF file.

 

[cyberjock]

While you are at it, read what I say about the ZIL. Then realize you won't benefit from it and don't use it.

Then, because you'll probably think you want an L2ARC instead. So read what I wrote about the L2ARC and then realize you won't benefit from that either.

Then, take those SSDs and use them in your desktop or something.

 

[BlazeStar]

Hi Cyberjock,

Thanks for your valuable feedback.

So up to now I've decided to drop the "RAIDing" but I still need the RAID card for additional slots for all my hard drives... i'll just set them to JBOD mode.

I'll just use "Striped Mirrored" Vdevs, unless you'd have a better suggestion.

Also, from the PPT:

I did understand why I should NOT use L2ARC.

What I still don't understand is why I shouldn't use ZIL with my two SSD drives.

Enterprise class SSD or SSD based on SLC memory is recommended = YES
Having an UPS on a server with a ZIL is a big plus! = YES
It is highly recommended that ZIL drives be operated in a mirrored mode to prevent data loss for this reason. = YES

So why shouldn't I use ZIL ?

 

[joeschmuck]

You shouldn't use the ZIL because you will never benefit from it. You have just added something else to possibly fail and it's not needed. You could use it but again, you will not benefit from it.

As for placing FreeNAS on a SSD, you certainly could do that, place it on one of the SSD's but again it's a waste of a SSD. And as for your configuration files, you have the GUI option to create a backup of your configuration file and save it off your FreeNAS machine in case you ever need to restore it. Everyone should do this operation once they have the system configured.

And I'm not sure about the JBOD mode, but someone will chime in if it's good or bad. So are you saying that your motherboard doesn't have four SATA ports? If the answer is no, what is your MB?

 

[cyberjock]

Anytime you are making a decision(ANY decision in life) the question to always ask yourself is:

[PANEL]Will doing this provide a benefit that outweighs the risk?[/PANEL]

For example:

Do I pay my electric bill? Well, if you don't pay it you get your electricity turned off and that's really bad. But there's a risk if you mail them a check or pay online you might be a victim of fraud. So will the benefit(aka my electricity stays on) outweight the potential risks of becoming a victim? Most people will mail that check.

But... if there is no benefit, but a non-zero risk, then what you are doing is obviously stupid. You're incurring additional risk for zero benefit. Guess what.. that's *exactly* what you are doing by adding stuff that you can't use. So when I say stuff like "don't add an L2ARC or ZIL until you know you need one" I've already leaned you towards that question you should already be asking yourself every single day. I wrote my guide in a very specific way with very specific wording because I want it to be abundantly clear what you should and shouldn't be doing.

The solution is not to throw more hardware at it "because". You engineer and manage the box like a professional or you be an amateur and do stuff "because" and for the "e-penis" and then you show me your "oh shit" face when you lose your data. Which one you want to do is totally up to you. I know I make good money recovering data from amateurs. :)

 

[aufalien]

While both CJ and JS have much more experience than most on this forum including myself, I offer this advice;

Find out for yourself. A sort of trust but verify.

Those guys know what they know through trial and error, R&D etc... No reason you can't do the same.

So do a before and after with whatever config you have. Do all the configs and run as many monitoring tools as you can, like;

gstat
zilstat
arctstat.py using various aruments
zfs-mon (from a jail)

Rather then run benchmarks and potentially suffering from analysis paralysis, run the tools during production.

You can remove zil/l2arc etc live so no biggy. I'd logically remove em, meaning not pulling em out but going through the GUI or CLI after using your filesystem and not during its usage.

As far as apps that write sync vs async, local apps do as well. In other words, NFS and hypervisors aren't the only kids on the block to do sync call backs. It all depends on how the app was written.

A quick an easy way is to monitor zilstat as it only gets tickled during a sync.

 

[BlazeStar]

Why does everyone say ZIL is useless?

Why does it even exist then?

I have a three nodes high availability virtualization envrionnement that will access the files on the FreeNAS via NFS.
I thought this was a good use of ZIL!

I really, REALLY appreciate all of your comments, I would just like to understand WHY?

I did read the Power Point and the manual over and over, and I can't find my answer.

 

[aufalien]

I built a few log servers, no ZIL or L2ARC, no need. Stats showed that there was no benefit so why add the extra parts?

It depends on use case, you really should find out for your self if ZIL would benefit your particular setup/usage instead of asking why all the time.

 

[BlazeStar]

I would just like to get back to my RAID card thing.

I need to have at the very least 6 SATA slots.

I have 4 X 4TB drives and I intend to do stripped mirror vDevs... any comment on that? I think it's the equivalent of RAID 10 if I'm not mistaken

Then I have 2 X 4TB drivers that I intend to use strictly to make ZFS snapshots... is that a good idea ?

Then I also have my 2 X SSD drives that I might take out, but if I don't I need a total of 8 slots.

Whitout a RAID card I don't have enough slots.

So if I put it in JBOD mode, will that work or not (allow ZFS to have access to the drive) because I was sure it would but joeschmuck said it might now work



ALSO, I'm trying to go with that FreeNAS running on USB key but I'm having problems on the part on HOW to make it so the key is read-only and the config and plugins are stored in jails...

From the PowerPoint it says
"Programs and files should not be installed to the FreeNAS USB stick.The USB stick is kept in a read-only mode to maximize the USB stick lifespan.The available space on the USB stick is also very small(just a few MB). FreeNAS needs this space, so don’t assume you can use it.If you do want to install programs in FreeNAS/FreeBSD the jail is designed to provide this function. It is a minimal installation of FreeBSD and should allow you to install anything you like. Using the jail will require you be familiar with the FreeBSD command line. Consult the manual for instructions on installing and using the jail."

Then I go to this place:
http://doc.freenas.org/index.php/Jails

Which is a fair description of the Jails, but I'm still puzzled on how to do it...

Let's say I begin by creating a USB stick and make it read-only, then run FreeNAS from it, then do my stuff (create volumes, etc.), then create a Jail (which type?)...
But then, how do I make it so the FreeNAS config is store on that Jail?


Also saw this :
http://doc.freenas.org/index.php/FA...ey_keep_disappearing_after_a_reboot.2C_why.3F

I'm even more confused... this basically says : configure your system on the USB stick, then make it read-only.
Also save a config on your desktop so if the USB stick fails you just burn another one, and import config...

Sorry for being a total n00b but is there, somewhere, a step by step way to do it for retarded people like me?

I know you guys are all about "Read The Freakin Manual and PowerPoint" but God help me I DID! And it was beautiful! And I feel born again!

...but I still have questions

 

[cyberjock]

A ZIL(and an L2ARC) is only useful for very specific scenarios. Then, for those very specific scenarios they will only provide a benefit for certain hardware configurations. So unless you meet the scenario requirement and the hardware configuration you will not see a benefit. 99% of home users are not going to drop enough money on their server to meet the hardware configuration. But *every noob* is convinced they need "moar speeeeeeed" and think that adding stuff is a great idea. This isn't windows. Adding stuff for e-penis is stupid and will get your data killed off.

ALSO, I'm trying to go with that FreeNAS running on USB key but I'm having problems on the part on HOW to make it so the key is read-only and the config and plugins are stored in jails...

As for how to make your USB stick read-only.. it is read only by default. You don't have to do anything. Your config file goes on the USB stick, where it's supposed to go, and writes only happen when the config changes(so not that often after initial setup). Your jails have never gone on the USB stick so you don't have to worry about the jails. Look at the jails -> configuration screen and see "Jail Root"... that's where your jails go. Hint: You can't even choose the USB stick even if you *wanted* to!

Let's say I begin by creating a USB stick and make it read-only, then run FreeNAS from it, then do my stuff (create volumes, etc.), then create a Jail (which type?)...
But then, how do I make it so the FreeNAS config is store on that Jail?

First, you don't "make" the USB stick read only.. FreeNAS does that during bootup.

Your FreeNAS config is stored on the boot media. It *has* to be on the boot media because of how FreeNAS is configured.

You're sweating over minutia. Just use FreeNAS from the WebGUI as the manual calls out and you won't have any problems.