Bad JBOD Controller Experience

[Adam Tyler]

I will share what I have done, but it will still cost some money. If you enjoy tinkering it is a fun thing to work on.
Watch these videos on the YouTube:

https://www.youtube.com/watch?v=MgNpI6VAAhI&t

https://www.youtube.com/watch?v=KHiucyRYX_w&t

https://www.youtube.com/watch?v=p39mFz7ORco&t


If you want, you can do what I did and use a pair of laptop drives in a mirror to install FreeNAS on. The FreeNAS installer handles setting up the mirror and I picked up a pair of "New, old stock" 40GB laptop drives for about $8 each on eBay.
The SSD you have may not be ideal, but you can use it. I would suggest getting better hardware as quickly as you can afford it.

Any time you have a question, just ask and someone here will try to help.

Interesting... So these are older HDD drives you got or SSDs? FreeNAS "Handles" the mirror? With my setup I would just connect them both to the SATA ports on the Mobo. How difficult is the FreeNAS OS mirror to setup?

 

[Adam Tyler]

PS. No, the amount of space that will actually be used for SLOG is limited by the network speed and even with 10GB, you will probably never use more than about 32GB and that is an extreme outside maximum. The point of SLOG is to mask latency by making the initial write to fast SSD instead of slow HDD and then the system can move the data over to the HDD in a normal transaction group, 'behind the scenes' instead of making the VM wait.

Seems a little silly to dedicate a 128 Gb SSD to the SLOG then.. What happens if your SLOG disk fails?

 

[danb35]

FreeNAS "Handles" the mirror?

Correct.

With my setup I would just connect them both to the SATA ports on the Mobo.

Also correct.

How difficult is the FreeNAS OS mirror to setup?

Not in the least. When you run the installation, select both disks; it will create the mirror automatically.

 

[Adam Tyler]

This is the best photo I could find quickly.

So couple of questions regarding this photo after I took a minute and looked at it. See my attached photo with comments.

 

[Adam Tyler]

Correct.

Also correct.

Not in the least. When you run the installation, select both disks; it will create the mirror automatically.

The install handling the mirror at install is kick a$$. Thanks.

 

[Chris Moore]

So couple of questions regarding this photo after I took a minute and looked at it. See my attached photo with comments.

They only needed that ribbon cable to connect the card to the system board because they used that stupidly small system board and it didn't have room for the full x8 connector of the SAS controller to fit. You don't have that problem with your board.

Seems a little silly to dedicate a 128 Gb SSD to the SLOG then.. What happens if your SLOG disk fails?

A drive failure in the SLOG would be bad. It is best to have a mirror or a very, VERY high endurance drive. This is the reason I pointed you at those discussions of SLOG drives. The larger drive does allow more spare memory cells to give the drive more endurance.

So these are older HDD drives you got or SSDs?

In my NAS, I use 2.5" laptop style drives for the boot drives. I have been running that way for about three years now with no trouble from the drives at all. The drives I got had zero power on hours when I got them. Still factory sealed.

 

[danb35]

A drive failure in the SLOG would be bad.

Only if it happens at exactly the time that, say, power is pulled on the system after a transaction was written to the SLOG, but before it's written to the spinners. Otherwise, a SLOG is pretty much write-only.

 

[Adam Tyler]

No, the SLOG needs to be its own device.

Okay, so been doing some research on ZFS and SLOG. It seems that each drive in a ZFS array has a ZIL and for optimum performance it is best to dedicate an SSD for all disks to use. This is known as "Separate ZFS Intent Log" or SLOG. Is that understanding about right?

How awful is a Samsung 128 Gb EVO SSD drive to use for something like this? Bad idea?

 

[Chris Moore]

It seems that each drive in a ZFS array has a ZIL and for optimum performance it is best to dedicate an SSD for all disks to use. This is known as "Separate ZFS Intent Log" or SLOG. Is that understanding about right?

Sounds about how I remember it, which is why I was saying a SLOG device would help your pool (for ESXi via iSCSI) perform better.

How awful is a Samsung 128 Gb EVO SSD drive to use for something like this? Bad idea?

If your budget is strapped, it would be better than not having anything, but it is less than ideal.

You might want to take a look at these threads where the user is doing some testing with several options to see what would work best:

Initial Setup/Design:
https://forums.freenas.org/index.php?threads/multiple-volumes-or-not.45545/#post-308867

A bunch of test results for reference:
https://forums.freenas.org/index.php?threads/slow-writes-on-ixsystems-hardware.46032/page-3

 

[Adam Tyler]

These videos are good. Thanks for sharing. How much space do you need for the FreeNAS OS itself? Could I get away with a couple of 16 or 32 Gb SDcards mirrored? They have some now that will go up to 70 MB/s.. Seems acceptable for a boot/config device....?

I could use a couple of the available internal USB 2, 9 pin connectors on the board I own. Do something like this:
https://uedata.amazon.com/Bplus-U0909A-USB2-0-Header-Reader/dp/B00TESOQCW?ie=UTF8&dpID=41vOte1AuUL&dpSrc=sims&preST=_AC_UL160_SR160,160_

Terrible idea?

 

[danb35]

Could I get away with a couple of 16 or 32 Gb SDcards mirrored?

SD cards are an even worse choice than USB sticks. As far as capacity, I'd go for at least 30 GB.

 

[Chris Moore]

How much space do you need for the FreeNAS OS itself? Could I get away with a couple of 16 or 32 Gb SDcards mirrored? They have some now that will go up to 70 MB/s.. Seems acceptable for a boot/config device....?

If you want something that will connect by USB and be more reliable than a USB Stick, you could look at something like this:
https://www.ebay.com/itm/New-Kingsp...odule-64GB-9-Pins-EUSB-DOM-Flash/182631921582
They have other sizes. This one is 32GB, which is plenty:
https://www.ebay.com/itm/New-Kingsp...rial-Embedded-USB-Disk-on-Module/262850750696

 

[Adam Tyler]

Okay, I "bit the bullet" and put a little more $$ toward this. Because I simply don't want to wait any longer for parts. New FreeBSD compatible controller should be here tomorrow. I have two 128 Gb Samsung SSDs I plan to use for the SLOG. I purchased two more Patriot "60" Gb SSDs for the "OS" mirror today. Will probably install the OS tonight and get everything mounted up.. Now just figuring out how to configure FreeNAS after all this TALK! :)

Is there an easy to follow guide for creating the vdev/zpool and adding a mirrored SLOG? Because I have 8 WD red drives, I had planned to copy my previous config and create "4" mirror vdevs allowing the zpool to "stripe" read/write across the "4" mirrors. Not sure how to add a mirrored SLOG.

Is this the best way to build the zpool for performance? I am willing to sacrifice half the capacity for RAID 10 like performance. I know ZFS is a little different, but it seemed that mirroring drives into their own vdev was a way to sort of get that type of speed/failover. I realize that you only get one drive per vdev resilience.

 

[Chris Moore]

Here is a video. Ignore the part where they recommend using a USB drive to install the OS on and say that a SSD is not recommended. They got that backward. There are also directions on installation in the User Guide:

Edit, link corrected: https://www.youtube.com/watch?v=R3f-Sr6y-c4

I had planned to copy my previous config and create "4" mirror vdevs allowing the zpool to "stripe" read/write across the "4" mirrors.

This is a fine way to create a pool for use with iSCSI

Install the pool first. Then the SLOG can be added later.

 

[Chris Moore]

This is an interesting video about L2ARC that will help you understand the capability to accelerate system performance.
https://youtu.be/oDbGj4YJXDw

 

[Adam Tyler]

This is an interesting video about L2ARC that will help you understand the capability to accelerate system performance.
https://youtu.be/oDbGj4YJXDw

Thanks, took me a while to wrap my brain around SLOG.. I really haven't started looking at L2ARC. Will be interesting to see how this array performance with the pieces I have collected thus far. I am hoping it blows the doors off my co-workers 6 drive i5 based Qnap. ;)

 

[Chris Moore]

Thanks, took me a while to wrap my brain around SLOG..

Here is a post with a nice 'step by step' of the process of adding a SLOG to an existing pool:

https://forums.freenas.org/index.ph...n-ixsystems-hardware.46032/page-3#post-313538

 

[Adam Tyler]

Here is a video. Ignore the part where they recommend using a USB drive to install the OS on and say that a SSD is not recommended. They got that backward. There are also directions on installation in the User Guide:
http://doc.freenas.org/11/freenas.html

This is a fine way to create a pool for use with iSCSI

Install the pool first. Then the SLOG can be added later.

Video, that link looks like a FreeNAS user guide?

 

[Adam Tyler]

Here is a post with a nice 'step by step' of the process of adding a SLOG to an existing pool:

https://forums.freenas.org/index.ph...n-ixsystems-hardware.46032/page-3#post-313538

Not sure I really follow this one. Maybe it will be more clear when I am actually in the interface following along. Does the process change at all if you are trying to add a "mirrored" SLOG device?

 

[Adam Tyler]

This is an interesting video about L2ARC that will help you understand the capability to accelerate system performance.
https://youtu.be/oDbGj4YJXDw

So this blew my mind. I will definitely be adding an L2ARC drive as soon as I have the $$ to drop on a 1 Tb SSD. Good stuff.