What is the best settings for 3 2TB disks

[carlosmdl]

Hello,

I'm new to truenas and NAS in general.
I just build a NAS with this hardware.

Athlon 3000G
16GB RAM DDR4
3 x 2TB WD RED

I want to use this NAS to make backups of my business websites, so its very important data.
Each backup is 20GB size, so the drivers are more than enough to save the last 7 days.

My question is, what setting I use, so I don't lose any data in case a disk dies. Raid 5? 3 way mirror?

Thank you!

 

[danb35]

First, you'll want to make sure those disks aren't SMR--new WD Reds under around 8 TB are, and that just isn't compatible with ZFS. Second, you really have two options, and you've mentioned both of them: RAIDZ1 (there's no "RAID 5" in ZFS, and therefore in TrueNAS) or three-way mirrors. We don't often recommend RAIDZ1 due to the risk of a second drive failure (or read error) on rebuild causing uncorrectable problems, but with disks that small it may work. A three-way mirror will naturally be considerably safer, at the expense of another disk's worth of capacity. If the only data storage need on this system is 7x 20-GB backups (or about 140 GB), I'd go for the three-way mirror, as it's safer and still has plenty of capacity.

 

[carlosmdl]

In 3 way mirror I will have 2TB, right?
I'm building a 2 backup machine with a atom cpu, that will do just that, backup, of the first one.

 

[danb35]

Yes, it'd be 2 TB, less any ZFS overhead.

 

[carlosmdl]

Thank you, I just did that three-way mirror, because the data is very important and this way I have 3 disk with the same data. I also will do a backup to other machine, so I think I'm safe.

 

[sretalla]

I didn't see any response to the point about SMR drives... are those drives old or are they WD RED PLUS? (if no to both, then chances are they are SMR and should not be used with ZFS).

List of known SMR drives

Hard drives that write data in overlapping, "shingled" tracks, have greater areal density than ones that do not. For cost and capacity reasons, manufacturers are increasingly moving to SMR, Shingled Magnetic Recording. SMR is a form of PMR...

www.truenas.com

 

[dspeed]

Do you have a plan to move forward from this point?

How many drives will your case / motherboard / power supply support?

It pays to think well ahead with ZFS.

 

[carlosmdl]

Hi, the drives are SMR, but because I'm using three-way mirrors, thats no problem.
In the future I will add pcie card do have more sata connections and use ZFS with other drives if I need it.
Right now I have 2 free sata connections.

 

[Etorix]

Hi, the drives are SMR, but because I'm using three-way mirrors, thats no problem.

If there's "very important" data involved, I would NOT rely on that…

In the future I will add pcie card do have more sata connections and use ZFS with other drives if I need it.

Fine, as long as you use a proper SAS HBA and not a consumer-grade SATA controller.

Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

With the introduction of SAS 12Gbps, seems like "it's time" to do a braindump on SAS. Work in progress, as usual. History By the late '90's, SCSI and PATA were the dominant technologies to attach disks. Both were parallel bus multiple drop topologies and this kind of sucked. SATA and Serial...

www.truenas.com

Multiply your problems with SATA Port Multipliers and cheap SATA controllers

This resource was originally created by user: jgreco on the TrueNAS Community Forums Archive. Please DM this account or comment in this thread to claim it. In the last year or two, we’ve had a resurgence of users asking about SATA Port Multipliers and cheap SATA controllers. Please, do NOT use...

www.truenas.com

 

[carlosmdl]

If there's "very important" data involved, I would NOT rely on that…


Fine, as long as you use a proper SAS HBA and not a consumer-grade SATA controller.

Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

With the introduction of SAS 12Gbps, seems like "it's time" to do a braindump on SAS. Work in progress, as usual. History By the late '90's, SCSI and PATA were the dominant technologies to attach disks. Both were parallel bus multiple drop topologies and this kind of sucked. SATA and Serial...

www.truenas.com

Multiply your problems with SATA Port Multipliers and cheap SATA controllers

This resource was originally created by user: jgreco on the TrueNAS Community Forums Archive. Please DM this account or comment in this thread to claim it. In the last year or two, we’ve had a resurgence of users asking about SATA Port Multipliers and cheap SATA controllers. Please, do NOT use...

www.truenas.com

If there's "very important" data involved, I would NOT rely on that…


Fine, as long as you use a proper SAS HBA and not a consumer-grade SATA controller.

Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

With the introduction of SAS 12Gbps, seems like "it's time" to do a braindump on SAS. Work in progress, as usual. History By the late '90's, SCSI and PATA were the dominant technologies to attach disks. Both were parallel bus multiple drop topologies and this kind of sucked. SATA and Serial...

www.truenas.com

Multiply your problems with SATA Port Multipliers and cheap SATA controllers

This resource was originally created by user: jgreco on the TrueNAS Community Forums Archive. Please DM this account or comment in this thread to claim it. In the last year or two, we’ve had a resurgence of users asking about SATA Port Multipliers and cheap SATA controllers. Please, do NOT use...

www.truenas.com

Are you telling me that 3 new drives can die at the same time?

 

[danb35]

Are you telling me that 3 new drives can die at the same time?

"Can"? Of course they can. It isn't likely, but it's surely possible. More curious to me is why you think three-way mirrors do anything to mitigate the problems of SMR.

 

[carlosmdl]

"Can"? Of course they can. It isn't likely, but it's surely possible. More curious to me is why you think three-way mirrors do anything to mitigate the problems of SMR.

I read that three-way mirrors copy the same data to 3 drives, so if one of the drives dies I still have that data.
I also have that data in a remote NAS in 1 drive.

 

[Etorix]

More curious to me is why you think three-way mirrors do anything to mitigate the problems of SMR.

I suppose that the thinking is that resilvering a mirror involves a long read operation on the surviving SMR drive(s), which is what they are good at, and a long sustained write operation on the new member—which could be fine if the new drive is not SMR.

Maybe.

For the sake of clarity: If it were my data, I wouldn't count on it.

 

[danb35]

I read that three-way mirrors copy the same data to 3 drives, so if one of the drives dies I still have that data.

That's correct. It does nothing to mitigate the problems with SMR drives.

 

[carlosmdl]

I just want to save the data. I don't read it, or erase it.

 

[spuky]

I just want to save the data. I don't read it, or erase it.

whats the point of saving it then ;-) You don't wan't to read it unless you have to...

 

[carlosmdl]

Its a backup... I maybe need it 1 or 2 times a year, max...

 

[spuky]

Problem with backups is when you need them most often you really do ;-) My take would be If the data is Important enough for a 3 way mirror it should be important enough to choose the right drives for the Job. Most likely it will be not a problem... but nobody will tell you it is the right deccission to go with those drives...

 

[carlosmdl]

I understand.. but I have the same data in 4 drives.

3 drives on my NAS, and another one in my parents house.

I think... but that just me... that I'm ok... 4 drives have to die.. at the same time.