Seagate Exos X18 ST16000NM000J

[elia.cappelli]

Hi all.
I've just recently started using TrueNas and ZFS and I need some advice.
I ordered 2 Seagate exos X18 with 16TB of capacity ( model: ST16000NM000J ) on offer on Amazon for €249 to create a ZFS mirror on TrueNas Core.
Then I read on the internet that discs with protection against power failure are recommended.
I was thinking of using the two Seagates for a "data pool" and two SSD for a "special pool ( with metadata) ".
Can the two Seagates work well with a ZFS mirror and in the event of a power failure I don't lose data, or do I have to send them back to the sender and get two WD Golds ? Unfortunately the price of the WD Golds is almost double that of the Seagates.
Also, for SSDs where I will put the metadata, is it necessary to take disks with protection against power failure?
I was thinking of getting two Kingston DC600M 480GB, or can I get less expensive SSDs like fanxiang S101 512GB?
King regards

 

[Ericloewe]

Then I read on the internet that discs with protection against power failure are recommended.

Eeh, I wouldn't say that in the abstract. ZFS guarantees that data is always correct, transitioning atomically from one state to another.
IF you have sync writes, which would slow things down too much, you can use an SLOG to offload the ZIL to an SSD, which must then support power loss protection, because it's separate from ZFS' full write path.

I was thinking of using the two Seagates for a "data pool" and two SSD for a "special pool ( with metadata) ".

Do you mean a pool with a "normal" vdev with the HDDs, plus a special vdev with the SSDs, for metadata and small blocks? Doable, but you haven't actually told us what you want to do with the server, so it's hard to say if it makes sense.

Can the two Seagates work well with a ZFS mirror and in the event of a power failure I don't lose data, or do I have to send them back to the sender and get two WD Golds ?

There's no such thing as an HDD with power loss protection, so you're not going to end up any better.

Also, for SSDs where I will put the metadata, is it necessary to take disks with protection against power failure?

It depends, not strictly as far as ZFS is concerned, but the SSD itself may end corrupting data if power is lost, which would not be good.

I was thinking of getting two Kingston DC600M 480GB

Those are kinda dodgy...

less expensive SSDs like fanxiang S101 512GB?

but they are better than Super China Happy Sun crap.

 

[elia.cappelli]

Eeh, I wouldn't say that in the abstract. ZFS guarantees that data is always correct, transitioning atomically from one state to another.
IF you have sync writes, which would slow things down too much, you can use an SLOG to offload the ZIL to an SSD, which must then support power loss protection, because it's separate from ZFS' full write path.

Do you mean a pool with a "normal" vdev with the HDDs, plus a special vdev with the SSDs, for metadata and small blocks? Doable, but you haven't actually told us what you want to do with the server, so it's hard to say if it makes sense.

There's no such thing as an HDD with power loss protection, so you're not going to end up any better.

It depends, not strictly as far as ZFS is concerned, but the SSD itself may end corrupting data if power is lost, which would not be good.

Those are kinda dodgy...

but they are better than Super China Happy Sun crap.

Thanks for your reply.
Yes it's correct,
a pool with a "normal" vdev with Seagate HDDs plus a special vdev with SSDs. I was thinking of getting a Fanxiang SSD S101 256GB as an SSD which is at a low price or Crucial MX500 250GB, but I would like to make sure I don't have problems with special vdevs.
Which SSDs would you recommend?
Now I would like to use the trueNas server with Plex, I would like to try creating virtual machines to see how it works and certainly put all the family photos and videos there.
I use an AMD ryzen 5 5600G with asrock B550-itx and 32GB RAM
Best regards,
Elia

 

[Ericloewe]

Which SSDs would you recommend?

SATA SSDs? None, only crap and overpriced enterprise gear remains. NVMe is the way forward and SATA SSDs are quickly becoming a burden more than a transitional tool.

 

[elia.cappelli]

SATA SSDs? None, only crap and overpriced enterprise gear remains. NVMe is the way forward and SATA SSDs are quickly becoming a burden more than a transitional tool.

I was asking you to recommend SSD because to connect nvme disks I would have to add a pcie to nvme adapter, I only have one nvme slot in the b550m-itx and I used it for the operating system.
Adding a four nvme pcie card could be a solution. Which nvme do you recommend for vdev specials?
Regards

 

[Peter Jakab]

Can the two Seagates work well with a ZFS mirror and in the event of a power failure I don't lose data, or do I have to send them back to the sender and get two WD Golds ? Unfortunately the price of the WD Golds is almost double that of the Seagates.
Also, for SSDs where I will put the metadata, is it necessary to take disks with protection against power failure?

About power failure protection the best method if you have UPS (Uninterruptible Power Supply) which is connected to TrueNAS and communicate on low battery condition to perform graceful shutdown (just UPS without communication useless just delay the issue). 10minute battery running time is enough to cover of those problems. Of course those need to be tested (by utility power-off) before you put any risky data on those disks.

If that is not enough/acceptable industry solution bigger UPS + auto-start diesel generator (like keep power-on long term).

 

[elia.cappelli]

About power failure protection the best method if you have UPS (Uninterruptible Power Supply) which is connected to TrueNAS and communicate on low battery condition to perform graceful shutdown (just UPS without communication useless just delay the issue). 10minute battery running time is enough to cover of those problems. Of course those need to be tested (by utility power-off) before you put any risky data on those disks.

If that is not enough/acceptable industry solution bigger UPS + auto-start diesel generator (like keep power-on long term).

Thank you for your answer .

 

[dak180]

There's no such thing as an HDD with power loss protection, so you're not going to end up any better.

This may not be entirely true; I cannot recall where I saw this at the moment (or even if it is in production yet) but I saw something about a drive that a sufficiently large nand cache that it could flush its dram to using the motor as a power inverter during a power loss scenario. This would allow the drive to provide power loss protection with no to little additional hardware needed (and therefore cost).

 

[elia.cappelli]

This may not be entirely true; I cannot recall where I saw this at the moment (or even if it is in production yet) but I saw something about a drive that a sufficiently large nand cache that it could flush its dram to using the motor as a power inverter during a power loss scenario. This would allow the drive to provide power loss protection with no to little additional hardware needed (and therefore cost).

Dak,
I was trying to say exactly this.
Mechanical disks that have protection against power failures I found Western Digital Gold, this is indicated in the WD Gold specifications:
"Help protect your data
Innovative ArmorCache™ (22TB and 24TB only) provides business power
data loss protection in WCE mode (write-cache enabled) during scaling
performance in write cache disabled (WCD) mode."

As regards SSD models, for example, these models guarantee protection in the event of a power failure: Kingston DC600M and Kingston Data Center DC500R:
“DC600M protects data from unexpected power outages to reduce the possibility of data loss and ensure the drive reinitializes correctly the next time the system is turned on”

Thanks

 

[Ericloewe]

This may not be entirely true; I cannot recall where I saw this at the moment (or even if it is in production yet) but I saw something about a drive that a sufficiently large nand cache that it could flush its dram to using the motor as a power inverter during a power loss scenario. This would allow the drive to provide power loss protection with no to little additional hardware needed (and therefore cost).

There was talk of something like that, but I think it is not something that ever made it to market.

Mechanical disks that have protection against power failures I found Western Digital Gold, this is indicated in the WD Gold specifications:
"Help protect your data
Innovative ArmorCache™ (22TB and 24TB only) provides business power
data loss protection in WCE mode (write-cache enabled) during scaling
performance in write cache disabled (WCD) mode."

Not quite the same thing, as I understand it. WD has started using a small NAND volume to hold disk metadata, I expect that means that they also need to hold fewer things in DRAM to maintain performance (because otherwise they'd need to seek to said data on spinning rust). Throw in some optimistic marketing and you get that blurb.

As regards SSD models, for example, these models guarantee protection in the event of a power failure: Kingston DC600M and Kingston Data Center DC500R:
“DC600M protects data from unexpected power outages to reduce the possibility of data loss and ensure the drive reinitializes correctly the next time the system is turned on”

That's pretty universal in enterprise SSDs.

 

[Apollo]

https://blog.westerndigital.com/optinand/

 

[ChrisRJ]

About power failure protection the best method if you have UPS (Uninterruptible Power Supply) which is connected to TrueNAS [..]

This is certainly a good idea, but not the same as an SSD with PLP. The latter will cover additional scenarios like failure of the PSU etc.

 

[ChrisRJ]

All in all there seems to be some level of discussion on edge-cases here. At the end of the day we should go back to requirements.

@elia.cappelli , what are your needs for a NAS? A mirror (built with 2 HDDs of 16 TB each) is a good starting point. Whether or not it is a good idea, let alone necessary, to add a pair of high-quality(!) SSDs for metadata to the pool, depends on a number of things. Also, you will get better advice by letting us now what the rest of your hardware looks like.

 

[elia.cappelli]

All in all there seems to be some level of discussion on edge-cases here. At the end of the day we should go back to requirements.

@elia.cappelli , what are your needs for a NAS? A mirror (built with 2 HDDs of 16 TB each) is a good starting point. Whether or not it is a good idea, let alone necessary, to add a pair of high-quality(!) SSDs for metadata to the pool, depends on a number of things. Also, you will get better advice by letting us now what the rest of your hardware looks like.

Thank you for your answer.
My system consists of two Seagate X18 16TB drives.
asrock b550m-itx motherboard
Ryzen 5 5800G
32GB ddr4 4000
Case CFI A7879 mini-itx case that supports 4 hot swap disks.
1 x 256GB M-2 nvme for the TrueNas Core operating system.

I would like to use the NAS as a Plex server and to put data and videos of my family, of travels, of shots taken that have enormous sentimental value and I would never want to lose.

 

[ChrisRJ]

In that case, interpreting it that data safety is of utmost importance, I would certainly drop the metadata vdev. It adds risk to the equation and your setup is not ideal anyway,

 

[Apollo]

I have retired my old WD RED based pool after I was able to replicate its content to my new ST18000NM000J 6 disk RAIDZ2.
As I bought them at different times and performed a series of evaluation to see if those drives were suitable, I can say I have been very pleased with their performance. It is a bit early to say how good they are on the long run but they have been in service (power on hours equivalent ) between 4 and 6 months.
Even with the most reliable hardware, you will get failure so to be real cautious about it, you need to have proper backup/replication strategy and maybe invest in a good UPS rather than buying more high price HDD.
I think there isn't anything wrong keeping the ST16000NM000J.

 

[elia.cappelli]

In that case, interpreting it that data safety is of utmost importance, I would certainly drop the metadata vdev. It adds risk to the equation and your setup is not ideal anyway,

Hi ChrisRJ,
are you telling me to simply use the two mirrored disks with vdev data without any other vdev?
Did I get it right?
If yes, but in this case without 2 SSD disks for the vdev special I would have lower performance than using 2 disks for vdev data and 2 SSDs for vdev special
It's correct ?

 

[elia.cappelli]

I have retired my old WD RED based pool after I was able to replicate its content to my new ST18000NM000J 6 disk RAIDZ2.
As I bought them at different times and performed a series of evaluation to see if those drives were suitable, I can say I have been very pleased with their performance. It is a bit early to say how good they are on the long run but they have been in service (power on hours equivalent ) between 4 and 6 months.
Even with the most reliable hardware, you will get failure so to be real cautious about it, you need to have proper backup/replication strategy and maybe invest in a good UPS rather than buying more high price HDD.
I think there isn't anything wrong keeping the ST16000NM000J.

Thanks for the suggestion

 

[dak180]

I would like to use the NAS as a Plex server and to put data and videos of my family, of travels, of shots taken that have enormous sentimental value and I would never want to lose.

I would suggest instead of a metadata vdev, a metadata only l2arc using an Intel OPTANE SSD P1600X (maybe with an adaptor).

 

[elia.cappelli]

I would suggest instead of a metadata vdev, a metadata only l2arc using an Intel OPTANE SSD P1600X (maybe with an adaptor).

Very interesting.
Yes correct, my B550M-ITX board only has one M.2 slot which I used for the TrueNas OS.
To be able to use these M.2s I would have to buy a PCIe to M.2, but it could be an excellent solution.
Thank you