18 Tbyte WD : SATA 384 VS SAS 559

[GioMBG]

Hi All,
hoping to find You ALL Well.
While waiting for the new 20 Tbyte WD ultrasatr disks to come out on the market, I saw the price of the 18 Tbyte SATA drop significantly compared to the more modern SAS, in Switzerland the cost difference between these hard disks is marked: the first SATA cost CHF 384 while the SAS other more "modern" cost CHF 559 so for someone like me who wanted to make a RAIDZ3 system with 6 disks the savings using the SATA is considerable : CHF 1050...
The questions therefore are 2, first of all, I can configure a RAIDZ3 system with 6 WD Ultrastar DC HC550 SATA drives ?
And the second, of course, if in your opinion it is really worth it to use SAS when on Tom's Hardware they write that at the end of the count the performance of these is absolutely not significantly faster than SATA.
Thanks in advance !
Gio

 

[ChrisRJ]

To the best of my knowledge, the consensus in this forum seems to be that SATA drives are perfectly fine. Of course you must compare apples with apples, i.e. a data center-grade SAS disk is still better than a desktop-grade SATA disk. But paying a premium for e.g. the SAS version of a Seagate Exos over its SATA cousin, is not worth it.

Speaking of Exos, it may be worth looking at those too. Back in October 2020 these offered the best price per GB here in Germany and were considerably(!) cheaper than the Ironwolf, let alone Ironwolf pro models.

 

[sretalla]

I can configure a RAIDZ3 system with 6 WD Ultrastar DC HC550 SATA drives ?

Yes, that will work. It's enough disks to make Z3 (although you're losing half your disks... maybe reconsider how much risk you're saving by having 3 redundant disks vs the cost of additional storage).

 

[GioMBG]

hi sretalla !
But isn't RAIDZ3 a similar disk configuration to Raid 6 as far as redundancy is concerned ?
Because I thought that with RAIDZ3 on 6 disks only 2 were for the parity and not half as in RAIDZ1 ?
Thank you

 

[sretalla]

I think you're confusing the different traditional RAID types and ZFS types.

Traditional = ZFS
RAID0 = Stripe
RAID1 = Mirror
RAID5 = RAIDZ1 (1 parity* disk)
RAID6 = RAIDZ2 (2 parity* disks)
???? = RAIDZ3 (3 parity* disks)

* just for simplicity, disks aren't actually dedicated to parity, it is written across all member disks in a VDEV.

I'm using the equals sign (=), but these aren't actually "equal", just the closest equivalent.

 

[GioMBG]

T H A N K S !
my case so is RAIDZ2 on 6 disks to support the breakdown of 2 units.

 

[blanchet]

Pick the SATA disks:

• they are cheaper
• you can reuse them later in a desktop computer
• for spinning disks, the performance difference is imperceptible

The SAS disks are useful in the following cases:

• when you have dual-headed solution like TrueNAS X10-HA, and you need to access the hard disks from two different SAS controllers.
• when you have an all-flash-array (SAS SSD have 12Gbps connection instead of a 6 Gbps connection for SATA SSD)

I have a server with 24 x WD DC HC550 WUH721818AL (WD SATA 18TB), they work very well.

 

[GioMBG]

Really Thanks to this forum and his Users,
Understand !
I have to built a RAIDZ2 with 6 SATA drive !
Gio

 

[Chris Moore]

The only additional reason I see to use SAS is if you want to use the new Seagate "Multi Actuator" technology.
You might want to read up on that if you have not heard of it:

Google Search

or

MACH.2 Multi-Actuator Hard Drive | Seagate US

The world’s first multi-actuator hard drive with two independent actuators that transfer data concurrently.

www.seagate.com

It almost doubles the throughput to a drive by making a single drive work as if it is two drives.