Seagate hdd: Doble speed at halv price......

[frodr]

The heading is actually true. I guess "Recertified" is a nicer word for used. I purchased 6 units, set up a ZFS pool (4:2).

 

https://serverpartdeals.com/collections/hard-drives/products/seagate-exos-2x18-st18000nm0092-18tb-7-2k-rpm-sata-6gb-s-512e-dual-actuator-3-5-recertified-hard-drive

 

 

[Lolight]

11 hours ago, frodr said:

The heading is actually true.

I don't think you will see any increased speeds over regular HDDs.

My understanding is that these dual actuator drives require specialized interface componentry and software in order to be able to realize advertised speed increases.

They will present themselves to Unraid as two regular speed, 9TB logical units.

[JorgeB]

The original 2x7TB model was like that, and SAS only, it appeared as two LUNs, the new 16 and 18TB SATA models should appear as a single device.

[Lolight]

27 minutes ago, JorgeB said:

The original 2x7TB model was like that, and SAS only, it appeared as two LUNs, the new 16 and 18TB SATA models should appear as a single device.

Thank you for the correction.

I was looking at the SAS version of the drive.

[frodr]

5 hours ago, Lolight said:

I don't think you will see any increased speeds over regular HDDs.

My understanding is that these dual actuator drives require specialized interface componentry and software in order to be able to realize advertised speed increases.

They will present themselves to Unraid as two regular speed, 9TB logical units.

 

I did a short test copying from a nvme ssd one one server to the other server with 6 x 2x18 sata in raidz2. I say steady 400MB/s. Whether is was the pools performance or the drive I'm not sure. 

[Yivey_unraid]

Bit of a necro dive here, but since these drives are becoming more and more available as refurbed also in Europe I thought I’d chime in here in case anyone else finds this thread.

 

@frodrI believe the performance you saw when copying to your RAIDz2 pool probably was only due to the pool configuration and maybe RAM, not a benefit of the 2X18’s possible speed unless you’ve partitioned the drives.

 

Maybe you’ve already figured this out, if so what’s your speeds now?

 

The SATA interface on the 2X18 aren’t able to show the two separate LUNs so it treats them like one append the other. Meaning the drive will first fill up the first LUN, then the second. The end user will only see regular drive speeds.

 

To benefit in speed from the 2X18 SATA you need to partition the drive according to Seagates own documentation. Then you can access both parts of the drive simultaneously and effectively double your performance. If you then put them in a ZFS pool it’s wise to not add both partitions of one drive to the same VDEV. It gets a bit more tricky and you need to think it through before setting it up, especially in regards to fault tolerance and future expandability.

 

More info here:

https://forum.level1techs.com/t/how-to-zfs-on-dual-actuator-mach2-drives-from-seagate-without-worry/197067/62?page=3

(link to SATA instructions but the thread is a worthy read from the beginning)