Helium Drives

[TSM]

I could be overlooking it, but I haven't seen very much about helium drives on this forum, other than that they exist.  And no discussion of their value.  

 

Just curious as to everyone's opinion.

 

Are they worth the additional cost?  In the real world actually inside of an unraid server, would there be noticeable performance gains?  Assuming a single Helium drive in the system, and the rest of them traditional, would it make more sense to make the Helium drive a parity drive or a data drive?  I'm thinking that parity calculations would probably speed up only if both parity drives were Helium.  And having a helium drive as a data drive without helium parity, would only give better performance in reads and not writes.  

 

Any reason (aside from cost) to not use a Helium drive with unraid?  

 

Anyone already running them?  Your thoughts?

Edited April 10, 2018 by TSM
clarifying question

[pwm]

Lots of people use helium drives - many without even knowing about it. I have lots of them.

 

The main reason for helium drives is that they have much less power consumption, because there is less drag from the spinning platters.

[c3]

Helium is being used to increase density. It has limit impact on performance, thus parity calculation, etc. https://blog.westerndigital.com/rise-helium-drives/
Any performance gain is related to the density, ie more heads due to more platters from thinner platters.

[pwm]

3 hours ago, c3 said:

Helium is being used to increase density. It has limit impact on performance, thus parity calculation, etc. https://blog.westerndigital.com/rise-helium-drives/
Any performance gain is related to the density, ie more heads due to more platters from thinner platters.

 

It actually have quite  a lot of impact on performance - a helium drive at 7200 rpm can draw less power than a non-helium drive at 5400 rpm because of the lower drag from the spinning platters. And it's an advantage to have a parity drive with faster seek times, giving lower read and write latency.

 

That helium is most common in high-capacity drives is because additional platters gives additional drag and thereby additional power consumption and heat - so the incentive to use helium is larger in high-capacity drives.

[c3]

yes, rpm has an impact on performance. But drives have been running 7200rpm (and much faster) without helium.

[c3]

15 minutes ago, pwm said:

And it's an advantage to have a parity drive with faster seek times, giving lower read and write latency.

Would love to see the data on this as it would end the whole mess about "turbo" writes.

[pwm]

2 hours ago, c3 said:

yes, rpm has an impact on performance. But drives have been running 7200rpm (and much faster) without helium.

 

Yes, I got my first 10k rpm drive (IBM UltraStar 9ZX) about 20 years ago and have also had 15k rpm drives without helium. But with fewer platters. And the 10k and 15k drives are normally quite low-capacity drives - some of them are even 2.5" drives in a 3.5" form factor with much of the case formed as a heat sink because of the additional drag from the higher rpm.

 

Helium is what makes it possible to either get a 7200 rpm drive draw power as a 5400 rpm drive, or allows additional platters while allowing the drive to stay in the same power envelope as a traditional drive.

 

In short - it isn't practical to build a 12 TB drive without using helium because it would run so hot, or have to spin very slowly or have to break the normal form factor limitations. Since customers doesn't accept red-glowing or oversized drives, that means the choice is between helium or a very slow rpm.

[JorgeB]

3 minutes ago, pwm said:

or allows additional platters while allowing the drive to stay in the same power envelope as a traditional drive.

Yep, they can fit 9 platters on a 3.5" Helium drive, AFAIK maximum for non Helium is 6.

[c3]

Helium does reduce the power, (as covered in the WD blog) so much that it is well below traditional drive, even with more platters. It's not an either or.

They do run hot, mostly because the lack of airflow in the traditional drive space. The 8 and 9 platter drives just dont leave any room for air flow.

Edited April 10, 2018 by c3

[pwm]

2 hours ago, c3 said:

Would love to see the data on this as it would end the whole mess about "turbo" writes.

 

No it wouldn't. Without turbo writes, you would still need to perform read/modify/write which means having the drive rotate twice as many revolutions. So you would have to consider 10k or 15k rpm drives - and they have low data densities which means they do not hold much data on each track. A Seagate ST900MP0166 is a 15 krpm drive with 900 GB capacity and it can deliver 200-300 MB/s. It's puny, so to use it for parity with "real" storage disks, many drives needs to be run striped in RAID-0. And 200-300 MB is still not fast enough to do both a read and a write and match the transfer rate of a normal storage disk that may manage 200 MB/s but only needs to do a single read or a single write.

 

And even a 15krpm drive loses lots of bandwidth by performing seeks - 2ms latency is still 2ms when the drive doesn't perform any data transfer to/from any platter.

 

But when you perform writes to multiple data disks, then it's an advantage that the parity disk can do fast seeks because the parity disk will be the weakest link in the chain and control how fast you can manage to write to the data disks. So if a faster rpm and lower latency for the disk can cut away 50 ms seek time every second it can potentially gain you 200 MB/20 = 10 MB/s additional transfer speed.

[pwm]

5 minutes ago, c3 said:

Helium does reduce the power, (as covered in the WD blog) so much that it is well below traditional drive, even with more platters.

 

Yes - and because of this, we will probably see helium introduced in much more drives. Helium isn't expensive, while power consumption matters a lot. And SSD are eating into the HDD market shares so there isn't much need for any low-end, low-capacity HDD.

[c3]

Exactly, there is no performance play in the 8+TB drive business. Same as to where all the 10k and 15k drives are gone.

[HellDiverUK]

I have a few 8TB Helium drives. 

 

The oldest is 2 years old, a white-label WD80EZZX.  No problems with it at all, and I have two other WD80EZZX.  Those were all shucked from MyBooks.

 

I have a 8TB Purple running in a CCTV server, recording 24/7 for about a year now.  It runs quietly and cool, even in the really badly designed Dell it's in (no airflow at all in the drive bay).

 

Finally I'm preclearing a 8TB Gold, and it seems really nice too, it's the first 7200rpm helium drive I've had, and it's as quiet and cool as the other 5900rpm ones.

 

The other 8TB drives I have are traditional air-filled Seagates, and they're loud, hot and use nearly 10W compared to 5-6W for the helium WDs.