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15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

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Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#81

Post by kdkeyser »

chrisper wrote: post #2

It's an SMR drive. So better for archiving than regular IO

If you are the target audience for these drives, you likely don't even consider regular (i.e. including random) IO as a use-case for modern HDD's . 10+ TB HDD's really only make sense for sequential IO, even if they technically still support random writes (e.g. the 10 & 12 TB PMR drives): the order of magnitudes of difference in random vs sequential IO performance make this a no-brainer.

If you look at the design of, for example, DropBox Magic Pocket, or Infinidat & Qumulo, you'll notice that their HDD access is really as sequential as possible. And if your storage layer is thus already optimized towards sequential writes, why not take the opportunity and get some capacity "for free" by adopting SMR drives?

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#82

Post by wtallis »

StillBored wrote: post #58
johngalt wrote: post #53

Earlier quoted context omitted.

Tapes have a use case that hard drives do not. Tapes are the lowest cost/GB stored and are more shelf stable than hard drives. SSDs are higher performance than HDDs and have none of the packaging constraints. Flash storage is going to be put into everything and the economies of scale look quite good. Storage is scaling but the r/w speeds of hdds aren't keeping up. Following the trend line and we see huge hdds that ar…

You might be right, but keep in mind that flash has been scaling due to the shrinking semiconductor feature sizes (and additional layers/etc). So a large part of flash's core R&D & production costs are being spread over all the logic being produced. That has been hitting a wall, so while the capacity/price curves for flash look nice, they likely won't continue, which leaves open the possibility that if rust actually…

Horizontal feature sizes for flash memory stopped shrinking years ago. The continued improvements in density and production cost have been the result of R&D that is very specifically focused on 3D NAND flash memory and has little in common with R&D for logic circuit fabrication.

That said, on the horizon of multiple years, I agree that the future scalability of NAND flash doesn't look quite as promising as HAMR/MAMR for hard drives. How that translates into actual product demand and adoption will probably depend on the relatively unexplored question of how much performance per TB our applications actually need. 40+ TB hard drives might not be fast enough to actually serve as nearline storage for that volume of data without eg. multi-actuator technology that essentially gives you more than one hard drive sharing a common spindle motor. Meanwhile, there's no question that QLC NAND flash definitely has adequate read latency and throughput.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#83

Post by kdkeyser »

mjevans wrote: post #60
Hei1Fuya wrote: post #13

Earlier quoted context omitted.

Copy on write filesystems can probably be optimized for SMR by using TRIM commands to punch holes and rewrite the content sequentially in a new zone. Afaik both zfs and btrfs have plans to do this. That way they can be useful for more than archival.

I was thinking that F2FS might be a good filesystem as a base on which you'd use an object storage abstraction layer (like ceph)... However since I initially saw the news of these drives a few days ago Samsung also axed some Linux devs, which gives me pause and makes me reconsider the long term viability of this filesystem... https://en.wikipedia.org/wiki/F2FS

A full blown filesystem is overkill for an object store. You could use something like libzbc ( https://github.com/hgst/libzbc ) to write directly to the SMR drives on the block level.

I believe Ceph now has abstracted the drives away through BlueStore, which simply puts a large RocksDB database on the drive, bypassing most of the functionality a filesystem offers. It should be much easier to make an SMR compatible version of the LSM-tree backend of RocksDB, than writing a full-blown file system.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#84

Post by gamegoblin »

teraflop wrote: post #79
gamegoblin wrote: post #77

Earlier quoted context omitted.

I know Amazon prices aren't exactly perfect for enterprise storage costs, but they imply tape is at least 4x cheaper (assuming you are using enough to amortize the cost of the tape drive): 6.25TB tape is $28 : https://www.amazon.com/HP-HEWC7976A-Ultrium-6-25TB-Cartridge... 6TB HDD is $120 : https://www.amazon.com/Seagate-Expansion-Desktop-External-ST... EDIT: Commenter below points out this 6.25TB tape is actualy 2.5…

That's an apples-to-oranges comparison. The "6.25TB" number for LTO tapes is assuming a fairly arbitrary 2.5:1 lossless compression ratio. The actual data capacity of the tape is only 2.5TB.

You're right. Though, that's still 2x cheaper in terms of $/GB.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#85

Post by paavoova »

simias wrote: post #31
Latteland wrote: post #3

I am going for the 15tb instead of that 14 so I have extra space for backups. Says no body. We are clearly close to the end of spinning rust, absent some new breakthrough.

For archival spinning rust is still massively more cost effective than SSDs while offering better performance than tape, especially for random access. I'm sure eventually SSDs will be cheap enough that HDD will go the way of the floppy but we're not there yet.

You can't use flash storage for reliable unpowered archival. It degrades (gates leak electrons) over time, unlike magnetic storage. This is also unpredictable, as reliability depends on both operating and power-off temperatures, as well as existing wear. See: https://www.anandtech.com/show/9248/the-truth-about-ssd-data...

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#86

Post by klodolph »

gamegoblin wrote: post #77
aidenn0 wrote: post #45

Earlier quoted context omitted.

Is tape even cheaper than spinning rust? Last time I priced it, the per-GB costs were similar and the tape drives themselves are quite expensive. Tape is a more reliable backup, since the moving parts are not part of the storage, but it's not a cheaper backup.

I know Amazon prices aren't exactly perfect for enterprise storage costs, but they imply tape is at least 4x cheaper (assuming you are using enough to amortize the cost of the tape drive): 6.25TB tape is $28 : https://www.amazon.com/HP-HEWC7976A-Ultrium-6-25TB-Cartridge... 6TB HDD is $120 : https://www.amazon.com/Seagate-Expansion-Desktop-External-ST... EDIT: Commenter below points out this 6.25TB tape is actualy 2.5…

You've got the wrong info, LTO-7 is 6TB and $67: https://www.amazon.com/Fuji-Ultrium-7-Data-Cartridge-1645657...

LTO-6 (what you linked) is not 6.25TB, it’s 2.5TB, despite what Amazon says.

Then add the operational costs, which is the hard part, because the operational costs for a tape are very different from the operational costs for a hard disk.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#87

Post by kdkeyser »

jmpman wrote: post #47
stephengillie wrote: post #21

Earlier quoted context omitted.

This is one reason why RAID 0+1 is a best practice, and RAID 5 & 6 are no longer recommended. It takes too long to rebuild the array, leading to a multi-failed disk situation.

CRUSH algorithms are used to overcome rebuild limits in modern arrays. https://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf

CRUSH is an example (and not the first) of a "distributed rebuild" approach: you have an array of N drives (with N large, e.g. 100), and if 1 drive fails, you read in parallel from all (N-1) remaining drives, while distributing the reconstructed data across the remaining available capacity of all (N-1) remaining drives.

In effect, you get the total bandwidth of (N-1) HDD's working in parallel. And the bandwidth of 100 HDD's doing sequential IO in parallel is really massive ( ~ 10 GB/s).

Examples of companies claiming to use this approach are Qumulo (rebuild in couple of hours), Infinidat (couple of 10's of minutes), ClusterStor GridRAID (now part of Seagate I think), or "Declustered RAID" in GPFS (IBM)

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#88

Post by dktoao »

tallanvor wrote: post #26
Latteland wrote: post #3

I am going for the 15tb instead of that 14 so I have extra space for backups. Says no body. We are clearly close to the end of spinning rust, absent some new breakthrough.

HAMR and then HDMR are expected to allow data densities to increase by 5 to 10 times what is currently achievable. HAMR will probably start showing up in a year or two. Spinning drives are definitely not going away anytime soon unless there is a much more significant drop in the cost of SSDs.

Multi-actuator drives are also coming in the next few years:

https://blog.seagate.com/craftsman-ship/multi-actuator-techn...

That will close the performance gap a bit too I suspect. I have to wonder about power consumption though.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#89

Post by wtallis »

dktoao wrote: post #88
tallanvor wrote: post #26

Earlier quoted context omitted.

HAMR and then HDMR are expected to allow data densities to increase by 5 to 10 times what is currently achievable. HAMR will probably start showing up in a year or two. Spinning drives are definitely not going away anytime soon unless there is a much more significant drop in the cost of SSDs.

Multi-actuator drives are also coming in the next few years: https://blog.seagate.com/craftsman-ship/multi-actuator-techn... That will close the performance gap a bit too I suspect. I have to wonder about power consumption though.

Multi-actuator hard drives will not close any performance gap. They will just help slow the decline in IOPS/TB that higher capacity drives bring.

They accomplish this by essentially being multiple hard drives sharing a common spindle and helium-filled enclosure. As Seagate is currently implementing the idea, you still have only one head per platter, and at most one independently moving head per platter (but currently the stack of platters is just divided into two groups). Thus, sequential performance does not improve at all (and actually is reduced by the number of independent actuators), and random I/O increases by a small integer factor when the gap between hard drives and the slowest SSDs is already more than two orders of magnitude. However, power consumption shouldn't be much higher for this kind of multi-actuator hard drive over existing hard drive designs.

Re: 15TB HDDs: Western Digital Unveils the Ultrastar DC HC620

#90

Post by linker3000 »

bitL wrote: post #37
rootw0rm wrote: post #36

Earlier quoted context omitted.

before my current crop of 8TB WD reds, I ran Toshiba enterprise drives and they were extremely reliable for me. none of them failed in a 24x7 hardware raid6 environment after a few years. only replaced them to upgrade capacity.

I've read that Toshiba is based on old HGST process and those drives were extremely reliable, which is why I wanted to get them for the new Deep Learning workstation.

Correct (ex HGST employee). As part of one of the acquisitions/mergers, HGST divested a 3.5" production line to Toshiba.

https://www.tomshardware.com/news/wd-toshiba-hdd-hard-drive,...

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