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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

#91

Post by tracker1 »

chrisper wrote: post #2

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

Depends... my NAS is mostly used for video/audio archives and generally only one device in the house using it, playing back a single file, or listing a directory. Would probably be fine in that use case. Beyond that, it's used for backups.

Seems like a decent use case. I'm not sure how well they'd work in a NAS with Raid-5/6 though. I'd been considering a new nas with 4-6 drives at 8-12TB already. Random I/O isn't my primary use, and I'm sure there are others at these sizes.

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

#92

Post by tracker1 »

nine_k wrote: post #24
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.

RAID6 should be fine rebuilding online (in RAID5 mode) even under a moderate write load. Of course one should source RAID disks form 3 different vendors, to ensure that they are from different batches, and are not going to fail at approximately the same time.

Good advice, though I once had about half a dozen drives (12 drive RAID Z2 with 2 as hot spares) fail within a few weeks of each other in separate batches from sourcing. (Seagate 3TB drives, I think there's been articles on how bad that series was).

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

#93

Post by fencepost »

peterburkimsher wrote: post #54
worldexplorer wrote: post #38

Earlier quoted context omitted.

How do people use such large HDDs when internet download speeds are still low as compared to downloading directly on cloud services (like aws)?

Internet speeds are slow in some places, such as France (specifically the Pays de Gex near Geneva, where my parents live). My dad uses iCloud, but he drives to CERN to upload (he just retired). I have 18 TB: 5 TB Seagate (x2), 4 TB WesternDigital, 2 TB WesternDigital, and 2 TB internal. Backups take the most space - I fix laptops for friends from church, and they don't back up but still want their files to be safe. I…

I'm going to highly recommend looking at drives with WizTree, which does a very fast display of what's taking up space based on parsing the MFT rather than scanning the entire drive.

You may find that there's a massive amount of data where you wouldn't expect it, such as in the Windows Temp directory - if so and it's a bunch of files named "cab_something", you can kill all of those and prevent recurrence with a little housekeeping.

Details: https://www.computerworld.com/article/3112358/microsoft-wind... (update log files in windows\logs\cbs get auto-compressed, but compression breaks and leaves big temp files if the file to compress >2GB)

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

#94

Post by pinewurst »

kdkeyser wrote: post #87
jmpman wrote: post #47

Earlier quoted context omitted.

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 10…

GridRAID is owned by Cray now, who were the primary OEM from Seagate.

Thanks for pointing out that declustered/distributed rebuild RAID has many historical precedents (also 3PAR BTW) pre-CRUSH/Ceph.

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

#95

Post by newman314 »

cm2187 wrote: post #59
wtallis wrote: post #55

Earlier quoted context omitted.

I'm curious who sold you a NAS with SSD caching that didn't support bypassing the cache for sequential I/O. That's a pretty basic and obvious feature, and it seems like the manufacturer must not have been taking their SSD caching feature seriously if they didn't implement bypassing.

Synology.

Synology has NVMe SSD caching in recent models but it's an either or situation with 10G. I'm holding out for a Synology model with both.

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

#96

Post by marmaduke »

kdkeyser wrote: post #81
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,…

I have a bunch of services running off a 8 12 TB IronWolf Pro array in RAID10, and it does pretty well, even for DB stuff.

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

#98

Post by antongribok »

kdkeyser wrote: post #83
mjevans wrote: post #60

Earlier quoted context omitted.

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 ve…

It's not accurate to say that BlueStore is just a large RocksDB...

RocksDB is one of several possible backends for object maps. There is a lot more to BlueStore than just omaps.

Also, BlueStore was actually designed with SMR drives in mind, however certain components of it are best placed on solid state media.

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

#99

Post by lostapathy »

thfuran wrote: post #41
stephengillie wrote: post #32

Earlier quoted context omitted.

Do other manufacturers produce this size of drive? It's difficult to source from 3 vendors if there's only one making the product.

Get one from amazon, one from newegg, one from the manufacturer directly or some such.

I try to buy hot spare or the last drive in a raid6 later than the rest of the array to try to spread them out too.

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

#100

Post by Dylan16807 »

quasarj wrote: post #97

So does anyone know of a way to take a set of files and write them to an HDD, in NTFS or exFAT format, in a single sequential write? Essentially building the FS on-the-fly (because we're talking about datsets that are much too large to fit into memory)?

So basically a zip file?

I will note that you could easily build the MFT before you start transferring data. That's really your active 'dataset' here, and it's not very big.

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