
14TB Hard Drives Now Available - nla
https://www.anandtech.com/show/11901/western-digital-now-shipping-14tb-hgst-ultrastar-hs14
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loeg
SMR drives can be thought of as tape libraries. You have a bunch of large,
independent tapes that can all be written sequentially. But you can't do
random writes to the tape. (SMR drives also have a lower density, non-SMR
"scratch region" that can be used for metadata, or to build up to a larger I/O
piecemeal. My metaphor is breaking down here.)

They're not generally useful for the kinds of applications harddrives are
classically used for (classic filesystems). They're mostly useful for
applications that already use tape, with the benefit of much quicker random
reads.

Log filesystems may be able to take advantage of them. There will necessarily
be I/O overhead to garbage collect deleted files out of SMR regions. (Because
you have to rewrite the entire SMR region to compact.)

Is anyone using or planning to use SMR drives in production? If you're able to
share, I'd be curious to learn about your use case and how you plan to make
efficient use of the disk.

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phil21
I use a bunch of 8TB SMR Seagate Archive drives in a ZFS pool for backups and
media storage.

I run ZoL, and honestly they've surprisingly been relatively solid drives. You
can expect roughly 10-15MB/sec or so write throughput per drive, and latency
is of course pretty bad. Across 24 spindles though, I haven't had too many
complaints - it's archival storage and reads are fast enough for most use
cases - about 50-70MB/spindle sustained for large files.

I would not try to say rsync millions of tiny files against this pool - it
would not hold up well. However for it's use case - write large files
once/read occasionally I'm quite happy - I just wish price would have come
down over the course of 2 years as I had originally expected. You can expect
to pay $200-220/drive even today, and that's what I paid the first batch when
starting my pool.

Out of 24 total spindles I had 2 early failures (within 120 days of install)
but otherwise no other failures. These drives were replaced hassle free via
RMA. My I/O pattern is pretty light - probably 100GB written per day across 24
spindles, and maybe 1TB read.

Basically if you try to do anything but streaming writes you're going to have
a bad time. They are a bit more forgiving on the read side of the fence
however. Don't expect these things to break any sort of speed records!

If I were buying today I wouldn't buy 8TB SMR - I'd pay the $20-30/spindle
premium for standard drives. I'd have to look at the 14TB costs to see if the
huge speed tradeoff would be worth it. When I first started using them, the
cost per GB was compelling enough to give it a shot and I'm pretty happy with
the results.

~~~
mozumder
What do you need to do to get FreeBSD to use SMR drives properly with ZFS? Are
there special drivers?

It seems ideal for a write-once/read-many media server.

~~~
phil21
These are drive-managed SMR, so no special drivers needed. I agree they are
ideal for write-once/read-many media servers :)

Today I'm not sure the 8TB drives make any sense as prices have come down so
far on regular 5400rpm slower drives that are _much_ faster. These new 14TB
spindles will be interesting to keep an eye on.

I imagine SMR won't really take off, if it does I'd expect more direct
kernel/driver support for the hardware. Drive-managed SMR is always going to
be exceedingly inefficient.

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white-flame
I bought an 8TB shingled drive. While the initial hundreds of MB of backup
files wrote at reasonable speeds, it quickly dropped down to 4-5MB/sec
sustained average for the rest, until it was idle for hours to catch up. Host
management probably can help, but I'm not touching another SMR drive again.

~~~
ioquatix
I guess if you use these for a log-style database, write only backup (e.g. a
replacement for tapes with better random read), you'll be happy. But for a
general purpose drive they suck.

~~~
white-flame
What I was doing was large backups, no overwriting, and it slowed down
massively. I reformatted to a linear log filesystem, and still had the same
unusable performance trend. However, since the drive was already somewhat
used, and the drive itself knows nothing about the filesystem but only about
sectors, I'm sure it was shuffling all the old data around as well.

Strangely enough, I could imagine it might work for a primary hard drive, as
writes tend to be small and bursty allowing the SMR shuffling to catch up. But
installation would take days.

Marketing them as "Archive" drives as Seagate did is the absolute wrong case
for these. It's impossible to get any backup/archive copied over in any timely
fashion. As a live mirror which gets piecemeal changes as they happen, then
maybe. But that's still not an "archive".

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mynewtb
> since the drive was already somewhat used

You are spreading a lot of FUD based on one single anecdote with a used drive.
Let me counter that anecdote with my own complete satisfaction of using such
drive for over a year of daily backups without anything 'taking days'.

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Dylan16807
Why does it matter that the drive was used? If I can permanently damage my
performance by using a different filesystem for a while, that's a big deal.
It's not FUD to talk about how drive-managed SMR is unpredictable, and might
work great or might work horribly, and you can't entirely predict what you'll
get.

~~~
mynewtb
Why should filesystem specifics matter to the device itself? If you believe
that is the case, did you rewrite the whole drive with zeros or something, or
better yet use some device builtin erase function?

~~~
Dylan16807
> Why should filesystem specifics matter to the device itself?

I agree! That's why I think "drive was used" should not be a disqualifier for
seeing horrible performance. Why should a former filesystem matter?

> did you rewrite

Not my drive.

~~~
mynewtb
A used drive might have been treated badly, have thousands of online hours etc

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aembleton
"2.5 million hours MTBF"

How do they calculate that? That works out as 285 years!

Half of these drives will last 285 years of constant operation. I find that
hard to believe.

~~~
jsmthrowaway
It’s predicted statistical failure rate in aggregate for the drive model. Two
drives running for 24 hours is 48 hours for MTBF purposes, so scale MTBF by
the number of drives. 1,000 drives would expect to have one failure per 104
days. 10,000 drives would expect to have one failure about every week and a
half. It’s not “half these drives will run 2.5 million hours.” I agree, the
“mean” is confusing until you know that. It also doesn’t predict low
quantities well, including 1, for obvious reasons. The larger the quantity
gets, the better the prediction tends to get IME. Backblaze has published work
on this.

Failure rate is also independent of lifetime. Drives have other measurements
for lifetime.

~~~
yosito
So, in layman's terms, if I buy two of these and mirror them is it a pretty
safe bet they'll last my whole life?

~~~
jsmthrowaway
No, because design lifetime is distinct from failure rate. Failure rate is
just that: a predicted _rate_ of _failure_ (not lifetime) in aggregate for a
model within design lifetime. Beyond lifetime, all bets are off. Think of this
MTBF as saying “your two drives probably won’t fail within lifetime. A
significant number of your 10,000 will.”

Regarding longevity, often the predicted lifetime of a drive is close to its
warranty. You will sometimes experience no issues exceeding design lifetime,
and sometimes drives immediately explode. I’ve seen both, from four-year
lifetime drives entering year 13 in continuous service to other drives buying
the farm one day after lifetime and SMART wear indicator is fired.

As drives age, mechanical disruption becomes a much bigger deal. That rack of
13-year drives is probably one earthquake or heavy walker away from completely
dead in every U. Even power loss, including from regular shutdown, will
probably permanently end the drive when they’re far beyond lifetime. That’s
the danger in a 24x7 server setting if you’re not monitoring SMART wear
indicators (even if you are, really); power cycling your rack can, and does,
trigger multiple hardware failures. All the time. If all the drives in it were
from the same batch, installed at the same time, and an equal amount past
lifetime, it’s _very_ possible for the whole rack to fail when cycled — I have
actually heard of this happening, once.

MTBF is unexpected failure. Design lifetime is expected failure.

~~~
DamonHD
I've had a nice rack of discs, though small by today's standards, AFAIK well
within any MTBF, wrecked when some junior decided to see what the phased
shutdown button in the machine room did during the middle of the bank's
trading day, cutting off half the power to my cabinet at one point, which SCSI
doesn't protect against.

There's always events dear boy, events!

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dmitrygr
Does Linux kernel have the code to manage these SMR drives as they need to be?
(Seems like HGST purposefully left that to the OS to do - imho a smart choice)

~~~
wmf
Here's the recent-ish status:
[http://events.linuxfoundation.org/sites/events/files/slides/...](http://events.linuxfoundation.org/sites/events/files/slides/lemoal-
Linux-SMR-vault-2017.pdf)

Looks like F2FS should work as of Linux 4.10.

~~~
loeg
See slide 21 — F2FS garbage collection after file/directory deletion is _very_
expensive compared to classical filesystems on conventional disks.

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tempestn
If you want a reasonably massive HDD for (relatively) cheap that's usable in
general purpose applications, the Seagate Ironwolf is starting to look pretty
good. Their 10TB drive has been hovering around the same $/TB as an average
4TB lately.

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dghughes
I'm curious why helium would be used instead of a vacuum. I can imagine a
vacuum would be difficult to maintain but would it be any worse than
preventing helium from leaking out?

Helium is rare and critical for research and MRI machines it seems wasteful to
use it in hard drives.

~~~
ykler
Hard drives need a gas because the heads use it to float over the platter. And
helium is hardly that rare that it is an issue; it is used in balloons for
children.

~~~
lamynator
Helium used for balloons is low grade helium that has already been recovered
from another process. Medical grade helium is virtually pure helium and that
is in short supply. Question whether this HDD needs pure or low grade.

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mentos
My hesitation to a drive this large is that you stand to lose that much more
in a failure?

~~~
dsr_
You are expected to deploy these in very large RAIDs or similar protection
schemes.

They are terrible as single disks, or even in small arrays. Think of them as
an alternative to tapes.

------
known
And 14TB RAM in future

