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  #46  
Old January 8th 19, 05:09 AM posted to alt.comp.os.windows-10
T
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Default SATA Drives

On 1/7/19 7:11 AM, Ken Blake wrote:

If you saw a device for which a 1.5 million hour MTBF was claimed,
would you believe it? If my arithmetic is right, 1.5 million hours is
over 160 years. How did they test it and determine that number?


That means if you place 1.5 million unit on a test bench,
one unit is predicted to fail in one hour. It is a pretty
useless figure
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  #47  
Old January 8th 19, 05:09 AM posted to alt.comp.os.windows-10
T
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On 1/7/19 8:30 AM, Jim H wrote:
On Sun, 6 Jan 2019 12:16:32 -0500, in
, Wolf K
wrote:

Seems to me that MTBF is testable, no assumptions required. I expect the
published figure(s) to summarise the test results. Where are the stats?



Testable how? Running one disk drive until it fails takes a long
time... and running many for a shorter time is expensive. Each winds
up giving a different figure for MTBF and both delay product
introduction if the product requires MTBF figures based on testing
before being introduced.

All of the above is why MTBF - at least for things expected to last a
loooong time - is CALCULATED (no actual testing involved) based on
knowledge of the design and the expected failure rate of its various
parts and subsystems.

The best use for MTBF data isn't to schedule when your hard drive
might need replacement before it fails... it's to determine (by
calculation) how many spares you need to keep in stock so a failed
drive in your large network can be replaced quickly.


Ignore MBTF and use warranty instead.
  #48  
Old January 8th 19, 05:42 AM posted to alt.comp.os.windows-10
nospam
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Default SATA Drives

In article , Mike
wrote:
https://www.networkworld.com/article...nking-ssd-myth
s.h
tml

"Exhaustive studies have shown that SSDs have an
annual failure rate of tenths of one percent,
while the AFRs for HDDs can run as high as 4 to 6 percent." ===
Boo!
and/or Hiss!


from that link,
And since SSDs contain billions of cells, we1re talking about an
enormous amount of data that can be written and deleted at every
moment of every day of the drive1s life. For example, one 100GB SSD
that offers 10 drive writes per day can support 1TB (terabyte) of
writing each and every single day, 365 days a year for five years.

very few people write a terabyte *every* *day*.


Help me with the math. Maybe this is a video surveillance system.
I get a new 100GB SSD and write 100GB to it. How many times did I erase
each cell?


stop thinking of individual cells.

100gb/day every day, based on the above statistic, would give you 50
years of expected life.

there have been endurance tests that hammered ssds (not a usual use
case), which lasted in the petabyte range, or around 25 years or so if
it was only 100g/day.

it's simply not worth worrying about.

nothing is perfect, so there's always the chance it might fail before
then, but it's almost certain to outlast any mechanical hard drive,
which could also fail at any time.

always have backups, no matter what option you choose.
  #49  
Old January 8th 19, 09:13 AM posted to alt.comp.os.windows-10
...w¡ñ§±¤ñ
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Default SATA Drives

"Ken Blake" wrote in message
...

If you saw a device for which a 1.5 million hour MTBF was claimed,
would you believe it? If my arithmetic is right, 1.5 million hours is
over 160 years. How did they test it and determine that number?


Not too much different than actuarial tables for mortality
Statistical analysis of error rates in a significant sample size tested over
a shorter period of time then used to generate a predicted outcome for a
mean population not the devices average or mean lifetime in the field of
use.

Hard drive manufacturers certainly haven't tested their products since
the mid-19th century(171 yrs ; 1.5MM hours). In the case of actuarial tables
one of the obvious error rates is death, just like a hard drive. In the
actuarial case having 171 yrs of data is relatively useless just like it
would be for a hard drive - the testers and testing equipment would all have
died before the 171 years of data collection.


....w¡ñ§±¤ñ
ms mvp windows 2007-2016, insider mvp 2016-2018

  #50  
Old January 8th 19, 10:40 AM posted to alt.comp.os.windows-10
Paul[_32_]
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Mike wrote:
On 1/7/2019 10:51 AM, nospam wrote:
In article , Paul
wrote:

https://www.networkworld.com/article...ng-ssd-myths.h

tml

"Exhaustive studies have shown that SSDs have an
annual failure rate of tenths of one percent,
while the AFRs for HDDs can run as high as 4 to 6 percent."
=== Boo!
and/or Hiss!


from that link,
And since SSDs contain billions of cells, we¹re talking about an
enormous amount of data that can be written and deleted at every
moment of every day of the drive¹s life. For example, one 100GB SSD
that offers 10 drive writes per day can support 1TB (terabyte) of
writing each and every single day, 365 days a year for five years.

very few people write a terabyte *every* *day*.


Help me with the math. Maybe this is a video surveillance system.
I get a new 100GB SSD and write 100GB to it. How many times did I erase
each cell?

over the next 2.4 hours, I overwrite all that data. How many times did
I erase each cell?

2.4 hours later, I have overwritten all that data. How many times did I
erase each cell?

Keep it up 10 drive writes per day.

.
.
.
.until it fails. What's the write amplification? How long did that take?

That's a limit case.
The other end is don't write it at all.
What's the shape of the life curve between those limits
based on size and number of writes and unused capacity on the drive
and how you TRIM it and and and...

I expect my spinner to be more or less independent of all that.
My SSD is a complex web of secrets hiding a fundamental defect
in the storage method that's getting worse with each generation
as geometries decrease and bits per cell increases.

Start up resource monitor and look at disk writes.
There are a LOT of writes due to system management. A LOT!
They may not be big writes, but if there's no available space,
my SSD has to move something to do it. All those small writes
may be amplified significantly when it comes to SSD erase cycles.
I don't have a number, but it does make me cautious.

In terms of actual bytes written by applications, my TV time shifter
writes about 30GB a day. I expect it would have to be TRIMmed frequently.
No idea how expensive a TRIM operation is in terms of erase cycles at
that level. I'm not anxious to put a SSD there.


Work some numbers. I just went through my "Sent" messages
for a table I'd copied out previously. I was hoping to
find the 545S table, but this is the table I got first.
Being a PRO model in name, the TBW might be higher than normal.

* Warrantied TBW for 860 PRO: 300 TBW for 256 GB model,
600 TBW for 512 GB model,
1,200 TBW for 1 TB model,
2,400 TBW for 2 TB model,
4,800 TBW for 4 TB model.

Write 100GB per day. Doing that for 10 days is "1 TBW".

The 300TBW drive will last 3000 days or 8.2 years.

The drive in question (a 256GB drive), would be using
about half its capacity. You are writing 100GB of it,
erasing it, writing 100GB the next day. It's a bulk writer
application.

The OS buffers in 64KB chunks, so as a rule
the OS doesn't tend to allow the "slow" write operation
to devolve into 4KB writes. I noticed this when using
a purposeful fragmentation app recently, that the OS didn't allow
a 4KB cluster drive to be written 4KB at a time. Because
that's bad for SSDs perhaps. Previous OSes would allow
a smaller "fragment" size. There seem to be two write
buffers. The "System Write Buffer" for when the destination
device falls behind (based on bandwidth). And a smaller
buffer at the C code level sort of, which does a tiny bit
of buffering in the name of "good SSD behavior".

You should still be able to use "sparse" file behavior if
you want, and the OS can't do anything about that. But
sparse writers are not common in software (pre-allocating
half the drive, and then writing to random 4KB locations -- it
takes brainz to do that and is not common). That's actually
a database pattern, rather than a surveillance camera pattern.

If you bought the 1TB drive, you get 1200 TBW and 32.8 years
of life before it has used all the wear life.

If you bought the 4TB model and wrote 100GB per day, it
lasts for 131.4 years.

TRIM would be part of the budget. Cells have to be erased
before they can be reused, and our hope is that TRIM is
a hint, and erasure only happens once rather than multiple
times. We don't care when the erasure is done - it either
gets done right on the TRIM hint, or, it gets done 10us
before the data is written, using the DRAM buffer in
the drive perhaps.

My assumption is you don't resort to pathological behavior.
For the 4TB drive, you don't put "3.9TB" of stale storage
filled up, then beat the **** out of the remaining 0.1TB
of space for years on end. If you did that, it would be like
owning a 128GB drive with only 150TBW and having time for
"only" 4.1 years of that pattern. You'd burn a hole in the
space at the end of the drive.

Drives have a small amount of overcapacity, so the 4TB drive
would have enough overcapacity to circulate enough spares
pool for 8 years of life. It would be up to the drive to
notice the large disparity on the blocks down at the end
and "move" the hot data area to other cells. I think that's
a definite possibility, that the drive will use active
wear leveling and actually waste a write moving some
of the stale content... every once in a while.

Since that's a Samsung drive, it's possible such a
decision is made every three months or so. A background
rewrite based on statistics. If something naughty has
been going on, the drive will attempt to smooth the
wear in an active way. Rewriting mushy cells. Giving an
opportunity to move the data around and smooth out
a hot spot. Now you're back to 100+ years of life.

This policy is proprietary, and two brands don't necessarily
handle pathology the same way. Passive wear leveling is
sufficient for non-pathological behavior. Active wear
leveling (drive CPU noodles out a strategy to make it happen
on an infrequent basis) is still a possible piece
of code in the drive. After the "mushy TLC" incident
Samsung had, this is likely to be a strategy for
their product. I don't know if other brands got the
hint from that bad PR and did the same or not. Firmware
is never going to be documented at that level.

Even if you bought a 256GB drive as a "movie" drive with
no "stale" storage on it, you still get a decent sized
roll of toilet paper. An 8 year roll of toilet paper.
Would a hard drive last for 8 years ? Of course.
But not all of them do. A few fail in 3 months.
A few fail in 2-3 years. Not many give the "golden"
performance of my 500GB drive. 43,817 hours. Not a
mark on it. Equivalent to 5 years continuous operation.
Will it last another 3 years ? Hard to say.

https://i.postimg.cc/rpJpKMTR/no-domino-flaws-here.gif

Paul
  #51  
Old January 8th 19, 11:44 AM posted to alt.comp.os.windows-10
Paul[_32_]
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Posts: 11,873
Default SATA Drives

T wrote:
On 1/7/19 7:11 AM, Ken Blake wrote:

If you saw a device for which a 1.5 million hour MTBF was claimed,
would you believe it? If my arithmetic is right, 1.5 million hours is
over 160 years. How did they test it and determine that number?


That means if you place 1.5 million unit on a test bench,
one unit is predicted to fail in one hour. It is a pretty
useless figure


Have you seen the size of the test chamber they use ? :-)

https://www.tomshardware.com/reviews...es,4408-3.html

Actually, the picture I was looking for, is missing. There's some
chamber they use for infant mortality, that runs the drive
for a short period of time. It had a big circular door on
the end, for once the chamber is loaded.

The WDC one seems to use a similar 6000 slot robot as Seagate.
I think the idea is, the robot can continue loading and unloading
slots, while the chamber stays at temperature.

https://www.tomshardware.com/picture...-tour.html#s38

https://img.purch.com/rc/600x450/aHR...FsaWJ1ci5qcGc=

I don't think any of that though, is life cycle testing.

They have at least 30,000 slots to hold product in
that one facility, so it'll take 50 hours before one fails :-)

Paul
  #52  
Old January 8th 19, 01:19 PM posted to alt.comp.os.windows-10
mechanic
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Default SATA Drives

On Mon, 7 Jan 2019 20:09:55 -0800, T wrote:

Ignore MBTF and use warranty instead.


As before, I merely reply to this to point to a spelling error.
  #53  
Old January 10th 19, 03:20 AM posted to alt.comp.os.windows-10
Paul[_32_]
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Default SATA Drives

Jim H wrote:
On Mon, 7 Jan 2019 20:09:55 -0800, in , T
wrote:

Ignore MBTF and use warranty instead.


Provided... that drives with a longer claimed warranty really last
longer. If they just cost more without lasting longer, then the mfgr
is just recouping his expected warranty cost at time of sale.

This is how some car batteries are marketed. If you compare two
batteries with the same ratings and one costs more and has a better
warranty, weigh them. If the more expensive longer warranty battery
isn't heavier, then you're paying for the warranty up front... and it
isn't worth it because the warranty is based on the original purchase
price while the cost of a new battery X years later has risen
considerably. They actually make a nice chunk of change on such
warranties.

In the case of hard drives, the prices for a same size replacement
seem to be dropping... provided that size is still available. Tried to
buy a 1 GB drive lately?


The warranty issue is "simple math". You work out the
price to provide the service, and add it to the price
of the drive.

On hard drives, your replacement drive is not a new drive.
It's a used drive that has been re-certified.

Maybe you're made to pay for shipping, to get it.

Then, there is the "serial number barrier" where you
enter the serial number into the web site, and magically,
the serial comes back as "bad". And the drive now has
no warranty. This happens more often than you'd think,
and would appear to be yet another scam.

It's one thing to not offer warranties on gray market
or shucked drives, but it appears perfectly valid
retail drives are getting the ole heave ho (#sn not valid).

Paul
  #54  
Old January 10th 19, 04:33 AM posted to alt.comp.os.windows-10
nospam
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Default SATA Drives

In article , Paul
wrote:


On hard drives, your replacement drive is not a new drive.
It's a used drive that has been re-certified.


because you sent in a used drive.

Maybe you're made to pay for shipping, to get it.

Then, there is the "serial number barrier" where you
enter the serial number into the web site, and magically,
the serial comes back as "bad". And the drive now has
no warranty. This happens more often than you'd think,
and would appear to be yet another scam.


it's not a scam. those are oem drives, which are warranted by the oem
(dell, lenovo, etc.), not the drive maker. contact the relevant
company.

It's one thing to not offer warranties on gray market
or shucked drives, but it appears perfectly valid
retail drives are getting the ole heave ho (#sn not valid).


they aren't.
  #55  
Old January 10th 19, 05:19 AM posted to alt.comp.os.windows-10
Tim[_10_]
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Posts: 249
Default SATA Drives

Paul wrote in :

Then, there is the "serial number barrier" where you
enter the serial number into the web site, and magically,
the serial comes back as "bad". And the drive now has
no warranty. This happens more often than you'd think,
and would appear to be yet another scam.

It's one thing to not offer warranties on gray market
or shucked drives, but it appears perfectly valid
retail drives are getting the ole heave ho (#sn not valid).

Paul

I had something similar happen. I had decided to try using an SSD for my
system drive, and picked up a highly rated Kingston with a three year
warranty. Just about at the two year mark, it bricked on me. I went to
request a warranty replacement, and was informed that Kinston had dropped
ALL support for that model a couple months earlier. So now I have a Samsung
EVO 350, and I watch the S.M.A.R.T and drive statistics data closely, and
image frequently.
  #56  
Old January 10th 19, 05:56 PM posted to alt.comp.os.windows-10
Ken Blake[_5_]
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Default SATA Drives

On Thu, 10 Jan 2019 01:46:57 +0000, Jim H
wrote:

On Mon, 7 Jan 2019 20:09:55 -0800, in , T
wrote:

Ignore MBTF and use warranty instead.


Provided... that drives with a longer claimed warranty really last
longer. If they just cost more without lasting longer, then the mfgr
is just recouping his expected warranty cost at time of sale.

This is how some car batteries are marketed. If you compare two
batteries with the same ratings and one costs more and has a better
warranty, weigh them. If the more expensive longer warranty battery
isn't heavier, then you're paying for the warranty up front... and it
isn't worth it because the warranty is based on the original purchase
price while the cost of a new battery X years later has risen
considerably. They actually make a nice chunk of change on such
warranties.

In the case of hard drives, the prices for a same size replacement
seem to be dropping...



Yes.



provided that size is still available. Tried to
buy a 1 GB drive lately?



No. Who would want to? It's so tiny as to be virtually useless. You
can buy 1GB thumb drives, but as far as I'm concerned, even those are
useless.
  #57  
Old March 2nd 19, 12:03 PM posted to alt.comp.os.windows-10
Lucifer
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Posts: 226
Default SATA Drives

On Fri, 4 Jan 2019 10:12:37 -0800, T wrote:

On 1/4/19 9:57 AM, Tim wrote:


Check your date. Its 2/3/19 today.

I plan on doing some cleaning and hopefully recabling on my PC. It is my
understanding that which SATA port a drive is plugged into does not matter.
Specifically, due to how the drives were added to my system, the SATA port
number does not bear any relation to the drive's position in the OS, i.e.
my system drive C: is plugged into SATA port 4, etc. I would like to
recable all the drives so port 1 is C:, port 2 is D:, and so forth. Am I
right in assuming this will make no difference to the system? I remember
way back in the day if a drive was plugged into a port other than the one
it was formatted on it was basically unusable until it was reformatted.


Hi Tim,

Yes and no.

A SATA drive will work on any port it is plugged into.

Check your motherboard manual. Some ports can be SATA II and
some can be SATA III. III is twice as fast. II's will
work in III slots and III's will work in II's slots, although
you will take a performance hit.

I like to put my main drive on port 0 and my DVD on port 1.
The rest I don't really care. Just a convention I follow.

Not what you asked, but SATA SSD drive are about 4 times faster than
mechanical drive and NVMe SSD drives are about 8 times as fast as
mechanical drives. If you go with SSD, make sure you spec out as much
empty space as used space to assist wear leveling. Also, Samsung
drives are the only high reliability drive I have come across. Stay
away from Intel.


I have a Sun Sunfire X2100 server which has two SATA hard drives.
I could not get drive 1 to work as a boot drive so I ended up using
drive 2. I wanted to use drive 1 as a storage drive but could not
get it to work that way either.
I theorised that the SATA controller was faulty. Fortunately the main
board has four SATA controllers so I switched drive 1 from SATA 1
to SATA 3. Now it works. Solaris 11 detected the drive on SATA 3
and uses it.

HTH,


Hi There Harry?

-T

  #58  
Old March 2nd 19, 02:34 PM posted to alt.comp.os.windows-10
mechanic
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Default SATA Drives

On Sat, 02 Mar 2019 22:03:42 +1100, Lucifer wrote:

Solaris 11 detected the drive on SATA 3
and uses it.


Respect!
  #59  
Old March 3rd 19, 09:05 AM posted to alt.comp.os.windows-10
T
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Posts: 4,600
Default SATA Drives

On 3/2/19 3:03 AM, Lucifer wrote:
HTH,

Hi There Harry?


You Funny Bunny! :-)
 




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