Re: How does OS-X behave with a dead SSD ?

From	joe <none@domain.invalid>
Newsgroups	comp.sys.mac.system
Subject	Re: How does OS-X behave with a dead SSD ?
Date	2016-11-30 07:55 -0600
Organization	Aioe.org NNTP Server
Message-ID	<o1mlo2$1i6g$1@gioia.aioe.org> (permalink)
References	(5 earlier) <291120161456080223%JimSGibson@gmail.com> <291120161828475976%nospam@nospam.invalid> <slrno3s8ou.1s71.g.kreme@snow.local> <ea6usbF9ovmU1@mid.individual.net> <583e6990$0$51650$c3e8da3$f6268168@news.astraweb.com>

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JF Mezei wrote:

> On 2016-11-29 22:20, Jolly Roger wrote:
<snip>> 
> You're assuming that you will notice it crapping out. Unlike  spinning
> rust discs, an SSD will continue to remain readable after writes become
> a problem.
> 

When writes are a problem, that should become apparent via SMART.

> But you may encounter a situation where after saving a document, the
> middle 4 blocks contain invalid data because the SSD was unable to write
> those 4 blocks and nobody noticed.
> 
The SSD would certainly notice. This would mean there are no free blocks 
available to put that data, inferring all excess/spare capacity has been 
consumed. SMART data will indicate there is a problem long before this happens.

> So unless you know how an SSD fails when cells cease to be writeable,
> and unless you know whether the OS notices it, you cannot state that
> you're perfectly safe,

Once YOU consider YOUR situation only YOU can determine how safe YOU are. 
The first thing to consider is the endurance of YOUR drive, then compare
that to how much data YOU write in a month. Then you can determine the 
expected life YOU might see. Then, combined with backups YOU do, YOU can 
determine how safe YOU are. YOUR expected life can me 10s or 100s of years.

At that point, your concerns are truly FUD.

> 
> 
> This isn't FUD, It is just about understanding how SSDs fail. It is a
> different tech from spinning rust drives and behaves very differently
> internally using very proprietary and undocumented logic so each SSD may
> be failing in different ways.

As you admit, each SSD can fail in different ways. So how do you expect
anyone to tell you what might happen with whatever SSD you have under your
specific conditions. 

Can you tell us how the version of OS you will be running whenever that SDD
happens to fail actually behaves when an SSD fails. That code has probably
not been written. (If you expect the SSD to fail in 2025, what OS will you 
be running and how do you think it will behave.)

> 
> If you don't even know that an SSD will report unwriteable cells in
> SMART data, how can you be sure that your current SSD hasn't begun to
> degrade and lose cells ?

If YOU use the SMART tools designed for YOUR SSD, then YOU should get a 
valid picture of the drive. There may not be a field that is called
"unwriteable cells" but other fields will tell you something.

It is up to YOU to understand YOUR SSD and determine what YOUR risks are.
We cannot say anything useful without know YOUR details. So for all intent
and purpose, your queries are nothing more than an expression of your FUD.

Show us the details mentioned above and your calculations of expected lifetime 
in your situation and we may be able to contribute.

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Thread

How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-27 14:55 -0500
  Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-27 20:07 +0000
    Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-27 20:18 -0500
      Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-27 20:32 -0500
        Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-27 20:54 -0500
          Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-27 20:56 -0500
            Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 02:09 +0000
          Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 02:05 +0000
            Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-27 23:36 -0500
              Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-28 07:31 -0500
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-28 13:41 -0500
                Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-28 14:32 -0500
                Re: How does OS-X behave with a dead SSD ? android <here@there.was> - 2016-11-28 21:05 +0100
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 20:39 +0000
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-28 18:52 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 23:56 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-11-28 19:06 -0500
                Re: How does OS-X behave with a dead SSD ? joe <none@domain.invalid> - 2016-11-28 19:53 -0600
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-28 18:30 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 20:38 +0000
              Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 20:37 +0000
      Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-28 01:47 +0000
      Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-11-28 06:31 +0000
        Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-28 02:07 -0500
          Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-11-29 01:40 +0000
          Re: How does OS-X behave with a dead SSD ? Jim Gibson <JimSGibson@gmail.com> - 2016-11-29 14:56 -0800
            Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-29 18:28 -0500
              Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-11-30 00:52 +0000
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-30 03:20 +0000
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-30 00:54 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-11-30 07:19 +0000
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-30 16:38 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-01 00:44 +0000
                Re: How does OS-X behave with a dead SSD ? joe <none@domain.invalid> - 2016-11-30 21:11 -0600
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-01 03:34 +0000
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-01 12:55 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-01 16:51 -0500
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-01 18:46 -0500
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-01 19:37 -0500
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-02 00:46 -0500
                Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-12-02 01:42 -0500
                Re: How does OS-X behave with a dead SSD ? Jim Gibson <JimSGibson@gmail.com> - 2016-12-02 01:04 -0800
                Re: How does OS-X behave with a dead SSD ? joe <none@domain.invalid> - 2016-12-02 08:06 -0600
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-03 08:50 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-03 15:07 +0000
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-03 15:16 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-03 10:57 -0500
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-03 17:06 -0500
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-03 17:25 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-04 00:32 +0000
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-03 21:19 -0500
                Re: How does OS-X behave with a dead SSD ? David Ritz <dritz@mindspring.com> - 2016-12-03 21:39 -0600
                Re: How does OS-X behave with a dead SSD ? joe <none@domain.invalid> - 2016-12-03 19:41 -0600
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-03 21:26 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-04 05:59 +0000
                Re: How does OS-X behave with a dead SSD ? ANTant@zimage.com (Ant) - 2016-12-04 21:48 -0600
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-05 18:01 +0000
                Re: How does OS-X behave with a dead SSD ? ANTant@zimage.com (Ant) - 2016-12-05 22:17 -0600
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-03 10:51 -0500
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-02 10:28 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Browne <alan.browne@freelunchvideotron.ca> - 2016-12-03 08:48 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-03 15:02 +0000
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-02 17:54 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Baker <alangbaker@telus.net> - 2016-12-05 00:08 -0800
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-05 16:10 +0000
                Re: How does OS-X behave with a dead SSD ? Alan Baker <alangbaker@telus.net> - 2016-12-05 12:47 -0800
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-05 21:53 +0000
                Re: How does OS-X behave with a dead SSD ? joe <none@domain.invalid> - 2016-11-30 07:55 -0600
                Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-30 11:12 -0500
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-11-30 16:44 -0500
                Re: How does OS-X behave with a dead SSD ? nospam <nospam@nospam.invalid> - 2016-11-30 17:14 -0500
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-01 00:53 +0000
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-01 12:58 +0000
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-11-30 20:15 +0000
                Re: How does OS-X behave with a dead SSD ? billy@MIX.COM - 2016-12-04 05:25 +0000
                Re: How does OS-X behave with a dead SSD ? Jolly Roger <jollyroger@pobox.com> - 2016-12-04 06:02 +0000
                Re: How does OS-X behave with a dead SSD ? JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-12-04 02:00 -0500
                Re: How does OS-X behave with a dead SSD ? Lewis <g.kreme@gmail.com.dontsendmecopies> - 2016-12-04 18:42 +0000
              Re: How does OS-X behave with a dead SSD ? Jim Gibson <JimSGibson@gmail.com> - 2016-11-29 18:10 -0800

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