[dba-Tech] SSD Diagnoser

[Jim Lawrence]

I believe you are correct...sort of self-healing drives. But as I understand it there is a limit to how much a drive can self-repair...the more expensive the SSD the greater the limit.

Jim

----- Original Message -----
From: "John Colby" <jwcolby at gmail.com>
To: "Discussion of Hardware and Software issues" <dba-tech at databaseadvisors.com>, jwcolby at gmail.com
Sent: Tuesday, September 6, 2016 4:25:45 PM
Subject: Re: [dba-Tech] SSD Diagnoser

I have heard (can't swear to it) that even if there is a bad spot, the 
SSD internal controller will find it before it is completely 
non-functional, then move the data and mark the spot (sectors) bad.

So if you have a completely full (or very near full) drive, you may 
eventually have a real problem.  If not, then the unused areas will be 
used to hold the moved data if necessary.  I have also read that the 
SSDs have "wear leveling" algorithms which will spread the writes 
around.  Only writes are damaging to the SSDs.

If you think about it, any given cell can be written to about 2000 
times.  Most of a drive is used to store files.  Most files are written 
once and then sit there (unmoving) for the next 10 years. There are 
specific areas that get changed a lot (think an MDB file, or a swap 
file) but they are really few and far between.

One thing you do not want to do is run a defragger though.  Why? The SSD 
does not have to move heads so it is (almost) as fast to read fragments 
spread all over hell as it is to read a nice linear file.  And... the 
defragger reads that file that otherwise would not move for the next 10 
years and moves it intentionally to try and get it in fewer fragments.  
So the defragger causes wear that meant nothing in a rotating disk but 
which means a lot (or more anyway) in an SSD.

I can tell you that I have used SSDs in a raid 6 controller with active 
database usage for many MANY years and never had an issue.

As to your question, I have never seen a program which will "show you" 
wear happening on the SSD.

On 9/6/2016 10:51 AM, Rocky Smolin wrote:
> Dear List:
>
>   
>
> I upgraded my comp to an SSD about a year ago.  I've hears that they don't
> last forever and develop bad spots over time. I'm curious to know how this
> one is doing and to have a tool to monitor it from time to tie.
>
>   
>
> Any recommendations?
>
>   
>
> MTIA
>
>   
>
>   
>
> Rocky Smolin
>
> Beach Access Software
>
> 760-683-5777
>
>   <http://www.bchacc.com> www.bchacc.com
>
>   <http://www.e-z-mrp.com> www.e-z-mrp.com
>
> Skype: rocky.smolin
>
>   
>
>   
>
> _______________________________________________
> dba-Tech mailing list
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> Website: http://www.databaseadvisors.com
> .
>

-- 
John W. Colby

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