[mythtv-users] SSD disk for DB

[Douglas Wagner]

On Mon, Oct 8, 2012 at 4:23 PM, Jay Ashworth <jra at baylink.com> wrote:

> ----- Original Message -----
> > From: "Ronald Frazier" <ron at ronfrazier.net>
>
> > >What you have said above is true for Flash disks like SDHC,
> > > Compact Flash, etc but is not true for SSDs. These can be treated
> > > just like a normal hard disk.
> >
> > Not entire true. They are still subject to wear out, but due to wear
> > leveling you are talking about sectors going bad in years, rather than
> > flash drives, where in the pathological case you could see sectors
> > failing in just days. That said, you still do have to take some steps
> > to get the best life out of the drive.
>
> Nope: SSDs are made of *RAM*.  If you want them to retain anything at all
> they have to be battery backed.  And being made of RAM, they aren't subject
> to wear-leveling or anything; they don't wear any more than main memory
> does.
>
> In fact, unless you need a whole lot of ephemeral storage on a system
> where it's impractical to install it as main memory and make a ramdisk
> out of it, they have little justification -- especially at their price,
> which is uniformly pretty high.
>
> Cheers,
> -- jra
> --
> Jay R. Ashworth                  Baylink
> jra at baylink.com
> Designer                     The Things I Think                       RFC
> 2100
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No offence Jay, but you might want to check your source on this comment
since I FULLY believe you've got some misinformation here.

SSD's are not "made of RAM", they execute somewhat similar to RAM, yes,
since both are "solid state" but that's about as far as the similarities
extend.  While you are correct that 'RAM' is not subject to wear-leveling,
SSD's absolutely are subject to wear leveling...just like your flash drive
or USB stick is.

Re: Battery Backed...er...no.  You can power your system off, disconnect
your SSD Disk and carry it across country to your friend's house, plug it
back in and it will still have data...there's no "internal battery" that
will discharge on you in a few years and thus cause you to lose your data
when you power off or unplug your machine...the technology is VERY
different.

Regarding an in memory disk:  I'm going to jump out into an area I have
VERY LITTLE experience with and say:  You can't "store" your Myth TV
Database within a ramdisk.  The moment that machine goes off and/or needs
rebooted, that ramdisk is gone and so is whatever you've copied to
it...randisks are for TEMPORARY storage only (like /tmp).  There are things
you could do (upon startup say) to copy your MYSQL tables to a RAMDISK at
startup and then use them (you'd have to have some kind of system that
copies them back / syncs them periodically).  I have no idea how any of
this would work, but I suspect it's possible...still, SSD would be a much
"safer" method of working with any of this as an SSD is handled LIKE A
HARDDRIVE by the OS instead of like RAM.

--Doug
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