[mythtv-users] SSD disk for DB

[Joseph Fry]

>  > >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.
>
>
> 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.
>

Actually you are both right and wrong.  Any storage media based on solid
state storage would be considered an SSD.  There are definitely SSD's based
on volatile memory coupled with a battery to preserve data during reboots
and short outages, however they are generally only used in special
applications.  These days its rare to hear someone talk about that type of
SSD in the context of consumer products.
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