[mythtv-users] SSD disk for DB

[Simon Hobson]

Mike Perkins wrote:

>I would make the distinction here between a Flash disk and a Solid 
>State Disk (SSD). 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.

Well sort of.

An SSD is also subject to the same wear issues as other flash drive 
types - but the crucial difference is that they have wear levelling 
<stuff> built in. So while a flash drive (pen drive, SD card, etc) 
would wear out quickly if you write to the same blocks repeatedly, an 
SSD will automatically remap stuff internally to move those active 
blocks to less used physical storage. They also have spare blocks 
which are used both to improve performance (instead of waiting while 
a block is erased, just write the data on a spare block and update 
the map), and to deal with defects/aged cells.

So an SSD is still subject to wear, but the wear is automatically 
shared across all it's physical blocks - unlike flash drives where 
it's easy to wear out one block while still having plenty of life 
left in the rest of the drive.

As you say, SSDs haven't been out long enough to get much by way of 
real world feedback on durability yet.

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.