[mythtv-users] Adding an SSD to my MBE -- partitioning question

Ronald Frazier ron at ronfrazier.net
Mon Feb 13 20:49:42 UTC 2012


On Mon, Feb 13, 2012 at 10:30 AM, Mark Lord <mythtv at rtr.ca> wrote:
> Your mechanical drives will be long dead and replaced at least once or twice
> before you ever wear out a modern SSD (assuming the SSD doesn't hold recordings).

Not necessarily true. As I documented in my recent SSD thread, the
writing that myth does to temp every time the scheduler runs (several
times per hour) was writing over 30GB/day to the drive for me. At that
rate, I was going to run through the rated usable life of the drive in
3 to 4 years (rated for 20GB/day for 5 years). Now I realize this
isn't an exact lifetime rating (obviously they are going to have some
padding in there, and some of it depends on how utilized the drive is,
etc), but it's certainly not a limitation I would choose to push up
against. And since (as my other thread discussed) moving either /tmp
or mysql's temp location into RAM is actually quite easy, I see no
reason to push the boundaries and test just how close their ratings
are to actuality.

> Most important thing to do:  ensure each partition on the SSD is aligned to
> an even power of two.  Eg. partition-1 should start at sector 64,
> rather than the (old) default of sector 63.

Many websites I saw suggest aligning to the erase block boundary
rather than the page boundary. I've seen other websites saying that's
not necessary and to me it seems that page alignment should be
sufficient, but I can't be certain there's not something beyond what I
know that would have an effect. However, since you would be talking
about wasting at most a few MB of disk space, I figured that was
trivial and thus played it safe by going with the erase block
alignment. Unfortunately that varies from drive to drive, and it isn't
always published data. On my old Gen 1 Intel X-25M it was believed to
be 512KB. I played it safe and went for 1MB alignment. I believe I've
read the newer intel 320 series drives use a 2MB erase block size.
I've also read that Windows Vista and 7 always align to a 1MB
boundary, though I've never checked it personally.

So take that for what it's worth :)



> And no need to bother with a separate /boot partition.

Agreed. I've got everything except my mass-storage files (audio,
video, photos, and backups) and /tmp running off the SSD. Mass-storage
is on regular hard drives, and /tmp is in RAM (tmpfs).


-- 
Ron Frazier


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