[mythtv-users] What is best filesystem for recordings?

[Warpme]

On 02/07/15 09:22, Andre Newman wrote:
> I was also concerned as to what will happen if the power fails in the middle of one of these read modify write operations, some(most?) SSDs have backup capacitors to keep things going for long enough but I doubt that’s possible for a mechanical drive! There seems to be a potential for a lot of corrupted tracks.
I think it is possible also for mechanical drive. Spindle will go OK for 
few msec by kinetic energy.
On drive capacitors energy must be sufficient to allow park disk heads 
in parking zone - and energy needed by heads servomechanism is for sure 
bigger than energy needed to finishing in-progress writing.
For SMT, writing process is little more complicated as it include 
rewrite side tracks. I believe producers need to introduce high level of 
interleave to minimize data loss in case when power goes down during 
rewrite sequence.
It is simple trade-off: write speed<->resiliency for power off.
As interleaving goes up (for resiliency) - speed of rewrite goes down.
Tests results showing temporarily write speed 0 means high level of 
interleaving.
All this is valid only for drive managed version of SMT (see below).
Host managed HDDs are fullt prone for power loss in the same level like 
RAM based disk caches (those without battery backup)
> I had some vague recollection of driver/OS support being needed, I must have read the same article.
I believe there are 2 types of SMR drives:
1.drive managed
2.host managed

Seagate Archive is drive managed - so all rewrite is managed internally 
by drive and totally hidden from external world.
+ is on any requirement from OS
- is unpredictable write speed

For host managed drives - there is strict requirement how OS is doing 
write operation on drive.
AFIK basic requirement is to do sequential write for defined group of 
sectors on drive.
For doing this OS must be aware of SMR drive (things like CHS-like 
geometry, etc) and OS - when writing even single sector - must take into 
account whole algorithm about to read-then-write into defined HDD portions.

+ is high and predictable speed
- is OS SMR awareness & support need.