[OSM-dev] Table/Index Access (for SSD)

Frederik Ramm frederik at remote.org
Tue Jun 19 22:33:43 BST 2012


Hi,

On 19.06.2012 19:17, Martin Koppenhoefer wrote:
> would you recommend ext4 also for standard HDs? Is it useful to
> enable/disable journaling (speed vs. safety)? Or is postgres caring
> for integrity if there is a problem like an unexpected power down
> (transaction integrity)? Or am I confusing HD integrity with db
> integrity?

With fsync=off I believe that any unexpected power-down is likely to 
ruin your database anyway, so my recommendation would be to have a 
fallback if that happens ;)

With fsync=on and a journalling file system you could be safe from that 
for a small penalty in performance (I guess around 10%).

Reason I use ext4 on the SSD is that it supports TRIM (-o discard) which 
is generally recommended for SSDs. People say that SSD performance 
deteriorates faster without TRIM. But to be honest, I'm just following 
Internet recommendations here and don't have long-term benchmarks.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"



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