XLog vs SSD [Was: Re: random write in xlog?] - Mailing list pgsql-hackers

From James Cloos
Subject XLog vs SSD [Was: Re: random write in xlog?]
Date
Msg-id m3d3pcyqa9.fsf_-_@jhcloos.com
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In response to Re: random write in xlog?  (Jeff Janes <jeff.janes@gmail.com>)
Responses Re: XLog vs SSD [Was: Re: random write in xlog?]  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-hackers
>>>>> "JJ" == Jeff Janes <jeff.janes@gmail.com> writes:

JJ> Anyway, the writes are logically sequentially, but not physically.
JJ> If I remember correctly, it always writes out full blocks, even if
JJ> the last part of the block has not yet been filled with new data.
JJ> When the remainder gets filled, it then writes out the full block
JJ> again, both the already written and the new part.

What does that mean for use of a flash SSD for the xlog dir?

Does the block writing mesh up well with the usage pattern a flash
SSD needs to maximize lifespan?

I'd love a dram ssd for pg_xlog and the journals for the other
filesystems, but they cost too much.

-JimC
-- 
James Cloos <cloos@jhcloos.com>         OpenPGP: 1024D/ED7DAEA6


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