Re: 3ware vs. MegaRAID

Jesper Krogh wrote:
> I've spent quite some hours googling today. Am I totally wrong if the:
> HP MSA-20/30/70 and Sun Oracle J4200's:
> https://shop.sun.com/store/product/53a01251-2fce-11dc-9482-080020a9ed93
> are of the same type just from "major" vendors.

Yes, those are the same type of implementation. Every vendor has their
own preferred way to handle port expansion, and most are somewhat scared
about discussing the whole thing now because EMC has a ridiculous patent
on the whole idea[1]. They all work the same from the user perspective,
albeit sometimes with their own particular daisy chaining rules.

> That would enable me to reuse the existing server and moving to something
> like Intel's X25-M 160GB disks with just a higher amount (25) in a
> MSA-70.

I guess, but note that several of us here consider Intel's SSDs
unsuitable for critical database use. There are some rare but not
impossible to encounter problems with its write caching implementation
that leave you exposed to database corruption if there's a nasty power
interruption. Can't get rid of the problem without destroying both
performance and longevity of the drive[2][3]. If you're going to deploy
something using those drives, please make sure you're using an
aggressive real-time backup scheme such as log shipping in order to
minimize your chance of catastrophic data loss.

[1] http://www.freepatentsonline.com/7624206.html
[2]
http://www.mysqlperformanceblog.com/2009/03/02/ssd-xfs-lvm-fsync-write-cache-barrier-and-lost-transactions/
[3]
http://petereisentraut.blogspot.com/2009/07/solid-state-drive-benchmarks-and-write.html

--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us