[mythtv-users] Another take on large-capacity disk enclosures

Brian Wood beww at beww.org
Mon Jun 15 22:08:00 UTC 2009

On Monday 15 June 2009 16:00:36 Yan Seiner wrote:

> Practical considerations:
> It takes a desktop-class system about 6-10 hours to check a 2 TB raid-5
> array.  You really don't want a single large array comprising of 20 1.5 TB
> drives; fsck would take weeks.
> If you pick your hardware right, you can get by much cheaper with esata +
> port multipliers at little to no performance penalty, especially if you
> design the wiring so that drives on the same port multiplier are in
> different logical groups.  Port multipliers come in 1x5 versions, so 4
> esata ports == 20 drives.  See the sata maillist for hardware that works.

I've heard that claim before, that using port multipliers will have little or 
no impact on performance. Is this because today's drives come nowhere close 
to the speed of the interface? 

Logically it would seem that there is no way to speed up the actual SATA port, 
so the theoretical max per port would have to be reduced by using 
multipliers, but if the drives were using far less than the port's 
theoretical speed it might work, so what is the practical limit to expansion 
without impacting drive performance?

Brian Wood
beww at beww.org

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