On Mon, 2011-07-18 at 11:53 +0100, Tom De Mulder wrote: > On Sun, 17 Jul 2011, Lutz Vieweg wrote: > > > What is really an important factor for SSD performance: The controller. > > The same SSDs perform with significantly lower latency for us when > > connected to SATA controller channels than when connected to SAS > > controllers (and they perform abysmal when used as hardware-RAID > > constituents, in comparison). > > Interesting. > > I think it depends a lot on the controller. On a Dell server with PERC5/i > RAID controller (actually made by LSI) I saw some performance degradation > but not enough that I'd consider it a deal-breaker for situations where I > really cared about the RAID functionality, more than about the loss of > performance. After all, the latency is still massively lower than it is > with spinning disk. > > I have a really great Areca RAID controller in a different server, but > unfortunately it's in use and it'll be a while before I get another one I > can use for testing. Given how well it does in other respects, I have high > hopes for it. I agree that the controller can influence performance: 1. SATA controller: direct communication 2. SAS controller: Serial ATA Tunneling Protocol (STP) is used, this can have an impact on performance 3. Hardware RAID controller: depending on the controller, performance impact can be from low to very high Regards, Werner > > > Best, > > -- > Tom De Mulder <tdm27@xxxxxxxxx> - Cambridge University Computing Service > +44 1223 3 31843 - New Museums Site, Pembroke Street, Cambridge CB2 3QH > -> 18/07/2011 : The Moon is Waning Gibbous (83% of Full) > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- : Werner Fischer : Technology Specialist : Thomas-Krenn.AG | The server-experts : http://www.thomas-krenn.com | http://www.thomas-krenn.com/wiki -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
