Can a CPU bottleneck FreeNAS R/W performance?

[tfran1990]

i just watched this youtube video
https://www.youtube.com/watch?v=GGd-DiDnLpw does this guy know what he is talking about? i seen that he just built a NAS. Is what he saying true about storage? Are there some things that are not taken into consideration when he is "testing"? does this bottleneck only happen with more or less disc?

oh and he built a NAS without ECC memory...

 

[m0nkey_]

As soon as this guy starting talking cache, they he lost all credibility. He failed to explain when you would need a SLOG or L2ARC. A SLOG is only useful with synchronous writes, L2ARC will use RAM, so unless you have 64GB RAM or more an L2ARC is just going to cause headaches.

If he's got a pretty average CPU, along with the fact he's using 10GbE of course things are going to bottleneck.

If you're an average user, then gigabit and read/write performance will do fine even with the cheaper Intel Pentium CPUs.

 

[tfran1990]

As soon as this guy starting talking cache, they he lost all credibility. He failed to explain when you would need a SLOG or L2ARC. A SLOG is only useful with synchronous writes, L2ARC will use RAM, so unless you have 64GB RAM or more an L2ARC is just going to cause headaches.

If he's got a pretty average CPU, along with the fact he's using 10GbE of course things are going to bottleneck.

If you're an average user, then gigabit and read/write performance will do fine even with the cheaper Intel Pentium CPUs.

he was rocking an i3 61000
i want to look into what SLOG and L2ARC is can you point me to a clear(noob guide) expiation?
Also i have some questions about starting out with smaller fewer drives, then maybe getting more bigger drives later. how does freenas handle the upgrade of drives? take one offline at a time and have them rebuild one by one?

 

[danb35]

i want to look into what SLOG and L2ARC is can you point me to a clear(noob guide) expiation?

http://www.freenas.org/blog/zfs-zil-and-slog-demystified/
http://www.45drives.com/wiki/index.php?title=FreeNAS_-_What_is_ZIL_&_L2ARC

how does freenas handle the upgrade of drives? take one offline at a time and have them rebuild one by one?

http://doc.freenas.org/11/storage.html#replacing-drives-to-grow-a-zfs-pool

 

[tfran1990]

thank you so much. i might as well read the UNCLE FESTERS GUIDE while im at it.

 

[Chris Moore]

does this guy know what he is talking about?

He had some serious problems with his testing methods.

 

[tfran1990]

He had some serious problems with his testing methods.

what exactly should i look out for?

 

[Chris Moore]

what exactly should i look out for?

The big problem with his testing is the number of drives. With that few drives, almost any configuration you can come up with will perform about the same. More drives is faster.

 

[Waco]

Long story short, no, he doesn't really know what he's doing. SLOG/ZIL, L2ARC, etc...just don't bother with them. They're good for very specific use cases that almost *nobody* at home cares about. I'm a storage fanatic with a day job of designing/administering ~hundred petabyte storage systems and even I have trouble coming up with use cases for those features. Even my DB2 databases don't use them...

But yes, CPUs can absolutely bottleneck performance. Just like disks. Just like SATA/SAS controllers. Just like PCIe lanes. Just like memory bandwidth. Etc...