RAID Card bottlenecking SSDs?

SimpleNode

I've read in many places that most RAID Cards are bottlenecks when used in a RAID10 SSD array (what I'll be using them for). While I'm not sure what RAID cards Incero uses, do most 4 port cards bottleneck these arrays?

Would I be better off using mdadm?

AsadHaider

It would depend on the RAID controller I guess.

Damian

One of the newer-generation RAID cards shouldn't be the bottleneck, such as an LSI 9266: http://www.lsi.com/channel/products/storagecomponents/Pages/MegaRAIDSAS9266-8i.aspx

I would say that using mdadm wouldn't cause you a bottleneck, it would just grind the rest of the system to a halt to process i/o.

Kenshin

PCI-E 2.0 x8 tops at 1.5-2G depending on what RAID card you use. This is effectively 4x RAID0 SSD or 8x RAID10 SSD. LSI 9265/9266 high recommended to hit 2GB/sec. If you can afford it, the newer PCI-E 3.0 x8 cards are floating around, these are suppose to be able to achieve higher speeds but the drivers will be a pain since it's not integrated in current kernels yet, 9265/9266 and below are suppose to be already in stock RHEL kernels.

Mirroring should be done on the RAID card because it'll only use the SATA/SAS interface bandwidth and not PCI-E. OS sends 1 copy to RAID card via PCI-E bus, RAID card sends 2 copies to 2 SSDs. This is a good reason not to do RAID1/RAID10 on mdadm.

mdadm isn't a bottleneck, works perfectly fine for RAID0. Based on my tests mdadm outperforms a LSI 9240 slightly, effectively a cache-less raid card.

Nick_A

@SimpleNode said: do most 4 port cards bottleneck these arrays?

No

SimpleNode

@Nick_A o_o Well, thats substantually different to what others and my limited google serching have been telling me.

Nick_A

Maybe most do but get the right one and don't look back!