EVA 8400 Processor Speed

[BrianPB]

Anyone know the Processor Speed of the 8400's controllers? Have they gone to 64bit? Or is it still 32bit?

[Steven Clementi]

Why would this even matter? (Just wondering)

[Víctor Cespón]

I don't think that has been published anywhere public, but anyway it's irrelevant, the controller CPU has never been limiting the performance on an EVA.

Moving to 4 or 8 GB of cache per controller, and to SSD drives gives a much bigger performance improvement.

[BrianPB]

Not thinking about performance per se, but it seems like scalability is lacking slightly in the 8400. Was hoping for something more. Wondering if processor speed limits the amount of drives the back end can handle.

[Víctor Cespón]

Can't follow your logic. The CPU on an EVA8000, even fully loaded with 18 enclosures seldom goes above 20%.

The 8400 has 20% more performance, 3 independent loop pairs with 9 enclosures, 108 drives per loop.

The limit for I/O are always the disk drives. Assumming a typical 8K I/O size, and a maximum 150 I/Os per drive (15K drives), that's 1.2 MB/s per drive or 130 MB/s per loop. The backend is all 4 Gb/s, so...

[BrianPB]

Right. I guess I'm wondering why they limit the 8400 to 324 Drives. I can understand it with the 8000/8100 with the CAN switches, but you would think now that they have gone to the cascading disk shelves that they would have offered more capacity especially in the 8400. Thought it might have been processor limited, or perhaps just marketing... :)

[Víctor Cespón]

No, that's due to the FC_AL protocol. There are 127 AL_PAs per loop, you need 108 for the drives, 9 for the I/O modules and 2 for the controllers.

Not enough addresses to have 10 enclosures per loop. Anyway, the I/Os are daisy-chained, a packet has to pass through several I/Os to reach it's destination disk. Not good to have too many.

[Susan Tafolla]

what if the IO is 256K rather than 8K? the max IO per disk could be 256K x 150 ios/second?

[Patrick Terlisten]

Hello,

there is a german saying: "Haette, waere, wenn". You need 108 drives, with each drive delivering 150 IOPS with 256k IOs to fill up a 4 GB backend-loop. Sure you can do this, but that's theory.

Think about EMC² CLARiiONs which are still using Intel P4 CPUs on their storage processor.

The limiting factor are the loops, not the controller. The cache upgrade is more marketing then true need. HP no differs anymore the cache in differnt parts, cache is cache.

Best regards,
Patrick

[Kranti Mahmud]

Hi BrianPB,

Check this PDF: http://hp.sharedvue.net/sharedvue/resources/tsg-fg-storageworks_array.pdf


Rgds-Kranti