cache

[mbhmirc]

Hi,

I'm looking to buy this series of sans vs some other providers. How is the cache done on this, the other unit's we have looked at have SSD and on-card cache? I can't seem to see this on the spec's in this unit as it looks like it uses normal ram, on board bbuc and nothing else?

I assume you can allocate the above two cache's on this unit per lun?

[Johan Guldmyr]

If anybody knows better please say so,

but as far as I know the P4000 has hp smartarray cards inside them and a BBWC.
With smartarray cards you set the cache ratio (read/write) on the whole controller, not per LUN.

[mbhmirc]

So your limited to the onboard cache? Or can you expand it?

Just on some other SANs you can add ssd cache etc on top of the on-card cache. Has anyone got some documentation on this as I need to know re a database application for a potential client if this is capable of some high traffic writes.

[virtualmatrix]

Maybe not what you're looking for, but with the VM version of the P4000 (VSA), you could get creative and put whatever physical storage solution you wanted into each box as long as the hypervisor supported it. To your question, some RAID controllers support leveraging a few attached SSDs as a another cache tier.

Yes, there is a bit of penalty for the virtualization, but if you have a specific application in mind, by optimizing the storage, you may negate that penalty when compared to the off-the-shelf hardware P4000. Lots of variables to consider.

To the forum at large: :-)
Has anyone put together an SSD or hybrid SSD+SAS/SATA SAN using the VSA?

[Jitun]

On P4000s you have the 512Mb memory of the RAID Controller as well as most part of the system RAM for IOs as well, which is approximately 4 Gb.