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Possible to add RAM or Additional NICs to HP Lefthand P4500

crucialx
Advisor

Possible to add RAM or Additional NICs to HP Lefthand P4500

Is it possible to add more RAM or 1Gbit NICs to the HP LeftHand P4500s?

Does adding more RAM give more performance?

Does adding more Gbit NICs allow you to configure them through SAN/IQ?

I'm aware of the 10Gbit option, however looking at options to increase the number of Gbit ports.
9 REPLIES
Patrick Terlisten
Honored Contributor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Hello,

sure it will work, if you add more RAM to the box, but I think it's no supported. Same for additional NICs. Only way to get more performance, if your network is the bottleneck, is to add the 10 GbE upgrade kits.

Regards,
Patrick
Best regards,
Patrick
crucialx
Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Hi Patrick,

So by adding more RAM you will not get any additional performance?

Also, by adding additional 1Gb NICs, you will not be able to use them?

Regards,
Aaron
Patrick Terlisten
Honored Contributor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Hello Aaron,

yes, that's my opinion. It may work, but it's unsupported.

Regards,
Patrick
Best regards,
Patrick
kghammond
Frequent Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Also, from my deep dive conversations with multiple layers within HP/Lefthand, my understanding is that the majority or all of the caching is done via the RAID controller cache as that is the only BBU cache availble to a LeftHand node. It is possible that it uses RAM for read caching, but I neither got that impression or confirmation from Lefthand engineers.

Please correct this statement if it is incorrect.

If this statement is correct, then adding RAM will have negligible impact on performance.

The same goes for additional NIC's. You really need to read the iSCSI deep dive documentation at various locations on the net. A single 1 Gbe NIC will max out around 125 MB/sec depending on the TCP/IP overhead. Without MPIO adding more NIC's will not help on a per individual LUN basis. Each LUN will have a max of 125 MB/sec regardless of the number of nics and regardless of the disks in the unit.

With MPIO round robin, two nics should be capable of carrying 250 MB/sec of disk traffic. Since all LeftHand data is written randomly (not sequentially), I am not sure if 8 or 12 drives can fill a full 250 MB/sec. I suspect there are only some rare circumstances where you could fill two 1 Gbe pipes with purely random disk activity.

It would seem to me the biggest benefit of the 10 Gbe upgrade option is to increase the per LUN (session) limitation of 125 MB/sec for non-MPIO workloads.

Once again, if any of this is incorrect please post the correct information.

I hope that helps,
Kevin
ajamil786
Frequent Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

You can monitor memory and network usage via the performance monitor in CMC. If your numbers are below 90%(in my opinion), adding memory or NIC will not help. In my experience memory and NIC have not been the limiting factor. As most storage systems disk is the limiting factor.
Steven Clementi
Honored Contributor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Which is why you typically add more disk(s) to increase performance....

;o)
Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
RHCE
NPP3 (Nutanix Platform Professional)
crucialx
Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

FYI, we have not yet purchased a P4500, we are however looking into doing so and wanted to plan for any need to upgrade to 10Gbe down the track and budget it in as required. I was just checking the available options in terms of not upgrading to 10Gbe if we needed additional throughput.

In terms of going over 1Gbe per LUN, would using bonding of 2 NICs increase throughout to 250MB/s, or would we need to use MPIO? In our case MPIO is probably not an option. We would be looking at using stacking with the NIC bonding to esure no single point of failure.

Regards,
Aaron
kghammond
Frequent Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Keep in mind, the 1 Gbe per LUN is not really a Lefthand limitation, it is an non-MPIO iSCSI limitation. Even with bonded nic's, one TCP/IP session will stick to one LAN interface. Since most if not all non-MPIO iSCSI implementations do not create multiple TCP/IP sessions per LUN, then you cannot exceed the smallest pipe in a single LUN session.

Even if you have 10 Gbe on the Lefthand, if your server is only using 1 GB Nic's and non-MPIO, then you will still be limited to a 1 Gbe connection.

This is only per LUN! It should be obvious but for completeness sake, multiple LUN's will create multiple sessions which will naturally load balance across both nic's using a bond.

Another important consideration, if you are using 10 Gbe on your server and 10 Gbe on the Lefthand, but you have trunked 1 Gbe connections between switches. Assuming your LeftHand might be on different switching infrastructure, then you will still be limited to the 1 Gbe of the trunk for an individual LUN (session).

I hope that is pretty clear.

Kevin
crucialx
Advisor

Re: Possible to add RAM or Additional NICs to HP Lefthand P4500

Hi Kevin,

Yes thanks, that definitely helps.

Have a few more questions regarding it still, in the HP documentation it has several different methods of LB connections: http://h10032.www1.hp.com/ctg/Manual/c01750150.pdf

* Link Aggregation - 802.3ad
* Adaptive Load Balancing (Recommended)

With either of these options, is it not possible to reach 2Gbit/s on a single LUN? I was under the improession with link aggregation it is possible to balance traffic based on MAC address (when doing it on a switch), however not sure how HP does it.

On our front end nodes we would probably be doing a similar thing, 2Gbit/s link aggregation.