topic Re: Which Switch for my iSCSI SAN in HPE EVA Storage

Which Switch for my iSCSI SAN

Dooley do — Thu, 16 Oct 2008 10:23:16 GMT

Hi, I am deploying a small iSCSI SAN with 2 x MSA2012i.

They are dual controller models so I am going to create a dedicated LAN for the SAN using 2 switches for redundancy. There will be 4 servers attached to the SAN whish wil host our file shares and d2d backups.

I want to maximise the speed this will operate and have read about using Jumbo Frames and Flow control. A variety of ProCurve switches support this but it seems my preffered switch, the 2810, does not supoprt both at once.

Anyone got any recommendations for th best switch for this setup? The 1800 series look as though they will do the job but will they create a bottleneck?

Thanks

Re: Which Switch for my iSCSI SAN

Uwe Zessin — Thu, 16 Oct 2008 10:43:10 GMT

I have been told by somebody who talked to HP that the 1800 series is not suited for this type of environment, because their internal memory is quite limited.

On a different project, I had a test setup with an MSA2012i, two ProCurve 2824 (J4903A), two ProLiant DL380 G5 running VMware ESX V3.5. From inside a virtual machine and through the iSCSI initiator I was able to read a little over 100 MBytes/sec using pure sequential 16KB packets on a 4-member RAID-5 volume (64KB chunk size). Didn't do any tuning.

Re: Which Switch for my iSCSI SAN

Dooley do — Thu, 16 Oct 2008 12:09:26 GMT

Are the 2824 and 2810-24G comparable products? I no longer see the 2824 on the UK ProCurve website>

Re: Which Switch for my iSCSI SAN

Ralf Krause — Fri, 17 Oct 2008 05:31:26 GMT

You are right, the 2824 is not available any longer.

Unfortunately (marketing-wise), we have a 2810, which - based on the naming - seems to be the successor of the 2800 series.

In fact, the real successor is the 2900 series!
The 2810 is limited (compared to the 2800 and 2900 series) with regards to:
- feature set (but it does support flow
control as well as Jumbo frames!)
- Port buffers
--> And that's the main reason I would
not suggest this box in an environment
where performance is key (e.g. with
iSCSI).

Conclusion: I would go for the 2900 series.

Re: Which Switch for my iSCSI SAN

Igor Ybema — Fri, 17 Oct 2008 06:09:46 GMT

The 2900 is indeed the minimum what you need for good iscsi performance. However in my 4 year experience with iscsi and switches for iscsi I would recommend you to look into the 3500/5400 series which do much better in buffering even more (however, you get PoE for free, which you don't need...).

But I even would recommend you to look further in other brands like Cisco 2970, Nortel 5510 or Foundry FESX424.
The added value for the cisco and the nortel is that they allow you to stack two switches which will allow you to use trunking to both switches from your servers.

Re: Which Switch for my iSCSI SAN

Dooley do — Fri, 17 Oct 2008 07:35:08 GMT

Hi,

Thank you for both responses. I am on a bit of a budget here so shall research the models suggested. At one site I have about 1.5TB of data and associated backup which will go through the SAN. Mostly file shares/profiles etc and not Exchange/SQL (apart from backup). I think I can afford to go for the 2900s here.

At the other site it is purely about 600Gb of file share which will also be backed up over the SAN. There are around 40 users so nothing too heavy. Might have to go with the lower spec here.

So does the 2810 support both Jumbo Frames and Flow control at the same time as I have read elsewhere that it does not.

Cheers

Re: Which Switch for my iSCSI SAN

Igor Ybema — Sat, 18 Oct 2008 06:10:12 GMT

I haven't used the 2810 before in iscsi so don't know if jumbo and flow control at the same time is supported. However if the 2810 is indeed the same as the 2900 with lesser specs I would guess that it is supported.
However due to the lack of large port-buffers you could run into problems. However, in your setup I think you can do with the 2810 if your budget does not allow the 2900. Because you are not doing really critical traffic over the switches so you can allow some drop in performance.

Remember, the choice for the switch is only about who is the weakest link for performance in your setup. If you buy a high speed iscsi device (like equallogic) you will need a high performance switch also.

Re: Which Switch for my iSCSI SAN

Bart_Rajchel — Fri, 06 Feb 2009 17:59:13 GMT

Hi,
I would like to know if you had a chance to sort this out. We actually have the 2810 for our production network as well as our iSCSI network. I have to say that the performance is extreamly slow. We have over 2 TB of data on MSA2012i and our backups take more then 31 hours using HP LTO4 MLS4048. What we found out that we are not supplying the tape drive with enough data to keep the drive busy. After few tests we realized that our iSCSI speed is at most 15-20MB/s. I would like to know if you are using the 2810 switches and what is your tranfer rate on files. For the test we are using a 5GB file to see some consistent results over longer period of time.
Thanks
Bart

Re: Which Switch for my iSCSI SAN

Evert Goor — Mon, 09 Feb 2009 13:51:16 GMT

Best is to use switches from the 29XX series and higher. We have multiple problems with 28xx series with high bandwith applications.
Mostly it happens when ther are multiple streams going to one device connected on that switch. Single streams are mostly ok.