Reorg of Controllers and expanders - options

[BestGear]

Guys

I would really appreciate some advice.

I have a host, with three Dell H200 cards, flashed - two internal and one external, with the external enclosures each having HP SAS expanders. The cases are Supermicro and Norco (no moans with backplanes...so far...).

I want to free up a motherboard slot, and have been looking for a cheap 9201-16i to swap the two H200's out for- but none around really other than chinese offerings which I would rather avoid (rightly or wrongly).

So question - would it be sensible to buy a SAS expander for the main case, and run that off one H200 and thus removing the external H200 and one internal H200? (assuming the sas expander has an external port or indeed use a external bracket to get one).

Would one H200 SAS port provide enough bandwidth or can it use both to the expander? (it would have 16 4TB drives on it in two arrays of 8).

All advice most welcome - thanks for your time.


David

 

[Rand__]

The answer is quite simple -it totally depends
I Am doing similar calculations with better odds atm.
A single 6GBs lane is good for about up to 600MB/s, that's 2400 per Port.
IIf you assume 200MB/'s max per Disk you need 1600 per arrray, 2000 at 250MB/s but only 1000 at 125MB/s.

So depending on disk speed,data type,access patterns etc you will need a single or a double port connection for the 16 drives. Only you know; )

 

[BestGear]

Thanks for the reply.

Will I get double to an expander if I use two ports? - but I do question if I really need this at home from the above calculations.

The drives have media on them, with max 4 users streaming but there are 6 spindles with CCTV - which is pretty much constant.

What would be a sensible SAS expander at 6GB speeds? The old 3GB HP expanders (that work with 4tb and above drives) have been great, but would prefer something at 6gb for this duty.


David

 

[Rand__]

Yes, 8 lanes should double the max throughput.
Intel 6GB/s expanders (RES2SV240) are cheaply available every now and then and they can usually run without PCIe slot, or newer HP if you can find them.

 

[BestGear]

Thanks Rand

I guess my other option is to get a 9201-16i or some other similar card, infact if there was a 3gbs 16i card, that would do as long as it supports >2tb drives. Are there any 3gb 16I cards that support >2tb drives?

Talking of these - what about the chinese knocks offs? - I have seen a lot written elsewhere, usually criticising them, and usually by people who have not bought one! I did see one blog where the guy had flashed it, and it wrote without error but would not actually work with any drives!

One of the Chenbro expanders may be an option - but I am sure that has dedicated in/out ports unlike the way that the HP 3Gb expanders let you use any port for any use.

Looks like there are loads of chinese Intel expanders around too for little money!


David

 

[BestGear]

What about, as a cheap option, retain one H200 - and use a HP 3Gb SAS expander - which would let me remove the external H200 too?

Can I use two SAS channels from H200 to the expander and use any of the expander ports for anything else (internal or external)?

Would two channels to the HBA be of benefit?

 

[Rand__]

What I did originally was to get a cheap -16e and use Ext 6G to 4x SAS INT cables. Not pretty but works fine

Edit:
Double lanes is double bandwith, so o/c it helps.
But I am not sure whether you can freely assign Ports on the expander. I know on my 9 port intel that only 6 are for disks, 2 for uplink to raid/hba and one as daisy chain.
Have not tried other uses (like daisy chain on disk port)

 

[vanfawx]

One of the Chenbro expanders may be an option - but I am sure that has dedicated in/out ports unlike the way that the HP 3Gb expanders let you use any port for any use.

I have one of the 36 port Chenbro SAS2 expanders and you can use any port as in/out.

 

[Aestr]

Talking of these - what about the chinese knocks offs? - I have seen a lot written elsewhere, usually criticising them, and usually by people who have not bought one! I did see one blog where the guy had flashed it, and it wrote without error but would not actually work with any drives!

@BestGear the concern with the knock offs is the unknown parts they've swapped in. In some cases the lower quality components are labelled to look legit and in some cases they don't bother. Either way it seems these usually appear work on arrival, but that could change at any moment. Now of course with any electronic part there's a chance it will fail and a lot of the used stuff that we all buy here has no warranty anyways, so the question you have to ask yourself is whether the additional risk is worth the up front savings (up front because if you have to buy a replacement in 6 months it's no longer cheaper).

Now if you get a grey market card that came out of the actual factory you're likely fine, but there's no way to know for sure.

TLDR: If you're okay increasing the risk to your data and your time you can roll the dice.

 

[BestGear]

Hi

I have just had a nightmare of an afternoon reorganising the controllers, having decided to buy a new 9201-16E.

To recap - I had two H200 (IT) with 16 internal disks and a H200 external (IT) with cabinets. The boot drive is off the motherboard, which is Gigabyte x58.

I am stuck with this so any ideas and experience would be very much appreciated!

Step 1

I removed all three H200 and fitted the 9201-16E and a HP 3GB expander card, with a short external cable between them.

On the expander, I initially connect two of the norco backplanes, ie 8 drives, and booted - and all worked as expected.

Step 2

I connected up another two backplanes adding another 8 drives to the expander (16 on the expander at this point). This time I was greeted by a hang at the boot message "verifying DMI pool". I have seen this before, and clearing cmos can help, but if I remove the two cables I just added, it boots fine, and I an not booting from a drive that is on the 9201, so not sure how it is preventing the boot. I have not cleared cmos at this point - have just left the set of 8 drives detached for now.

Do I need to be careful with the ports I choose on the HP expander? I was under the impression that the card acts like a switch and any port can be used for any purpose.

Step 3

With pressures of time against me, I had to get the server back up and running (household nagging at no internet etc as Untangle runs in a VM on this box) I connected another Norco that I use with an HP 3Gb expander with 24 drives in it. This case/expander has been running 100% reliably for the last two years on a H200.

I shutdown the server, connected the storage to the second 9201 external port and booted the server.

This time I was greeted by a SAS Discovery Error for the disks in the cabinet!

So - I have two issues before I ditch the 9201 idea with these HP expanders....any ideas!?!!?! I have had to revert to the three H200 cards for now (and thinking I just blew too much cash on a new 9201!).

As ever, THANK YOU for your time!


David