Some questions from a new owner of SM SC846 & SC847 Chassis

[cgtechuk]

Hi All,

I recently snapped up a bargain here in the UK and managed to get a 24 bay SC846 and a 36 bay SC847 JBOD both with SAS2 Backplanes with expander chips for £400 / $460 which I thought was a great deal .

I have a few questions though as I am new to backplanes and expanders.

There was a motherboard with the SC846 but I didn't get it included to save costs. It came with a SI 9280 Megaraid 4i4e card which I will swap out for a 9201 or 9211 card to get HBA IT Mode

Config wise the SC846 has 1 x 8087 cable which connects to backplane bpn-sas2-846el1
and the SC847 has the CB1 JBOD Power board rather than a MB and has 2 x 8088 connectors on the back which go to backplane bpn-sas2-846el2 as 8087 connectors then from there 2 come out the expander and connect to the rear 12 bay drive backplane. The 8088 connector obviously connects to the SC846 chassis on the ex port.

So if you are still with me this far, I thank you!.

What I am aiming to do is to put a Supermicro X10-SAO in the SC846 chassis and connect as JBOD to the SC847 however here is where I have issues. My drives..

I have a pile of
SAS2 Running at 6GB/s Hard Drives
SATA3 Running at 6GB/s
SATA2 Running at 3GB/s

My plan is to have each of the drive types together so for example a raidz2 with all the SATA3 drives and another raidz2 with all the SAS2 drives in it etc to gain the best overall performance by matching the drives together but my worry is that if I have SATA2 drives on the same Backplane as SATA 3 drives that the whole lot will slow down to SATA 2 speeds is this correct or can they ports run at different speeds depending on what is attached to it? I know that mixing Sata and SAS isnt really an issue anymore on the SAS2 backplane which these come with but I am not sure about the SATA2/SATA3 living independantly.

If they cant live independantly can I isolate them to one backplane e.g have them all on the 12 bay expander on the back of the SC847 or because all the backplanes are linked it will drop to 3GB regardless?

My other thought is that if it came to it due to me having a lot of the SATA2 drives I could just put the backplane that they are connected to on an independant HBA but I would prefer to have everything on the one if that makes sense?


One other quest I am on at the moment is to quieten the thing now, I see a lot of posts on here about many different tricks and that the preferred option is CB3 JBOD Controller and turn the fans down but as I live in UK where it is maybe 25 degrees 2 days a year I am wondering if I can just put a decent fan controller in the JBOD case and hook the fans up to that and keep an eye on drive temps? Is there a preferred PWM Controller? I am guessing if I wanted decent control of the fans I would use a fan controller rather than plug them into the backplane as they never seem to spin down slow enough? They are all PWM Fans but obviously the JBOD Controller only supports 3 pin.

I promise you the post was not meant to be this long but I really appreciate all your help guys!

Some pics here: SC846 / SC847

 

[Rand__]

Nice deal
How many drives of which type do you have?
What OS are you planning on?

Re the detail question I have no first hand knowledge but I'd assume they should sync up independently (at least at channel level). Depending on drive count you might want to use a SAS3 HBA (bandwith aggregation).
Else it you might want to split up backplanes to get failure domains and handle independent drive speeds (eg 12 847 rear drives at 1 channel can be faster individually then the 24 in front). Also thermal restraints apply on the rear drives.

Cooling - Fan choice is one option, Fan controller the next. No idea what is up to date but you need a bunch of channels and a way to mount it outside the case... so many of the PC based ones are out...

 

[i386]

if I have SATA2 drives on the same Backplane as SATA 3 drives that the whole lot will slow down to SATA 2 speeds is this correct

Expanders are like switches, each port runns at the fastest speed supported on both ends. Sata2 should not slow down the whole expander.

I know that mixing Sata and SAS isnt really an issue anymore on the SAS2 backplane

Be carefull with that! Don't mix sas and sata drives in the same logical volume as sata and sas have different timeouts, error handling and a few more things.

One other quest I am on at the moment is to quieten the thing now, I see a lot of posts on here about many different tricks and that the preferred option is CB3 JBOD Controller and turn the fans down but as I live in UK where it is maybe 25 degrees 2 days a year I am wondering if I can just put a decent fan controller in the JBOD case and hook the fans up to that and keep an eye on drive temps? Is there a preferred PWM Controller? I am guessing if I wanted decent control of the fans I would use a fan controller rather than plug them into the backplane as they never seem to spin down slow enough? They are all PWM Fans but obviously the JBOD Controller only supports 3 pin.

I would not put a pwm controller in an enterprise chassis like the 846 and especially not in the 847 with 36 bays. The controller will run the fans as slows as possible which could be dangerous for the hdds, add-on cards, onbaord chipset/hba/raid controller.

 

[cgtechuk]

Nice deal
How many drives of which type do you have?
What OS are you planning on?

Re the detail question I have no first hand knowledge but I'd assume they should sync up independently (at least at channel level). Depending on drive count you might want to use a SAS3 HBA (bandwith aggregation).
Else it you might want to split up backplanes to get failure domains and handle independent drive speeds (eg 12 847 rear drives at 1 channel can be faster individually then the 24 in front). Also thermal restraints apply on the rear drives.

Cooling - Fan choice is one option, Fan controller the next. No idea what is up to date but you need a bunch of channels and a way to mount it outside the case... so many of the PC based ones are out...

Hi, Thanks for your reply, I plan on installing ESXi first of all and have a FreeNAS VM with the HBA passed through to allow ZFS full access to the disks. Reason why I virtualise is that is easier to snapshot the VM, Backup Config, Rollback etc, also means I can use it as a VCenter VM and also a Domain controller as it will be always on

I have about 20 SATA 2 Drives that are being slowly replaced with Sata 3 drives as and when I get them (Money) 12 WD SAS Drives and the rest SATA3

I was hoping someone knew definifitvely the answer about the speeds though before I start building it up but SAS3 is out of my price range at the moment

 

[cgtechuk]

Expanders are like switches, each port runns at the fastest speed supported on both ends. Sata2 should not slow down the whole expander.

This is what I was wondering but I was wondering if at backplane level it would slow it down for example if I have 4 sticks of DDR3 RAM and 3 are 1600Mhz and one is 1333MHz the whole lot runs at 1333Mhz which is why I ask

Be carefull with that! Don't mix sas and sata drives in the same logical volume as sata and sas have different timeouts, error handling and a few more things.

Im not sure I was probably clear enough in my first post what I meant by this is that I would group the disks together by type so say 12 x SAS and 12 x SATA i would create two seperate logical volumes not one big one if that makes sense

I would not put a pwm controller in an enterprise chassis like the 846 and especially not in the 847 with 36 bays. The controller will run the fans as slows as possible which could be dangerous for the hdds, add-on cards, onbaord chipset/hba/raid controller.

A few others from search results have used PWM Controllers without any real ill effect including someone with a SC847 they used a Zalman PWM Mate I beleive, Trying to explore options at the moment and trying to work out if Backplane or Motherboard Fan connection is best