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SAS backplanes

C

ChemicalSmile

n00b
Joined
Nov 23, 2011
Messages
37
Hello all,

I'm new to the forum but hope to be sticking around. Seems like an excellent source of technical information with an active community.

I'm in the early stages of designing an SAS storage enclosure and am having a hard time locating SAS back-planes. Seems hard to find vendors who have Chenbro or Supermicro back-planes in stock and available for sale. Anyway, I'm not concerned with the brand yet. The only specifics I have in mind at the moment should be fairly trivial. I'd like the back-planes to be powered with either single or dual 4-pin molex connectors. For port count, 4 or 8 port would be good but I'll look at anything. I'm planning to mount the back-planes on standoffs and load the drives vertically (like one of SUN's Thumpers). If anyone has any information on where I can purchase SAS hardware of this type online I'd be grateful.

Thanks to all who took the time to read.
 
Nice. I am also trying to do something very similar. I bought a Dell 8 x 3.5" SAS backplane (KU482) from ebay for $20 shipped. However it uses a funky 22-pin power connector and I do not know its pinout. http://hardforum.com/showthread.php?t=1651747

As soon as I get the power connector's pinout, I am planning to mount the SAS backplane to a blank metal plate with standoffs, and build a cage like structure around vertically inserted drives (sort of like backblaze pod). I would then mount the metal plate inside of my RSV-L4000 enclosure via velcro (after removing stock drive bays/cage).

Can anyone help me out with the pinout? It's from a Dell PowerEdge 2900.
 
JinNjuicE said:
Nice. I am also trying to do something very similar. I bought a Dell 8 x 3.5" SAS backplane (KU482) from ebay for $20 shipped. However it uses a funky 22-pin power connector and I do not know its pinout. http://hardforum.com/showthread.php?t=1651747

As soon as I get the power connector's pinout, I am planning to mount the SAS backplane to a blank metal plate with standoffs, and build a cage like structure around vertically inserted drives (sort of like backblaze pod). I would then mount the metal plate inside of my RSV-L4000 enclosure via velcro (after removing stock drive bays/cage).

Can anyone help me out with the pinout? It's from a Dell PowerEdge 2900.
Click to expand...

Sounds similar to my plan. I've built backblaze pods. SATA port multipliers are fairly cheap and easily had. Seems different with SAS back-planes. Your comment on the Dell's proprietary power connector is why I'm trying to source for back-planes that use standard molex connectors. Fabbing up a custom harness if I had the correct pinouts is doable but I'd rather skip that step since I'm planning this from scratch. A usable back-plane is the first building block in my particular case.
 
Stanza33 said:
Search Ebay for old HP Server Backplanes

Eg ML350 G5 ( 8 x 2.5inch or 6 x 3.5inch) for example.

They can be had cheap... you just need to work out the power plug pin out (info can be found)

Hell you can even if you are lucky find ML570 G3 or G4 18 x 2.5inch drive backplanes out of HP's for cheap there.

some examples for you

http://forums.overclockers.com.au/showthread.php?t=962776

http://forums.overclockers.com.au/showthread.php?t=962861

Search Ebay for

HP SAS Backplane....;)

.
Click to expand...

Thanks for the info Stanza33. I was thinking about going the e-bay route. My biggest concern is eventually being able to have reliable access to a source of new back-planes so I can standardize my design for large scale production. Right now metal fabrication is not an issue. I've ordered a variety of raid controllers and SAS expanders to bench test. The chassis will be fully custom and the majority of the hardware I need is commodity and readily available from many vendors. Just the damn back-planes that are the sticking point. I'm new to SAS in general, but would fanout cables be a possible alternative to the back-planes if I could mount them suitably? I'd be losing at least the enclosure management features of the back-planes, but what other losses would I see? Any and all idea's are welcome. Thanks again.
 
Stanza33 said:
Build your own??

Amphenol connectors

http://forums.overclockers.com.au/showpost.php?p=13327990&postcount=1472

No smarts tho

.
Click to expand...

Thanks once again. You have me thinking. I'm going to dig around for info on available connectors. If I can find wiring harness's / connectors like those, fabricating my own simple back-planes (albeit without the brains) should be possible. I can have a similar metal bracket to the one you showed in your link cut on the water jet easily enough and I can modify it to suit my needs.
 
I was looking at single disk back-planes like the one at
http://www.budgetgadgets.com/serial....html?osCsid=399434781b3488a94dc46ccc18c75211 and had a few questions. The connections for signal1 and signal2 are confusing me. Would I be able to attach 4 of these to a standard fanout cable, using just the signal1 connector on each board, or do I need to connect both signal1 and signal2? I can't tell from the picture but it looks like the signal connectors may be 7-pin sata connectors. If I can cable one up will I get true SAS performance out of it? Any input would be appreciated. If you know of a specific fanout that will run from the mini-sas on my expander and mate to the signal connector on the board that would be great as well.
 
@ChemicalSmile:

You only need to wire out the Signal1 connector if you intend on using SATA drives. The Signal2 connector is for SAS drives and is used for redundant connections.
What do you mean with 'true SAS performance'?
If by mini-SAS you mean a SFF-8087 connector, then you will need a SFF-8087 to SATA breakout cable to use these backplanes.
 
The connections for signal1 and signal2 are confusing me.
Click to expand...

SAS drives support redundant raid cards that can be used to prevent a raid card from death from taking down the system.
 
treadstone said:
@ChemicalSmile:

You only need to wire out the Signal1 connector if you intend on using SATA drives. The Signal2 connector is for SAS drives and is used for redundant connections.
What do you mean with 'true SAS performance'?
If by mini-SAS you mean a SFF-8087 connector, then you will need a SFF-8087 to SATA breakout cable to use these backplanes.
Click to expand...

Sorry if I'm not making myself clear. SAS is new to me. I've only worked with SATA. The expander I'm looking at uses SFF-8087 connectors on the card. I understand that I can fan each port on the expander out to 4 drives. I'd like the ability use either SAS or SATA in the setup. I envisioned running a fanout cable to just 1 of the signal ports on 4 of the mini back-planes I linked to. I understand signal1 and signal2 paired together to be redundancy in a high availability setup. Please correct me if I'm wrong. I hope that explains it a bit better. By true SAS performance I was wondering if it would perform, with only one signal hooked up, equivalently to a full featured SAS back-plane, like a Chenbro that does 12 drives for instance minus the management features of course.

So, are the two hookups required for SAS use or will it work fine with one but lack redundancy? On a related note, do all commercial SAS enclosures come with this same dual signal redundancy implemented or is it dependent on the model purchased / clients needs? Thanks for the answer and sorry for the long winded response. Trying to be clear while wading into new territory.
 
Yup correct, SOME SAS Drives are Dual Ported

ie two wwn addresses (Think network terms MAC Address) on the same HDD - very similar to Fibre Channel. SAS talks directly to a wwn.... not like SATA which is poinjt to point SERIAL communication.

So for bigger SERVER based configs to factor in some redundancy... you would say have

Dual ported SAS drives
Connected to a Dual ported Backplane
Connected to dual SAS controllers

if for simplicty sake the SAS drive had say 2 x wwn names of "wwn.ABC" and "wwn.123"

in effect with the two controllers

Controller A could be talking to wwn.ABC
Controller B could be talking to wwn.123

If controller A dies.... you can still reach the HDD thru Controller B's path to wwn.123;)

Similar to having 2 x Network cards connected thru 2 x switches or 2 x fibre channel cards and 2 x fibre channel switches etc

for home use totally over the top... but for critical business operations... well worth it.

In your case if you are using SATA.... totally pointless;)

.
 
Stanza33 said:
Yup correct, SOME SAS Drives are Dual Ported

ie two wwn addresses (Think network terms MAC Address) on the same HDD - very similar to Fibre Channel. SAS talks directly to a wwn.... not like SATA which is poinjt to point SERIAL communication.

So for bigger SERVER based configs to factor in some redundancy... you would say have

Dual ported SAS drives
Connected to a Dual ported Backplane
Connected to dual SAS controllers

if for simplicty sake the SAS drive had say 2 x wwn names of "wwn.ABC" and "wwn.123"

in effect with the two controllers

Controller A could be talking to wwn.ABC
Controller B could be talking to wwn.123

If controller A dies.... you can still reach the HDD thru Controller B's path to wwn.123;)

Similar to having 2 x Network cards connected thru 2 x switches or 2 x fibre channel cards and 2 x fibre channel switches etc

for home use totally over the top... but for critical business operations... well worth it.

In your case if you are using SATA.... totally pointless;)

.
Click to expand...

Thank you again for the help. Very good explanation. For the sake of discussion, if a person wanted redundancy in an enclosure, having the data mirrored to multiple enclosures would accomplish the same? Ignoring the downside's to the scenario, a similar level of redundancy would be achieved? Also, while discussing redundancy, redundant power, redundant boot drive, mirroring the data across multiple enclosures, etc. What other redundancies would be desirable? I know backblaze style enclosures, besides being SATA, lack redundancies. In their special use case this works for their company but is obviously not ideal. I've done a backblaze style unit with mirrored boot drives and redundant PSU's and am planning on having a minimum of the same in my SAS setup. Anyway, thanks again for all the help. I've ordered in a few of those mini back-planes to experiment with. I'd be happy to let you all know how the build progresses and evolves.
 
You can take it as far as your wallet will allow.

When you are talking serious hardware that cannot fail.... then you start getting into enterprise gear

things such as

Redundant CPU's
Redundant or RAID'd Memory Modules
Clustered Servers
Hot swap just about every important component etc.
Big dollars

Hell some big companies even have Hot Swap Servers.... ie a whole other identicle server sitting beside the working one in case it fails.

When you are talking downtime in the millions of dollars an hour... having $80,000 of spare server sitting there doing nothing ..... "just in case" is a small price to pay.

Tho it's less likely these days with virtual server etc. Tho it still happens for systems that can't be virtualised easily.

Backblazes redundancy is in their software (as apposed to hardware)...
When you have the same DATA spread across multiple storage pods...you have no need of redundancy in the actual storage pods.

.
 
Stanza33 said:
You can take it as far as your wallet will allow.

When you are talking serious hardware that cannot fail.... then you start getting into enterprise gear

things such as

Redundant CPU's
Redundant or RAID'd Memory Modules
Clustered Servers
Hot swap just about every important component etc.
Big dollars

Hell some big companies even have Hot Swap Servers.... ie a whole other identicle server sitting beside the working one in case it fails.

When you are talking downtime in the millions of dollars an hour... having $80,000 of spare server sitting there doing nothing ..... "just in case" is a small price to pay.

Tho it's less likely these days with virtual server etc. Tho it still happens for systems that can't be virtualised easily.

Backblazes redundancy is in their software (as apposed to hardware)...
When you have the same DATA spread across multiple storage pods...you have no need of redundancy in the actual storage pods.

.
Click to expand...

Exactly my thinking. Right on about backblazes software solution as well. Thanks again for the help. I'll keep this thread updated, more so once my hardware begins to arrive.
 
Hello again,

My employer informed me that the enclosure I'm working on requires four external ports,each to host. Anyone have any solutions? I haven’t seen anything that has 4 external ports meant to link to 4 individual hosts. Any ideas would be appreciated. Can a single external to host port be fanned out to 4 hosts? Also, are there any SAS expanders out there with enough ports to support 48 drives or is there a way to bridge two cards that support 24 apiece and have them behave as one expander?

Thanks in advance
 
Last edited:
I don't think there are any single expanders with enough ports to offer 4 paths to 48 drives, but you may be able to use multiple expanders. As in, use 2 28-port expanders to connect to drives, and a 3rd 28-port expander to aggregate the drive-connected expanders while connecting to 4 host controllers.

You could also possibly use 4 28-port expanders to multipath the drives, and 2 28-port expanders to aggregate the drive-connected expanders. The 2 aggregating expanders would be connected to 4 host controllers and 2 drive-connected expanders each, providing two paths to all 48 drives for each of 4 hosts connected.

From the product brief on the LSI SAS2x36 chip used in the newer Chenbro expanders, I get the impression that scaled and redundant topologies , or "SAS fabrics", are the design aim. I don't know how far you can take it, though.
 
Tiberizzle said:
I don't think there are any single expanders with enough ports to offer 4 paths to 48 drives, but you may be able to use multiple expanders. As in, use 2 28-port expanders to connect to drives, and a 3rd 28-port expander to aggregate the drive-connected expanders while connecting to 4 host controllers.

You could also possibly use 4 28-port expanders to multipath the drives, and 2 28-port expanders to aggregate the drive-connected expanders. The 2 aggregating expanders would be connected to 4 host controllers and 2 drive-connected expanders each, providing two paths to all 48 drives for each of 4 hosts connected.

From the product brief on the LSI SAS2x36 chip used in the newer Chenbro expanders, I get the impression that scaled and redundant topologies , or "SAS fabrics", are the design aim. I don't know how far you can take it, though.
Click to expand...

Thank you. Maybe I'm over my head on this one. Buying 3 or 4 28 port expanders sounds pricey. At the moment I've got 2 24 port RES2SV240 Intel expanders. I could grab a third or even fourth if I though they'd meet my needs. If I had 4 of these, (I know they're not 28 port) and ignored the multipath option for experimental purposes, how would I go about implementing a setup like you've mentioned? I need the drives to be seen properly by the hosts RAID controllers so that an array can be implemented. I'm a little slow on the uptake but I promise that if you all invest the time to help me out it won't be wasted. I've got hardware now and more on the way. No way am I giving up. Even a link to some informative reading on a setup like this would be great. Also, on a different note, any special hardware you all would like to see manufactured at a decent price? During the process everyone can have their say and banter about the pro's and con's of different setups until we can all arrive at a conclusion. I've got the resources and the end products are open source. Let me know here if you're interested.


Thanks in advance
 
You havn't actually said what you are trying to acheave from this.??

Are you trying to pool 48 drives into One large array then have 4 servers connect to it?

Are you trying to make a backplane to hold 48 drives, then have 4 servers connect to 12 drives each in the backplane?

.
 
Stanza33 said:
You havn't actually said what you are trying to acheave from this.??

Are you trying to pool 48 drives into One large array then have 4 servers connect to it?

Are you trying to make a backplane to hold 48 drives, then have 4 servers connect to 12 drives each in the backplane?

.
Click to expand...

Preferably 48 drives in one large aray with 4 external "to host" ports available if at all possible. Sorry for leaving that tidbit out. Obviously an important one. Thanks for the help. Any adapters out there that offer 4 externals?
 
I think you are barking up the wrong tree and possibly need to read more into how SAS / SATA works.

To achieve the result you are wanting you are either going to have to...

Have a SERVER pool the 48 drives together.
Then share that pool out via NFS / iSCSI / Fibre channel..... You can't however share it back out via SAS/SATA

ie if you say looked at some other peoples configs of NORCO Rack Mount Cases (but in your case you would need 2 of them daisy chained together) 24drives each.

In which case you are going to need your expanders to connect one or two SAS controllers to all the drives. Which you would then either use a RAID card to pool all the drives.....or Software RAID.

Run something like Solaris Express with ZFS to pool the drives together into one.

Then you could share the pool out to 4 other servers either via Ethernet (Multiple 1GB ports / 10Gbe "infiniband" or Fibre Channel)

Depending what the OS's of the connecting Servers will be.... you also have the option of say running Ehternet over SAS....not all OS's support this tho.

So there are ways to get similar to how you plan.

Tho NO you can't ACTUALLY configure it / connect it up how you think.

.
 
Stanza33 said:
I think you are barking up the wrong tree and possibly need to read more into how SAS / SATA works.

To achieve the result you are wanting you are either going to have to...

Have a SERVER pool the 48 drives together.
Then share that pool out via NFS / iSCSI / Fibre channel..... You can't however share it back out via SAS/SATA

ie if you say looked at some other peoples configs of NORCO Rack Mount Cases (but in your case you would need 2 of them daisy chained together) 24drives each.

In which case you are going to need your expanders to connect one or two SAS controllers to all the drives. Which you would then either use a RAID card to pool all the drives.....or Software RAID.

Run something like Solaris Express with ZFS to pool the drives together into one.

Then you could share the pool out to 4 other servers either via Ethernet (Multiple 1GB ports / 10Gbe "infiniband" or Fibre Channel)

Depending what the OS's of the connecting Servers will be.... you also have the option of say running Ehternet over SAS....not all OS's support this tho.

So there are ways to get similar to how you plan.

Tho NO you can't ACTUALLY configure it / connect it up how you think.

.
Click to expand...

Not surprising I'm barking up the wrong tree. How many drives can I work with and still have output to 4 hosts? The output to 4 hosts seems to be the clients sticking point. Also, someone mentioned using two ex panders along with a third to aggregate the drive pool. Any info or suggestions there? he output to 4 hosts apparently is a must according to what I've been told.
 
Am I correct in guessing the 4 x servers connecting to it are Virtual Servers?
ie ESXi or Xenserver etc?
 
Stanza33 said:
Am I correct in guessing the 4 x servers connecting to it are Virtual Servers?
ie ESXi or Xenserver etc?
Click to expand...

Unfortunatley I'm not thinking this is the case. My employer relayed the message from the client to me. Client wants 4 physical external "to host" ports on this thing. If it's undoable, then they'll have to go another route. Believe me I wish I had more info. It's my companies policy to tell me as little as possible and then set me loose while expecting miracles. Go figure. Thanks again for all the help Stanza33. I hate to chew up all your time on a project that is quite possibly impossible.
 
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