I apologize for the way this may be laid out, I'm putting my thoughts down the best I can (I'm a bit scatter brained at the moment). Assume everything is a question

So Assuming I'm using a Linux OS for the base, dual controller SAS setup What different ways do we have to configure the system for a SAM-SD setup?

to make things simple, lets not talk about how to make the cluster, but assume there's four server, each server has 100TB attached to each controller (10 10TB drives, yes I know they don't exist but for easy numbers we'll use it).

Starting from the ground goind up (before clustering). There are a couple options for redundancy. Are all of these feasible? are all of these feasible for HA?

• JBOD on each controller, md for software RAID 0 (200TB Total Storage)
• JBOD on each controller, md for software RAID 1 between controllers (100TB Total Storage)
• Raid 5/6 on each controller, md for software RAID 0 between controllers (160-180TB Total Storage)
• Raid 5/6 on each controller, md for software RAID 1 between controllers (80-90TB Total Storage)
• RAID 1 Array on each controller, md for software RAID 0 between controllers (100TB Total Storage)
• RAID 1 Array on each controller, md for software RAID 1 between controllers (100TB Total Storage)

I think this would related to the number of SANs you have, for example, if you have 4 SANS in the cluster, JBOD with RAID 0 might be fine for you???

I feel like RAID 5/6 might be pointless? Sure you can support 1 to 2 failed drives in each hardware array, but considering you are supporting multiple software arrays this might just be extra overhead with no real benefit? or maybe the rebuild time on a big RAID 5/6 array is worth having this fail safe in place?

Hardware RAID 1, with software RAID 1, in a cluster, seems super over redundant, or maybe not if the data is that important to you (which I can see it being that important).

Also is the cluster for redundancy? or higher storage amounts? or some kind of both? (Can you do that?)

Maybe a question should be what is the normal setup for a dual controller SAN?

Any input is welcome!

Excellent logic! Pinky up

Interesting, I bet not auto-generating KMS keys will stop no one from pirating their software, just makes your life slightly more difficult

so why do they make boxes with dual controllers in them then ? I'm referring to your favorite, Nexsan @scottalanmiller

Hello!

Thank you for all the information so far and I hope I'm not sucking you dry for information (I've read all the links you've posted already).

so can't DRBD use FC for the replication? or does it have to use LAN? and if we're forced to do Lan, we should be able to trunk some ports together to get higher throughput no?

Thank you for all the information so far and I hope I'm not sucking you dry for information (I've read all the links you've posted already).

so can't DRBD use FC for the replication? or does it have to use LAN? and if we're forced to do Lan, we should be able to trunk some ports together to get higher throughput no?

So really the only correct solution is a RAID 10 setup with mirroring over FC or iSCSI? I still feel like you'd be stuck with a whole lot of rebuild time if a drive failed in one of the arrays, although the rebuild time should be faster as long as you don't have a failure in both JBOD arrays on a single server?

so for a large setup like that (50 drives), would you want to do a raid 6 per 10 drives and software raid 0 them together to allow for a quicker rebuild time with more drives being able to fail simultaneously?

I wasn't sure how far you would really need to take for mission critical data. I was assuming that at some point you only want the data mirrored once. Whether that was mirrored at the drive level or at the system level I wasn't sure. I'm assuming if you have huge storage arrays you'd want to have two SANs with JBOD Arrays, mirrored across each other? or would you want to have a RAID6 setup in each SAN and then each SAN mirrored to each other? this way (like we talked about earlier) you can have a few drives go bad and not have to rebuild the entire array. In my mind the second way (with RAID 6) seems to make the most sense?

so why do they make boxes with dual controllers in them then ? I'm referring to your favorite, Nexsan @scottalanmiller

@Dashrender said:

@scottalanmiller said:

In your OP you said dual SAS controllers, that is how this is handled for high end enterprise servers $50K and up. The high end doesn't use RAID controllers at all, only SAS. SAS controller with software RAID can do the redundancy that can't be done with what is on the market for RAID controllers well.

So with the OP, would the question be more like, which RAID level should I use over all theses drives in software, vs one controller RAIDed against the other controller?

And would a SAM-SD really look at skipping hardware RAID for software?

That may have been more of what I was looking for but didn't know how to ask the question

I did skim that but wasn't sure where the risk vs. reward scale crossed in regards to RAID

I assumed SAS has built in raid which I realize now was a bad assumtion. dual controllers would just be used to increase the number of drives you could stick in a box then which makes more sense.

so really a HA SAN for an enterprise wouldn't really be more than 2 ish SANs? And more than that you would go for more of a RAIN setup?

I figured duplication over a network even with 40GB pipes would still be painful but wasn't sure

@scottalanmiller said:

@GotiTServicesInc said:

In my research I may have confused dual channel raid controllers with dual controllers.

Definitely different things. One is more or less just for SAS level channel throughput. The other is for redundancy at the controller level (in theory.)

Yeah I think I just had a brain fart when going over that, I understand the differences between it but got lost in the sauce swimming between the two topics heh