How to interpret this output from MegaCli?

Question

/opt/MegaCli -CfgDsply -a0 | less RAID Level : Primary-1, Secondary-3, RAID Level Qualifier-0

Almost positive this is not running a RAID3, my guess is a RAID 10, where "Primary" means what is being done in the "spans" (span being Mega Cli term for the first RAID operation blocks) and then the "RAID Level Qualifier" is the RAID level operation being done on top of the spans, and finally, "Secondary-3" means that there are 3 spans being RAID0'd across. This interpretation matches the disk space sanity checks, indeed the total capacity of the array is that of three physical drives. However, this interpretation and output syntax is convoluted to the point where a clarification is definitely needed.

Solution 1

Your answer appears to start at page 13 of this SNIA specification http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf

Primary-1 "Mirrored array"

Secondary-3 "Spanned 0x03 A combination of stripping and concatenations involving Basic VDs of different sizes."

RAID Level Qualifier-0 "Mirroring across two extents"

Solution 2

Take a look: http://globalroot.wordpress.com/2013/06/18/megacli-raid-levels/

# Explanation of Raid Levels: 
['Primary-0, Secondary-0, RAID Level Qualifier-0'] = RAID-0
['Primary-1, Secondary-0, RAID Level Qualifier-0'] = RAID-1
['Primary-5, Secondary-0, RAID Level Qualifier-3'] = RAID-5
['Primary-6, Secondary-0, RAID Level Qualifier-3'] = RAID-6
['Primary-1, Secondary-3, RAID Level Qualifier-0'] = RAID-10

And match:

$ sudo /opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -Lall -aALL | grep RAID
RAID Level          : Primary-1, Secondary-0, RAID Level Qualifier-0
RAID Level          : Primary-1, Secondary-3, RAID Level Qualifier-0

$ sudo ./megasasctl
a0d0      136GiB RAID 1   1x2  optimal
a0d1      272GiB RAID 10  2x2  optimal

Solution 3

Since MegaCli is not terribly well documented we can at least compare outputs

My disks are in raid 10 (I checked in the bios)

from MegaCLI:

 RAID Level: Primary-1, Secondary-0, RAID Level Qualifier-0


                Versions
            ================
Product Name    : ServeRAID M5015 SAS/SATA Controller
Serial No       : SV13409496
FW Package Build: 12.12.0-0047


               Device Present
             ================
Virtual Drives    : 1 
  Degraded        : 0 
  Offline         : 0 
Physical Devices  : 6 
  Disks           : 4 
  Critical Disks  : 0 
  Failed Disks    : 0 

Comments

[cat pants]

Awesome, thanks! So I think my question is just a matter of terminology. What exactly is a "RAID Level Qualifier" ? (It seems like there should be just two raid levels here, primary and secondary, in this case there is extra information being provided which is somewhat confusing.)

[mfinni]

The doc has plenty of info. Look at all the different codes and descriptions for qualifiers - it includes important info for the RAID controller, not too much important info for the average person.

[cat pants]

The doc unfortunately does not include a definition of terms. In this case, I need definitions for the following term: "Raid Level Qualifier". What I meant by "extra information being provided" in my previous comment is the following: It looks like the RAID controller is saying there are THREE nested RAID levels, ie, "Raid Level Qualifier" being one of them. To further clarify my question here, here is an example of output I would expect from the controller: "Primary-1, Secondary-0" which would be a RAID 10. Does "Raid Level Qualifier" apply to the primary raid, the secondary raid, or both? :)

[mfinni]

Not sure what you're missing; the definition of RLQ is right in there. The document (on page 13, section 4.2, "RAID Level Qualifier) says it gives details about the primary RAID configuration. It's not a 3rd level of RAID. For you, with a primary raid level 1, you have RLQ of 0, which means "Mirroring across two extents." You could also have an RLQ of 2 with a PRL of 1, which would mean "Triple mirroring across three extents."

[mfinni]

Sorry, meant : You could also have an RLQ of 1 with a PRL of 1, which would mean "Triple mirroring across three extents"

[Hrvoje Špoljar]

These are not quite correct; RAID 10 is hybrid array; Primary and RAID level qualifier define RAID type of basic virtual drives (BVDs) which are then grouped (if more than one) as defined by Secondary; and secondary 3 means 'Spanned' which is combination of striping and concatenation since BVDs are not of same stripe count. So not RAID10; One of options to have Raid10 is same like RAID-1 in listing; but with multiple BVDs; other would be mirror of stripes Primary-0, Secondary-1, RAID Level Qualifier-0

[MadHatter]

I have no idea what RAID-13 is supposed to be. If you think it's a real concept, a pointer would be useful; otherwise, your answer is meaningless.

[arganzheng]

It was only a example...What if I take RAID Level : Primary-1, Secondary-0, RAID Level Qualifier-0?!

[MadHatter]

Beats me. But the example in your answer pretty neatly proves that you cannot just stitch a bunch of numbers in the output together and magically come up with the RAID level, don't you think?

[arganzheng]

Actually, use the RAID level and Span Depth info, you can determine the RAID level, trust me.

[MadHatter]

Trust you? No; that's not the point of an answer. If you want to show me, please do so, so I can upvote your answer. At the moment your answer shows me how I get RAID-13, which doesn't justify an upvote. Your answer will need to work for the example quoted by the OP!

[arganzheng]

see this post: serverfault.com/questions/595005/…

[arganzheng]

have you ever read the post carefully? That post have fully megacli output, which show you why it is RAID10 other than RAID 1?!

[MadHatter]

Your post, or the other, linked one? The other one seems to answer the question, and thus this question is a duplicate thereof. If you don't agree, please update your answer so it answers this question!