Very noob LSI / MegaRaid question

[james23]

hi,

Ive just recently been getting into LSI / MegaRaid HW raid cards and thus MegaRaid Storage Manager. Prior ive always used adaptec HW raid cards. Maybe im missing something obvious, but is it not possible to mix RAID 5 and RAID 6 (example) arrays (or VDs as they are called in LSI) on the same set of disks?

I often do this on my adaptec cards. for example, lets say i have 6 x HDDs (2tb drives for example) attached to my 9271-8i card, is it possible to have a 3TB RAID 5 array, and also a 2 TB RAID 6 array on these same 6x HDDs? Or must i choose one RAID type and stick to it for all VDs created on these 6x physical HDDs?

here is the line from the LSI MSM (MegaRaid Storage Manager) that is driving me crazy:

NOTE Having virtual drives of different RAID levels, such as RAID 0 and RAID 5, in the same drive group is not allowed. For example, if an existing RAID 5 virtual drive is created out of partial space in an array, the next virtual drive in the array has to be RAID 5 only.
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What im asking, is can you have a RAID 5 and a RAID 0 and a RAID 6 on the same set of disks? On every type of RAID card ive used so far this is possible (adaptec, arcea, hpt, even old promise cards ), but it seems on LSI you can *not*. this is going to be a huge issue if its not possible as i often have different raid types on the same set of disks in order to maximize disk space usage..

Thanks!

 

[rsq]

James,

I just tested on my small LSI raid card. (8 channel, can only do r0 and r1) and it is not possible for me.

I don't know what card exactly you have, but for me it was no go.

Best regards, Erik

 

[james23]

here is another, maybe better example of what i want / why i want this feature (and cant believe that LSI does'nt offer this):

on my adaptec 5405z, i have 4 x 100gb SSD drives connected. i have:

1x 80gb RD6 (4 x ssds) for my OS boot drive (win 2008 r2)
1x 60gb RD6 (4 x ssds) for some VMs boot (vmware workstation)
1x 26gb RD5 (4 x ssds) for a plex database ( i can somewhat easily recreate this db, but id rather not loose it if i happen to loose 1 SSD drive, yet i need a bit more space than would be available if i made this a RD6 array, thus i used RD5)
1x 90gb RD0 (4 x ssds) for use as a scratch drive (its really fast, i put temp data on this or use it for benchmarking), i also use this raid 0 array as the location for my windows pagefile.sys (the virtual memory file).

this would not be possible to do on a LSI card, i would have to go ALL raid 6 arrays, or ALL raid 0, or ALL raid 5 arrays. the same exact concept is applied to my larger disk arrays, i dont want to be locked into just one type of RAID type, as this will result it lots of wasted drive space.. id rather have 2 x raid 6 arrays on 2x separate disk groups, than 1x HUGE rd6 arrays (or a few arrays) all the the same disk group. idea being, if i loose 3 drives on that set of disks i loose all of my rd6 array contents versus having to loose 3x drives on one set of disks AND 3x drives on another set of disks to loose all my raid 6 contents.. :~~~(

How is it that i get this, but LSI DOESNT?!?! there MUST be others out there in the same situation??

 

[jkerr2]

I have a few LSI raid cards at work and 1 at home. Its entirely possible to mix raid levels on one card. (probably depending on the cards. I have 9260 series) I have a raid 1 for the boot disk and a raid 6 for storage. I just created the boot disk on the first virtual raid 1 drive. Installed windows server. Then installed megaraid and installed my drives for the raid 6. Created a new raid 6 virtual disk and formatted it. I am pretty sure the boot utility on the card will do the same thing.

 

[dandragonrage]

I have a few LSI raid cards at work and 1 at home. Its entirely possible to mix raid levels on one card.

He's talking not just same card but same drives... He wants to allocate part of EACH of his drives to one array and part of EACH of the same drives to a different array with a different RAID level.

This is probably not possible but I never looked into it deeply with LSI stuff.