No RAID5 on the X4200 SAS Controller

To my surprise, the LSI SAS RAID controller in the X4200 doesn’t support RAID5. I incorrectly assumed it must, since there are four drives bays. Assumption… The root of all evil in sysadmining. Instead I can configure two drives as a RAID1 array (with an optional hot spare) or stripe 2 to 4 of the disks together. Hmrf. Not exactly what I had in mind.

Is it just me, or would a 4 disk RAID5 set not be a common config?

I could probably use software RAID, but I instinctively fear software RAID boot/root volumes on x86 hardware.. Maybe it’s time to do a little testing and see what my options are in Linux and Solaris.

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Published:: 03.29.06 / 11pm

Category:: solaris, storage, x4200

7 Comments

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neil corlett 03.30.06 / 4am

well, in about 3 - 4 months we will see the production release of ZFS. that won’t help with bootable partitions though.

there will be a bootable ZFS at some point. it looks to be considered important. mailiing lists indicate Great Things are afoot in install, patching & packaging, levered off ZFS checkpointing and other features.

it’s hard to know if the firmaware in LSI is more reliable than the code in solaris…
ux-admin 03.30.06 / 4am

RAID1 0 with SVM UFS is extremely reliable on the i86pc platform.

I’ve subjected my Solaris i86pc workstation to a lot of very violent crashes and never lost any data on the mirrored boot disks.
Jason Hoffman 03.30.06 / 8am

Yeah I had noticed that when reading the whitepaper (and during a recent obssession with sas raid controllers).

A 4 disk RAID5 is extremely common but they’re just using a SAS “controller” with “Integrated RAID™” (meaning RAID1 or RAID0). This is LSILogic’s “low cost RAID” solution that’s included in the straight controllers. Their controllers expanders is what people are using to build SAS/SATA JBODs that are wired up and hooked into a server with a real hardware RAID card.

What they should have done is spend a bit more and put in the MegaRAID SAS cards (which if you feel like putting one in and rewiring the inside, they work fine).
benr 03.30.06 / 4pm

Thats a really kick ass photo Mark.
mark 03.30.06 / 6pm

Thx for the comments folks. Clearly Sun is imagining that anybody “serious” will attach to some network storage. Which is too bad, cause a 4 disk RAID5 would be handy on this box, especially when 146GB SAS drives arrive.. I wonder how much cost the MegaRAID SAS card would add?

ux-admin: I didn’t even know you could do a mirrored UFS root on x86! I use SVM mirrored boot disks on our Sparc boxes (and have for a long, long time). I’ll have to try it out. Both of these boxes are going to be os-neutral app servers so they can run any OS really.
Andy 07.18.06 / 11am

I believe LSI Logic Megaraid SAS 8300XLP (ZCR card) will give full RAID support for x4200.
Wayne 04.30.08 / 11am

I must say this all sounds awesome, but how the heck do I set this all up. I have two x4200’s and I always get errors like my slices overlapping.

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VMUNIX Blues is written by me, Mark Mayo, in Vancouver, BC. I like unix, coding, and the web, and naturally most articles I write here have something to do with what I like. If commenting on an article isn’t your style, you can always email me — mark (at) vmunix.com.