Mixing SATA & SAS on an SAS3 Backplane

BecauseScience

[H]ard|Gawd
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Oct 9, 2005
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I bought a Supermicro SC847 with SAS3 backplanes. My hba is an m1015 but I plan to upgrade to an SAS3 hba at some point. My disks will always be used in JBOD mode. I can't see myself ever using hardware raid.

I have a bunch of consumer SATA disks but I need more space and I'm looking at enterprise disks. The price premium to go enterprise isn't that big at the larger sizes.

Should I stick with SATA or move up to SAS if i decide to get enterprise disks?

Is mixing consumer SATA disks and enterprise SAS disks a good idea? Bad idea?

Suppose I've decided on the 8TB Seagate Enterprise Capacity disk. It comes in both SAS (ST8000NM0075) and SATA (ST8000NM0055). Would I see any benefit from going with the SAS version?

What benifits of SAS disks might be lost because they have to share an expander with SATA disks?

Anything anyone has to say on the topic will probably help.

FYI: My current disks are a mix of ST4000DM000 and the dreaded ST3000DM001.
 

Stereodude

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Well, you can't really "mix" them at the hardware level. Hardware RAID cards, which your HBA isn't, generally won't let you make an array that containing both SATA + SAS drives. However, you can connect both simultaneously to a single card.

Personally, I'd look at enterprise SATA drives myself and skip the enterprise SAS drives. Off the top of my head I can't think of any benefit the SAS drives will have over their SATA fraternal twin.
 

BecauseScience

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Well, you can't really "mix" them at the hardware level. Hardware RAID cards, which your HBA isn't, generally won't let you make an array that containing both SATA + SAS drives. However, you can connect both simultaneously to a single card.

There is some "cooperation" that happens when SAS & SATA share a backplane. It's not the same as when they each have their own direct channel to the hba. The SATA stuff gets encapsulated by some SAS protocol that I don't know much about.

Why? I view them as less compatible. You can put old / spare enterprise SATA drives in a spare systems connected to the motherboard with adding a SAS controller. You can't do that with SAS drives.

I don't care about re-use in other systems. Disks go into my nas and only come out when they're dead.

However, I have a pile of spare m1015's that I can stick into other systems if I really, really, really want to run SAS disks in them.
 

XxDaRkReAp3rxXdOtCoM

My User Name Is Stoopid
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Why? I view them as less compatible. You can put old / spare enterprise SATA drives in a spare systems connected to the motherboard with adding a SAS controller. You can't do that with SAS drives.

Superior protocol and I'd use them RAIDed instead of JBOD so wouldn't have much use connecting it to a spare system either way. Too annoying if a drive dies since you have to restore it from backup and lose that data for however long it takes to replace the drive and restore. The guy already has an SC847 - at that point I'd go with NL-SAS drives (RAIDed) and a RAID controller with 1-2 GB cache that's battery backed. Anything else is just half assing it with such a nice chassis.

Edit: It would be like sticking a consumer motherboard in there without ECC RAM and like an i5 or something.
 
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