Dell Workstation Raid: Software or Hardware?

Question

Looking at getting some Dell Workstations (T3500). One of the options is to raid 1 the harddrives (presumably this would give you a speed boost). Is this software or hardware raid?

Solution 1

http://www.dell.com/us/en/business/desktops/workstation-precision-t3500/pd.aspx?refid=workstation-precision-t3500&s=bsd&cs=04

"The T3500 uses an integrated SATA 3.0Gb/s host controller (part of the Intel chipset) and supports host based RAID 0, 1, 5, 10, an optional PCI-e SAS 6/ir controller supports SAS drives with host based RAID 0 or 1."

Hardware RAID I'd say.

Solution 2

We have discussed a similar question so here is a direct link to answer your question.

See these related topics too:

• How do I differentiate “fake RAID” from real RAID?
• Which One Better for My CentOS? Hardware RAID using Dell PERC 6 or Software RAID?
• When is RAID worth the trouble?

Solution 3

You absolutely have to look at the raid card specifications, especially for Dells. For example, I have a 745N storage server that has possibly the worst RAID card imaginable. I get a mere 2MBps out of it using some large file copies when I had it in a 4-drive RAID5 (the default). Switching it to a JBOD configuration with RAID5 in software and I get 20MBps. Still not fantastic, but a whole lot better. Searching google it appears lots of other people have the same problem.

Sometimes RAID cards are little more than BIOS tricks to write the same data twice. This is especially common in workstation motherboards. It may have been a good thing once upon a time, but as CPUs are insanely fast and RAID calculations are quite easy, you'll only see a minor load on your CPU (my server that uses raid1 sees a 1% additional load on average)

The easiest way to check is to try it - large file copy using your RAID card, and again using software RAID. See what's faster. If you don't have this luxury, find the type of RAID chip that is being used and search for it - you'll quickly find out whether its a so-called 'fakeraid' or real raid card (ie one that has its own dedicated processor). Toms Hardware will often have benchmarks, and the linux raid driver page has a list of 'fakeraid' chips.

Looking at the spec (and a quick google), x58 chipset is a fakeraid controller.

No doubt if Dell is building the system, it'll be the BIOS option to raid the disks. I'd go without. You can set 2 drives up in RAID1 after installation using Windows (or Linux) software raid. You might be able to set it up after-installation in the BIOS, but I'm not sure about that option.

Solution 4

Dells newer servers all have decent enough raid setups in Hardware. Generally only when you start looking at raid 10 or 01 that is becomes an issue. Some of their older cards were using tricks to get to a raid 10 level meaning losing a drive didn't always work as it should.

The T3500 does use HW raid on setup which is fine in a workstation. Monitoring for failures is easy enough in this situation.

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Comments

[Justin Scott]

I concur, hardware RAID. I have an older Dell workstation at home with hardware RAID 1 and it's worked without any trouble for going on six years.

[SpaceManSpiff]

For my own education, do you have a link that discribes in detail the differences in real raid vs fake raid? I read how the linux page describes the differences and I don't completely agree with it. While I do agree that the true hardware raid is better, I don't know that I'd consider a raid card that "OS driver and card's on-board flash BIOS provide 100 percent of the RAID capability" a software raid, to me this is more of a hybrid. I'd consider a software raid one where you are only using a standard card (no raid) and build the raid completely with the OS

[SpaceManSpiff]

I'm going to answer my own comment on this. From the Wikipedia RAID page, it does a better job describing the 3 types of RAID. Adaptec calls them HostRAID. So while not as good as Hardware RAID, I think this is better then software raid where the OS is controlling everything, you still get the advantage of it looking like a RAID to the OS at the BIOS level. Making a nice compromise between the two.

[Steven Parkes]

If it's fakeraid, it's software raid, as far as performance goes. All the chip does is tweak the bios so that, given the right drivers, it'll see some init info. But the driver does all the raiding in software. If you're running Windows, I don't know that you have a lot of choice. I've done this a fair amount on workstations and the result is definitely mediocre at best. When there is an issue, it's fragile to get back to reliability. If you're running Linux, I would do all the raiding manually with LVM and the md driver.

[Rob Moir]

Good point actually. I'm not a fan of software RAID at all but at least you know where you stand with it, as opposed to "is it real or is it fakeraid" hardware.

[SpaceManSpiff]

This is interesting, I haven't had an issue thus far and I hadn't been aware of the differences so I expect some of my RAID setups' have been the BIOS based ones. I can't say I've had any issues though and I test the machines before moving them into production by removing one of the drives while its running just after the OS is installed and then re-installing it the next day. No issues that I've noticed but I'll need to go back and see if these were BIOS RAIDs. Lower load servers so speed wasn't an issue for me. I'll watch for this in the future though, good to know. Thanks.

[Andrew Schulman]

This doesn't answer the original question, and the value of that question is doubtful anyway since it's 5 years old.