Linux HW and SW RAID Benchmarked

An anonymous reader writes "A Norwegian site has written up an article with various RAID solutions benchmarked using both bonnie++ and dbench. The result shows a lot of surprises, especially when comparing low end sw RAID with high end hw RAID. The text is in Norwegian but the numerous graphs are self explanatory. It does look like a few kernel drivers need a little tweaking."

Comments

Heh

[FlyByPC]

My bonnie++ was used by Norwegians, To see how fast my RAID could be, My bonnie++ was used by Norwegians, ...but was bonnie++ written in C?

Damn...

[broody]

Damn. I've been a geek too long. After all these years I know understand how my pointy haired boss feel when attempting to read a technical article.

Time to troll

[Afrosheen]

Ok, who the fuck allowed this submission to go through? A whole 2% of Slashdot readership will probably be able to read this, the rest of us are left in the dark. Are longer bars better, or worse? WTFOMGBBQ?!

Re:Norwegian

[wfberg]

Anyone know an internet translator that supports Norwegian? Or even a Norwegian? It would be nice to have a translation so we don't have to sit around making uninformed comments about what we can't understand...

I think "Jeg vil rette en advarsel til alle dere som skal ut å handle kontrollere etter dette. Sjekk_nøye_om kontrolleren er støttet av kjernen! " speaks for itself.

Re:Norwegian?

[dm(Hannu)]

A møøse once bit my sister...

Translation of their conclusion:

[Nichotin]

Ok, here is a rough translation:

I have wanted to test some real SATA controllers against SCSI controllers for some time now, to see how good SATA has become. I once thought that cheap controllers like Sil 3114 is cheap crap that manufacturers put on their boards simply to provide SATA-support, and that software RAID was a cheap, but insufficient solution, since I have followed the principle that hardware does the job best. "A more expensive controller, means more hardware", was my initial guess, but it seems that even the cheap controllers are worthy. Software RAID also performs very well. SATA is no longer some gag for disk systems that are supposed to perform well, and many myths have been dispelled by my test.

I will not go as far as to say that you shall place your bet on cheap controllers or software RAID. The reason is simple, in a expensive controller, there is much more functionality, that a cheap controller can just dream about. Functionality like hot-spare drives and hot-swap, just to mention some. I do not want to recommend SATA over SCSI in a while either. The lifespan of a SCSI drive is in most casese many times as long as a vanilla SATA-disk. When you choose a solution, it should last. If you have machines that has a big fat controller, RAID50, then SATA might be something for you. If you have a machine that needs redundancy on the internal drives, but where changing controllers, or even buying them in the first place has been in the way, then software RAID might be the solution for you.

I shall be careful to mock the LSI controller, as I think there might be a problem with the way the test machine talks to it. I think the new Megaraid driver in the kernel might be the problem. Either it needs to mature, or it is simply that it does not like 64-bit Linux. I have not tampered too much with the default settings, but it runs superparanoid verification algorithms when it sends and recieves data. I have not fleshed the BIOS on any of the controllers.

Adaptecs controllers do very well. Everything was not perfect with them, and the aacraid driver in the kernel was too old for both of the controllers. From their website, I found something that looked like source code (Adaptec seems to rely on 100% RPM based distros), and I could bouild my own module. After that, no problem. A little minus is that the aacraid does not report how long the controller has gotten in building the array after you have set up a RAID. By looking at the SCSI-BIOS after some hours, I got to verify that the array was built.

I want to warn everyone that is going to buy a controller. Carefully check that the controller is supported in the kernel! I use Google to check for references to the card on mailing lists, but that does not help much when you have Debian, and all that exist is binary RedHat drivers.

Now, run to your console and test your disk system. This test does only give you indications on what to choose. I allow myself to give you one final advice: Run tests for yourself.

Re:I think that the results are obvious

[tap]

Second is the higher spindle speeds

You can get 10k SATA drives now. There are 15k SCSI drives, but they have small capaciticies and are very expensive. There are a small number of applications that actually want to use them. For most uses, a 300 GB 7200 RPM drive is better than a 73 GB 10,000 RPM drive that costs four times as much.

Third is SATA only lets you have *one* drive. SCSI lets you have 15.

You're off in two ways here. One is that your ignoring the topology difference between SATA and SCSI. SATA uses a star, you have a controller with multiple ports, with one drive on each port. SCSI use a bus, with a single port controler and multiple drives on each port. The star topology is a lot nicer in many ways, one of the reasons twisted pair ethernet with hubs replaced the bus like coax ethernet. Secondly, you can't connect 15 drives to a single SCSI bus and run at ultra-160 or ultra-320 speed. You're only allowed to connect something like 4 drives to remain in spec at those speeds.

A 3ware 12 port SATA card and a three port U320 SCSI card with four drives on each port both support the same number of drives. Except the SATA card will probably be 1/3 the price, the SATA drives will be 1/10 the cost per GB, and have higher transfer rates.

SATA does have real command queuing. There are real hotswap SATA drive bays. It's true the cables can't be as long, but since you only need to connect once device per cable instead of 4 or more, it's usually easier to connect. And believe me, I know my way around a SCSI cable.