PCI RAID card? Sil3114

[burn-e86]

right then i'm planning on buying a SATA PCI card so i can create a RAID 5 array. The card it self is this one
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=013&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=230088568718&rd=1&rd=1
the only thing i'm concerned about is the fact that its 32bit/66Mhz. i cant really remember what the normal speed for PCI is so does anyone have any infomation on PCI standing speeds and performance levels? i.e. would it be slower then my onboard connectors?

my mobo is an asRock 939dual-sata2

 

[yamla]

Note that this card doesn't do hardware RAID5. It's all handled in software. As such, if your motherboard already has support for RAID5, it'll likely be about as fast.

You can read about PCI at http://en.wikipedia.org/wiki/Peripheral_Component_Interconnect

Given that this is software RAID, you almost certainly won't be limited by your PCI bandwidth.

 

[darkstar782]

Normal PCI speed is 32bit 33MHz.

That card will work at 33MHz, just with only 133MB/s bandwidth.

Like the previous guy said, RAID 5 on this card will be comparatively slow and have a high CPU overhead.

 

[burn-e86]

well the card runs at 32bit/66mhz so should run at 266MB/s
and to be perfectly honest with you guys if I remember a Hardware RAID setup is bitchin expensive. but what sort of hit are we talking about in performance wise? the only article i could find was pretty dated http://tomshardware.co.uk/2004/11/19/using_windowsxp_to_make_raid_5_happen/index.html
and doesnt show reletive CPU usage.

 

[darkstar782]

The card will NOT run at 66MHz in a standard motherboard. Your motherboard will NOT support this.

If you want 32bit/66MHz you need a PCI-X motherboard, a server class board.

You can expect your array to perform similarly to the software array in those benchmarks. 133MB/s will be a hard limit however, not forgetting that the 133MB/s is shared with all PCI devices you have.

As well as the performance limits, the array will slow down drasticly any time the CPU is in use. Expect your transfer speeds to half when playing games for example.

Writing to the array will use 70-85% of a single core CPU.

To be honest you are best with RAID 0, RAID 0/1, or single drives. RAID 5 is not a good idea without a hardware XOR controller.

 

[burn-e86]

hmm...this is useful news to me...so i should only really use a RAID5 with atleast a dualcore processor?...well an XOR controller
i would just use them seperately but i've had too many drives fail on me and if i use RAID 1+0 then i loose 2 drives worth of storage whereas RAID5 its only 1. but then again i'm thinking of putting this into a Media server, so the high CPU overheard wouldnt be too much of a problem since it would be a secondary storage and only really running Win2000 server with Utorrent or something like that.

 

[yamla]

For what it's worth, I used to run software RAID5 in Linux and now run hardware RAID6. But just pretend I'm running hardware RAID5 for the rest of this.

My understanding is that Linux has a much better implementation of software RAID5 than the Sil drivers or than Windows itself.

That said, software RAID5 in Linux was PERFECTLY USABLE on my dual-core machine. In fact, it was quite fine back when I had a single Athlon64-3500. For day to day development work, it wasn't significantly slower than my current hardware setup.

This sounds like heresay. And certainly, I can show you several benchmarks that show my current solution can read data as fast and write data much faster. And my CPU usage is certainly lower.

But the fact of the matter is, hardware RAID5 is only going to be faster on writing, something people don't actually do all that often. And even then, chances are you can spare your CPU for a bit of effort. It all depends on what you are using your computer for, though. If you are using it to rip and recode DVDs, software RAID5 is going to seriously hurt, for example. And this all depends on software RAID5 being implemented efficiently; it was in Linux but may not be in Windows.

That said, software RAID0, RAID1, or RAID10 is going to be MUCH MUCH more efficient when it comes to speed and CPU usage. It takes virtually no CPU whatsoever and is trivial to implement. A 4-drive RAID10 solution gives you as much storage as a 3-drive RAID5 solution and may be a better alternative.

(For the sake of record, I have a 6 drive RAID6 solution)

 

[burn-e86]

well what i'm planning on doing is having is an atholonXP 2800+ with either an abit NF-7S and an 80Gb hdd for the OS with a RAID 5 added for shared storage. the reason I want a seperate hdd for the OS is so i can switch out the Hdd for whatever. but if i build the array in XP and switch out the OS will it still function? I'm guessing no but i do want to pass it through u guys before making any assumption.
also since the Software RAID isnt my primary will the performance really matter THAT much?