How Many Drives On a Raid?

[joek71]

Hi guys I have a question I have a KG7-Raid mobo, I currently have two 30Gig hard drives, how many more can I put on my raid to expand the space?

Thanks,
Joe

[sptw]

I assume you're talking about Raid0, then the maximum is four.I advise you that you can reduce the performance with 4 hds, first because this mobo has a 133 MB/s of bandwidth on PCI bus, each HD can perform 40-50 MB/s totalize 200 MB/s.Don't forget that are other process running in background, as sound, drivers .......Second, IDE controller can't manage master and slave at same time.The IDE controller can do it on different channels, but not in the same channel, then it can reduce the performance too.It's better to buy two big than four small, in this case of course.Now, if it doesn't matter for you, try to buy the other two disk from the same brand and with same specifications.

[lechumbl]

Hi Joe,

You can put as many as you want, as long as they are the same size. If not, ALL the drives will be listed as the size of the smallest size drive.
This info is valid if you have a hard drive farm.
If you are running off the raid on the mobo, only as many drives as you have connections for.
You have two RAID on board connections, therefore, you can run two drives off of each one, total of 4 drives.

Take care.....

[joek71]

thanks, i am currently running raid0,if i get 2 more 30gig drives and connect them, what will windows see? will i expand the current size or will the new ones be seperate from current size?

[sptw]

Windows will see 120 GB.

[Drake]

133 MB/s of bandwidth on PCI busI don't know much about RAID or storage in general, but why would the PCI bus be used?

reduce the performance with 4 hdsWould running 4 HDs as two different RAID drives solve this? Or would the performance still be degraded due to the extra drive on the RAID channel?

[sptw]

Hi Drake :)

I don't know much about RAID or storage in general, but why would the PCI bus be used?

In short words, PCI is an interconnection specification for computer components.PCI is basically a 5 volt, 33MHz, 32-bit bus with a basic data transfer rate of 133 Mb/s.PCI also has others options which can be combined in 64-bit bus extension - basic data transfer rate of 266Mb/s and 66MHz extension - doubles basic data transfer rate.Devices are conected to PCI bus. AGP is simply an extension of existing PCI technology too.The IDE controllers and in this case that we are talking :Raid controllers: are conected to PCI bus.This is why devices are limited to bandwidth of PCI bus.Devices tend to share this bandwidth.

Would running 4 HDs as two different RAID drives solve this? Or would the performance still be degraded due to the extra drive on the RAID channel?

No, it can not solve the problem.You're still limited to 133 Mb/s and for the characteristics of the IDE controllers.In the JoeK71'Case, KG7-Raid use a HPT372 Raid controller, that has only two channels, then you can put 4 drivers of course, but in master/slave configuration, and IDE controller is not smart enough to manage it in the same time.This is why SCSI is prefered in the server situation.The things change a lot with server boards that use to have a 64bit/33mhz or 64 bit/66 mhz expansion slots, because it has more bandwidth, 266 mhz or even 533 mhz.Well, things could be a little different, not so much, if the the Raid Controller was a four channels, but still limited for 133 Mb/s.Probably you could get a better performance when compared to 2 channels device.

[mdzcpa]

Wow...nice explanation sptw! Spot on:)

[Drake]

Thanks for clearing that up ^.^

[NOHTO]

I never knew that. That explains why when I had 8 20 gig Maxto 7200 ATA133 drives on a striping 0 array it semed slower than dogsh!t. (I was using the Abit AT7 with the Hpt. 374 controler)

[mdzcpa]

Originally posted by NOHTO
I never knew that. That explains why when I had 8 20 gig Maxto 7200 ATA133 drives on a striping 0 array it semed slower than dogsh!t. (I was using the Abit AT7 with the Hpt. 374 controler)

Yep....VIA chipsets as of late have been known to have a rather outdated PCI bus design which is easily bottlenecked by todays components which use the PCI bus.

There are some "fixes" out there which help...like George Breese's PCI Latency Patch, and BIOS settings like "Enhance PCI Performance" which have recently began appearing to combat the issue.

[NOHTO]

I was using VIA's raid patch to no avail.