hdds under RAID 0 setup question

[daveleau]

I have 2 18GB WD 7200 rpm ATA66 hdds. I just repart./reformatted and reinstalled (haven't loaded drivers yet cuz I gotta sleep). Upon reinstallation, I noticed that my FastTrakk sees both drives and set up the striping array but windows 98SE sees all 34 GB. A 6.5 GB partition and a 27.5 GB partition. Should this be? Did I do something wrong int the setup? It is a modified Promise ATA66 with BIOS v1.08. Thanks for any assistance. I know there is at LEAST one guru out there with these. Just can't remember the name off=hand.
Thanks
Dave

[bdog]

It sounds to me like you have the drives in spanning mode instead of striping mode. In the Fasttrack BIOS, make sure that the "optimize array for" field is set to performance instead of capacity. Windows should just see 18gb if this is set correctly.

[Stan]

RAID0, that's a stripe... so it is totally normal that you have 36Gb of free space.
The data is broken down into blocks and each block is written to a separate disk drive.

At home, I have a RAID0 array with four 9.1Gb HD, and the total disk space is 36Gb !

You would see 18Gb in a RAID1 (mirror)
Your setup looks OK for me !!!
The problem with RAID0 is if you loose one HD, the entire array is gone !!! all data lost...

Stan

[This message has been edited by Stan (edited 04-19-2000).]

[bdog]

Stan is probably right. He is the RAID guru. I only use raid 1 (mirroring) It gives you data redundancy with a capacity of the smallest drive in the set. Striping gives you increased performance using two or more drives. I thought the size was also the smallest of the drives in the set since it reads from both drives, but apparently not.

[Stan]

Hey Bdog, you are right when you say that the stripe size is set up using the smallest size of the HD.
For ex, if you use one 9Gb and one 13Gb HD in a RAID0 array, you will have a array of 18Gb (2 x the smallest HD). So, you loose 4.5Gb of the 2nd HD.
But, in Daveleau's case, he is using two 18Gb HD, so the RAID0 array will be 36Gb

Stan

[This message has been edited by Stan (edited 04-19-2000).]

[Mntsnow]

Yep...Raid0 is stripe. I have 2 20.4 maxtor drives and it is seen as 1 "40 gig" drive when setup that way (really a bit smaller as we all know how they "size" drives unformated)

Stan are you really using all 4 drives in stripe or are you running a raid 0+1 setup?

Mntsnow

ps. Welcome back from California Bdog!

[Stan]

Yep... four HD in RAID0...
To be more precise, I have four IBM 22Gxp (7200 rpm, 2Mb cache), the 1st 2 are 9.1Gb and the last two are 13.5Gb.

BTW, I am using 2 FastTrack RAID controllers for that setup.
It runs like a dream...

Stan

[Mntsnow]

Sweet http://www.sysopt.com/forum/smile.gif

Mntsnow

[daveleau]

Thanks guys. I RTFM but got confused on mirroring and striping. I thought that in a stripe, you would only have one drive with two copies and it would read from both, increasing performance. I understand now though. Thanks!

Mntsnow- Yeah my drives are 18GB but seen as 17GB, hence the 34 GB total. Thanks

In the Fasttrack Util on bootup, it says that they are setup for Perfomance (striping) and the computer type is set to server. I assumed this was a better choice than the Desktop option. Oh and it does show up as functional.

Dave
Dave