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NOT a noob question about RAID?!?1 WTH?! win2003 and 2+ TB raid

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October 11, 2007 4:12:24 AM

okay, i got myself into a BIT of a bind, i think i know the way out of it, but i'd like to hear what YOU think. please only respond if you haven't asked "rate my build" or "is this psu okay?" or "will this card fit into this motherboard" in the past... well... ever...

the box is named Epsilon3 after the "great machine" in the tv show Babylon 5. it's my answer to my storage needs for the foreseeable future. built with future storange expandability in mind, it is housed in a 12u rackmountable server box with 25+ hard drive bays. it's running win2003 server ultimate. the rest of the details aren't necessary, suffice it to say that until last week it housed a rocketraid 2320 8 port SATA raid controller with only 5 wd5000ys 500 gig drives attached in RAID 5, giving it 2 terabytes total storage capacity. actually, functionally, 1.8 terabytes.

at first power on, it had 4 of those drives, i used the Online Capacity Expansion features of the card to add another drive a few months ago. simple really, add the drive, use the OCE to expand the array, go into disk manager and expand the partition to the rest of the available space.

the messed up part began when i added three additional drives last week.

i used the same procedure as before, the plan was to add the three drives to the array, filling up the 8 ports. leave 7 in the array and leave one for hot spare, giving the array a 3 terabyte capacity.
i added the drives, expanded the array. the card now read a total array size of 3 terabytes, i went into disk manager. it only showed an available extra space of 185 gig. i thought this was odd. probably against my better judgement, i expanded the array anyway. that's when i found my mistake.

i'd read and researched before hand, server 2003 can handle a single raid array of up to 64 terabytes with no problems. HOWEVER i didn't read the fine print closely enough. that is with DYNAMIC disks. with BASIC/simple disks it can only handle an array of max of 2 terabytes. that's what i had run into.

right now, disk manager will not let me convert the array to dynamic, nor does it see any more available space. so basically i have a 7 drive array, the card says it's 3 terabytes, the OS says it's 2 terabytes.

right now, my plan of attack consists of moving all the data off of the array, currently 900 gig's which wont be too much of a problem, just an annoyance. then, dissolve the array, removing it from disk manager. re-initialize the array, make the resulting drive in 2003 server dynamic, and then format it, hopefully reaching it's full capacity.

question is, does EACH DISK have to be a dynamic disk? or can i create the full 3 tb array, and make that dynamic if i do it that way first, instead of having it basic as i did previously?

has anyone had any experience creating a 2+ terabyte raid 5 array using 2003 server + hardware raid card? the things i've read suggest that if i do not have the raid card handling things, and just let the software raid handle it (which i'm not sure how to do, because that means i'd have to use the card as just more sata ports instead of raid and i'm not positive it has that capability) that i can make each one dynamic, and create a raid 5 from within 2003 server with all the disks. the way the card does it is that it combines the disks into a raid array and then gives that to the OS as a single large disk and i'm not sure i can make that dynamic.

anyway, if i keep going i'll just confuse myself.

what do you think?

Valis
October 11, 2007 9:37:22 PM

valis said:
please only respond if you haven't asked "rate my build" or "is this psu okay?" or "will this card fit into this motherboard" in the past... well... ever...


LOL. I got a kick out of that one. :D 

valis said:
i'd read and researched before hand, server 2003 can handle a single raid array of up to 64 terabytes with no problems. HOWEVER i didn't read the fine print closely enough. that is with DYNAMIC disks. with BASIC/simple disks it can only handle an array of max of 2 terabytes. that's what i had run into.

right now, disk manager will not let me convert the array to dynamic, nor does it see any more available space. so basically i have a 7 drive array, the card says it's 3 terabytes, the OS says it's 2 terabytes.

right now, my plan of attack consists of moving all the data off of the array, currently 900 gig's which wont be too much of a problem, just an annoyance. then, dissolve the array, removing it from disk manager. re-initialize the array, make the resulting drive in 2003 server dynamic, and then format it, hopefully reaching it's full capacity.

question is, does EACH DISK have to be a dynamic disk? or can i create the full 3 tb array, and make that dynamic if i do it that way first, instead of having it basic as i did previously?

has anyone had any experience creating a 2+ terabyte raid 5 array using 2003 server + hardware raid card? the things i've read suggest that if i do not have the raid card handling things, and just let the software raid handle it (which i'm not sure how to do, because that means i'd have to use the card as just more sata ports instead of raid and i'm not positive it has that capability) that i can make each one dynamic, and create a raid 5 from within 2003 server with all the disks. the way the card does it is that it combines the disks into a raid array and then gives that to the OS as a single large disk and i'm not sure i can make that dynamic.


OK. First, yes, I've built two 2+ TB arrays under Windows Server 2003. The one I built at work is a 9TB array on an iSCSI SAN unit, the other is at my house. I have a server not quite as sophisticated as yours ;)  but it gets the job done. I have a 3TB array on it (5x750GB drives on a 3Ware 9650SE), running Windows Server 2003 R2.

First, there are a few questions:

1. Is your Windows Server 2003 installation updated to Service Pack 1 or higher? I will assume yes.
2. Is your boot partition (C: drive) on the RAID 5 array? I will assume no, that it is on a separate drive.

If those two questions are as I assumed, then solving the problem is simple - you need to convert the MBR-partitioned RAID 5 disk to a GPT disk. GPT disks enable partitions >2TB.

In Disk Manager, right-click the drive number on the left hand side of the graphical section (where it says "Disk1", "Basic", "Online"), and choose Convert to GPT Disk.

Once the disk is converted to a GPT disk, you will now be able to expand the partition using the command-line DISKPART utility. Obviously, don't attempt to expand the partition with other tools, like Partition Magic or GPartEd, as they don't know how to handle the GPT disk format.

If you are booting from the RAID 5, you will need to fix that first. Standard IBM-BIOS machines cannot boot from a GPT disk. You will need to install a small hard drive on the motherboard disk controller and move your boot partition to that using Partition Magic or GPartEd so that your RAID 5 becomes a data disk only.

For more information, see the Windows GPT FAQ.
October 12, 2007 12:24:31 AM

Love the answer SomeJoe7777 and i agree entirely...

me also owning a Server2003 64bit system using a 2TB array (5x500WD on Adaptec 3805). Its a good thing to know. On a side question, however, seeing as you are well in the knowhow...

Because GPT is a "newer" standard, it is not backwards compatible with legacy systems ie. even XP Pro will read it incorrectly. Does this cause any issues with access over a network or is it limited to the machine the GPT disk is running on, in which case my Server2003 64bit would be fine and my networked XP Pro 32bit machines can still access over the network the same as always?

Sorry didnt mean to hijack your thread valis
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October 12, 2007 1:41:44 AM

chookman said:
Because GPT is a "newer" standard, it is not backwards compatible with legacy systems ie. even XP Pro will read it incorrectly. Does this cause any issues with access over a network or is it limited to the machine the GPT disk is running on, in which case my Server2003 64bit would be fine and my networked XP Pro 32bit machines can still access over the network the same as always?


No, there are no issues with network access. One part of the 2TB limitation is the MBR partitioning scheme on the physical disk - MBR cannot describe partitions where the last sector of the partition extends past what a 32-bit number can describe (2^32 512-byte sectors = 2TB). Another part is the standard disk drivers in Windows XP x86 (32 bit) and other legacy OS's that are written with that limitation in mind, and cannot access those sectors either, even though the disk controller hardware might allow it (i.e. 48-bit LBA support for IDE/SATA, 64-bit LBA/16-byte CDB support for SCSI). The newer disk drivers written for GPT support fully take advantage of the hardware's ability to access sectors past 2^32, and use the new partitioning scheme where partitions with sectors that lie beyond 2^32 sectors can be fully described.

Network access uses SMB/CIFS, which is basically a file system protocol. Because the client machine does not reference a physical device (it just makes a request to the file server, and the file server accesses the physical device) there is no 2^32 sector limitation present.

I have 30 Windows XP x86 (32-bit) client machines on my network at work accessing the 9TB array with no problems through a Windows Server 2003 R2 file server.

To prevent problems if you accidentally allow a legacy OS to see a physical device that is GPT formatted, the GPT disks contain what's called a protective MBR. i.e. there is a fake MBR written to every GPT disk that makes it look like there is one big partition on the disk that spans the entire thing. The partition type is 0xEE, which is an unrecognized partition type to almost all legacy programs. Generally, a legacy program (like Partition Magic) will refuse to do anything to a disk containing this unrecognized partition, thus protecting the GPT layout.
October 12, 2007 4:54:36 AM

More information than i needed, thanks so much makes understanding the limitation easy to understand :) 

Just love to learn hehe
!