Trouble Formatting RAID 1 Array to ext4

[foobster]

Hello,

I'm trying to install SL6 to a pair of 2TB harddisks in a RAID 1 array. The problem is that when the "Formatting" progress window that says "Creating ext4 filesystem on /dev/mapper/pdc_eahgdeafbgp1" comes up it appears to eventually freeze. It's been like that for 6 hours without the progress bar moving at least. I have another identical system that I booted up using the gparted live cd to see if I could get any more information using that. I first created a 500MB ext4 partition and mkfs.ext4 ran almost instantly. I then tried 5GB and it seemed to take maybe about a second or two and worked fine. I then jumped up to 500GB and it's been running for about 5 hours now. I'm pretty sure that I remember the creation of an ext4 filesystem occuring extremely fast even for very large partitions, but this is the first time I've played with RAID.

Does anybody have any advice on what this might be or how I could give more relevant information?

[Rubberman]

I doubt that it is the ext4 file system specifically that is causing your problem. How did you create the RAID array? Was it in hardware, or are you using the mdadm software RAID capabilities of SL6. FWIW, my main workstation is running SL6, and I have 2 RAID-5 eSata arrays on it.

[foobster]

I'm using a ASUS M4A88TD-M motherboard which can set up RAID arrays through a BIOS menu. The gparted live cd sees it without issue and has no problem making small partitions. The SL installer also recognizes the drive fine but chokes during partitioning. I agree that ext4 probably isn't the problem but I wanted to be specific in my description.

Does anyone have any idea of how the time that mkfs takes scales with partition size? My naive guess would be something close to linear but I know very little. It just seems odd to me that it works with a 5GB partition but not a 500GB one. In the morning I will try taking smaller step sizes and see what that tells me. On a different note, could this possibly be a hardware issue? If the SATA connection breaks every few seconds for some reason would that explain why a small partition works but a larger one doesn't? I'm trying this on two identical machines and getting the same results though so that makes me think that it's not some sort of defect in any specific physical piece. The next thing I will try is installing on a single drive without RAID and the result of that should help narrow down the problem.

[HROAdmin26]

I'm using a ASUS M4A88TD-M motherboard which can set up RAID arrays through a BIOS menu.

This is called fakeRAID. You can increase your RAID resiliency by ignoring the BIOS "raid" and using the MD driver in Linux. That will allow the HDD's to be moved between systems and give you more insight into what the RAID set is doing - IE, you can use mdadm commands to see the RAID status, rebuild progress, etc. When you create a RAID1 set, generally the drives are initially sync'ed to ensure data integrity. This sync'ing will affect performance until it is complete.

* Yes, if you have SATA or I/O errors popping up in /var/log/messages, that is bad and could impair disk performance.

* If you have ~2TB disks, you may want to ensure you're using GPT partitions - MSDOS tables only go "up to" 2TB.