Software RAID setup by partition or by drive?

I've outgrown my ext FW drive that has served me well. May I still use it in a RAID 1 with a partition from a larger drive I am going to get?
I've spent the last few years backing up a TiBook to an ext FW 120GB Maxtor drive, which has worked well. I use SuperDuper to create the bootable backup every week or two and usually keep one or two old versions. It also holds my music and photo libraries, which are multi-GB.
With that said, I now have a MBP w/100GB int HD, so the 20GB partitions will no longer suffice. I've been thinking of getting a Maxtor 600GB RAID 0 as an upgrade. I like the speed but remain concerned about the risk of RAID 0. If SW RAID is by partition, it recently occurred to me that I can RAID 1 mirror the ext FW 120 GB drive and one 120 GB partition of the RAID 0 600GB dirve. Is that possible?
These appear to be the advantages: 1. RAID 1 on the backup, so if either the old drive fails or one of the drive in the RAID fails, the data is still fine. 2. Still get speed on the new RAID 0 ext. drive.
Please advise.
fellow

Hi fellow;
With the experience I have had supporting servers with RAID for IBM, I personally would try to find a different solution. I see too many variables, such as the buses and drives, to make me think it is going to be worth the effort. About the only RAID solution that were worthwhile were those that followed the rules.
Allan

Similar Messages

Will OSX software Raid-0 on external drive be regonized elseware?

Are RAID setups created in Disk util recognized in other computers. Say i have 2 external drives (over eSata on my 08 mac pro) in a raid 0 from disk util, can I plug these two drives into another mac pro and have them work?
Basically, are software raid setups from disk utilily readible from all macs?

Both systems would have to have their own controllers or ports, but yes, they should move and work just the same on both.
There are Port Multiplier cases and controllers, and there are the 2 ODD ports people use, or direct connect SATA external controllers.
You can even create a RAID internal or external and move it and it will work, or change the drive bay and order of your drives, the RAID will still work and be intact.
What often doesn't work are eSATA/FW or eSATA/USB cases.
Mac Pro Discussion focus on using and expanding is here:
http://discussions.apple.com/category.jspa?categoryID=194

Software raid on sata discs (solved)

Hi all.
I'm trying to set up software raid, following this guide: http://wiki2.archlinux.org/index.php/In … d-or%20LVM
My setup is sda & sdb.
/dev/md/0 /boot (sda1 & sdb1)
/dev/md/1 swap (sda2 & sdb2)
/dev/md/2 / (sda3 & sdb3)
/dev/md/3 /mnt/storage (sda4 & sdb4)
I'm running it as raid level 0 and reiserfs.
Partitioning the drives, setting up raid arrays, making file system, installing and configuring the system, copying the grub part, mounting devfs, proc and chrooting into /mnt works whit out any problem.
My problem begins whit setting up grub.
grub> root (hd0,0) (and other combos) gives me :file system unknown partition type 0xfd.
grub> setup (hd0) (and other combos) gives me :error 17 cannot mount selected partition.
I used to run an hda disc as swap & / and my sata discs as a large md/0 storage whit no problem, but after running hdparm -t on the devices, I thought why let it go to waste storing stuff that I don't use regularly.
/cat /proc/mdstat gives me:
Personalities : [linear] [raid0] [raid1] [raid5] [multipath] [raid6] [raid10]
md1 : active raid0 sdb2[1] sda2[0] 1959680 blocks 64k chunks
md2 : active raid0 sdb3[1] sda3[0] 17382144 blocks 64k chunks
md3 : active raid0 sdb4[1] sda4[0] 293041536 blocks 64k chunks
md0 : active raid0 sdb1[1] sda1[0] 192512 blocks 64k chunks
unused devices: <none>
both under the grub install session and booting up arch on my hda disk.
I disconnected my hda during the attempt to configure the software raid.
So if anyone knows what I'm doing wrong, please let me know.
PS: If the problem lies with grub and sata disks in software raid setup, I wouldn't mind making an boot partition on my hda and use the rest for a backup and important files drive, I just dont want to destroy my working arch install, just to find it wont work anyway.
Thanks.

If anyone is interested, I finally got it up and running with some small modifications.
Instead of whats in the wiki.
root (hd0,0)
kernel /boot/vmlinuz26 root=/dev/md/2 ro
I used.
root (hd1,0)
kernel /vmlinuz26 root=/dev/md/2 ro
(my sdb is detected as drive 0 and sda as drive 1)
And it works 8)

Software Raid and Kernel Panic (from wiki page) [SOLVED]

I am trying to setup a RAID 5 array using the instructions on the wiki:
http://wiki.archlinux.org/index.php/Ins … AID_or_LVM
I get through the instructions (have actually done it several times now) and get the following error:
io scheduler deadline registered
io scheduler cfq registered
FDC 0 is a post-1991 82077
RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize
loop: loaded (max 8 devices)
mice: PS/2 mouse device common for all mice
NET: Registered protocol family 2
IP route cache hash table entries: 65536 (order: 6, 262144 bytes)
TCP establised hash table entries: 262144 (order: 9,3145728 bytes)
input: AT Translated Set 2 keyboard on isa0060/serio0
TCP bind hash table entries: 65536 (order: 7, 786432 bytes)
TCP: Hash tables configured (established 262144 bind 65536)
TCP reno registered
TCP bic registered
NET: Registered protocol family 1
NET: Registered protocol family 10
Disabled Privacy Extensions on device c03f6580(lo)
IPv6 over IPv4 tunneling driver
NET: Registered protocol family 17
Starting balanced_irq
Using IPI Shortcut mode
VFS: Cannot open root device "md0" or unknown-block(0,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
The grub menu.lst
root (hd0,0)
kernel /vmlinuz26 root=/dev/md0 ro
I setup three partitions on IDE drives
/dev/md0 - root (8 GB / drive)
/dev/md1 - boot (100 MB / drive)
/dev/md2 - swap (1 GB / drive)
I have three drives for the area with three partitions on each:
hda1 - boot
hda2 - swap
hda3 - root
I did skip the LVM step in the wiki pages.
fstab
none /dev/pts devpts defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/cdrom /mnt/cd iso9660 ro,user,noauto,unhide 0 0
/dev/cdrom /mnt/dvd udf ro,user,noauto,unhide 0 0
/dev/fd0 /mnt/fl vfat user,noauto 0 0
/dev/md0 / reiserfs defaults 0 0
/dev/md2 swap swap defaults 0 0
/dev/md1 /boot reiserfs defaults 0 0
mkinintrd.conf
REMOVE_IDE=
REMOVE_SCSI=
REMOVE_SATA=1
REMOVE_CDROM=
REMOVE_USB=1
REMOVE_FW=1
REMOVE_RAID=
REMOVE_CRYPT=1
REMOVE_FS=
REMOVE_DM=
RAID_ROOT_ARRAY="md0"
RAID_ROOT_DEVICES="/dev/hda3 /dev/hdb3 /dev/hdc3"
HOSTCONTROLLER_IDE=
HOSTCONTROLLER_SCSI=
HOSTCONTROLLER_SATA=
HOSTCONTROLLER_USB=
FILESYSTEMS=
CRYPT_DEVICE=
ADD_MODULE=
REMOVE_MODULE=
The system is a dual PIII using the arch ISO 7.1 release.
Any thoughts on what is wrong with my setup? Or something I can try. I'm game for just about anything in my test environment to try and get it working.
Thanks,
Chris....

After the basketball games where over tonight I had a thought (and a little research). The install iso I was using was a pre-release of 0.7.1. When I downloaded the real mccoy and did a fresh install following the instructions on the wiki, all worked flawlessly!
Chris....

Moving Thunderbold DAS with software RAID 1 to different Mac

Background: I am preparing to wipe my iMac (currently Mavericks) to then do a clean install of Yosemite. Attached to my iMac is a "WD MyBook Thunderbolt Duo". This external "DAS" drive model is a single enclosure that contains two, 2TB physical drives, and attaches to the iMac with a single Thunderbolt cable. I am not using any WesternDigital software on my iMac! Instead, I have used Disk Utility to manage the drive and have created a single 2TB software RAID 1 array (HFS+Journaled) incorporating both of the 2 physical drives as slices. The RAID 1 volume mounts as "DAS" on my Desktop and currently contains the majority of my media files.
Before beginning the repartitioning, formatting, and doing a clean install of Yosemite on the iMac's internal HDD, I plan on disconnecting the DAS's thunderbolt cable so it's safe from the install process.
Question: What I need to know is what to expect when I eventually reconnect the DAS to the new Yosemite installation. Will my RAID 1 volume "DAS" simply mount on the desktop as expected?
What I don't understand is where software RAID slice and volume configurations are stored. Is the software RAID 1 configuration stored as part of the partition table on the drives themselves or is it stored on the Mac? I am hoping to hear that the software RAID configuration is all on the drives themselves and therefore the drive can be reattached to a new Mac and it will just recognize the configuration and mount the volume normally with no additional effort. Can someone please confirm this to ease my mind (or save me before I go ahead with this).
Sorry to put this in the OS X Server forum but I thought that a software RAID question using Disk Utility would be best answered from the expertise here.
I appreciate any info you can provide.

Yes the software RAID configuration is stored on the drives themselves so it will be safe to disconnect from one Mac and reconnect to a second Mac.
Note to others. Any Mac that supports Thunderbolt is going to be running a new enough version of OS X so as to not cause a problem.

Software RAID 0,1,10

With Mac OSX 10.5 there appears to be the ability to configure software RAID with multiple partitions. I am looking for some expert advice on using Mac OSX Server to achieve the backup of 5-10 Mac OSX systems (10.5 or earlier), striping and mirroring backup data from remote system to multiple drives and store common files (iTunes library) in a single location for all 5 licensed machines for single point access. The Mac OSX will be purchased if favorable response/support is provided to suggest this is the correct route. The other option is to source a NAS (network attached server); e.g. harddrive with ethernet connectivity and backup software.
Assumption: Mac OSX Server running on a dedicated Mac with multiple drives or multiple partitions.
Assumption: Mac OSX Server supports RAID 0,1,10 (striping & mirroring) and ability to serve common iTunes library.
Any expert advice or experience with OSX Server vs. NAS will be greatly appreciated.

Visited the Genius Bar and receieved all the answers to using RAID 1 for mirroring, centralizing the shared music/movie library, etc. Got all the answers for an effective backup, mirroring and server solution.

Raid Setup 890FXa

This is the first time I have tried to setup RAID or build a computer from scratch. I have been swapping parts for years but never built a system from scratch. My troubles are with setting up a striped RAID for the OS to install on. I have tried loading the RAID controller from the MSI boot disk which came with the board and a USB stick. I have tried loading the RAID drivers both before and after installing the OS. I have been unable to setup the RAID Controller. I have tried launching it before OS install, while in OS install and after install.
I can load Win7 and use software RAID but wanted to have the drives as boot drives with the OS installed on them for faster application access. I have searched the Internet high and low and nothing I do gives me the options of hitting Control F to enter the RAID Option ROM Utility. Inside the BIOS the only option for RAID is IDE.
Is there anyone on here who can give an 'idiots buid to setting up raid' on this board with a Windows 7 64-bit OS?

Me Again,
Making the changes in the sub-menu allowed me to setup the RAID array. Unfortunately, I am now experiencing more joyous setbacks. After setting everything to RAID I am receiving an Error msg during Win7 install.
I previously used the same OS install disk/hard drives/DVD player(s)/entire system to install win-7 64-bit on the same equipment without this error. Everything installs fine without RAID as boot array.
The current error occurs during Win-7 installation and states:
"A required cd/dvd drive device driver is missing. If you have a driver floppy disk, cd, dvd, or usb flash drive, please insert it now."
This error never occurred when I used the same equipment. I have searched for downloadable DVD player drivers for the drives but could not find drivers for either DVD player on-line (only firware updates). I also attempted to install specify the RAID Drivers (from MSI.com and MSI install disk/USB) and the install will not recognize the RAID drivers (I assume because it is looking for DVD drivers).
Do you have any helpful ideas as to what might assist with install to pass this error message?
Thanks in advance.

Striped software raid managed or referenced library

I am setting up a striped software RAID using a couple of internal drives on my MacPro in hopes of getting a little more speed out of Aperture 3. My question is should I keep a managed library on the RAID or should I keep a referenced library on the main startup drive and store masters on the striped RAID. Which would be faster? I am still using Aperture 2 right now and waiting to get an answer before I upgrade to 3. I plan to backup whatever is on the RAID to a Drobo.
Thanks of the help ya"ll

I would use referenced Even if you were putting both on the RAID. 2 drives Striped is not going to be a big benefit.
You will get more of a benefit putting your library on a separate drive than your raw masters and here's why. Raw files fall well into the category of Large block read speed that most current drives handle just fine, once it's read its in RAM so I usually don't recommend putting the RAWs on a striped raid of just 2 drives.
The real storage bottleneck is when the library is trying to write all of its filesystem previews and database changes to the drive concurrently as its trying to read raw masters at the same time.
If you understand Hard drive tech, you will know that For one volume to handle Small block random access read/writes and large block sustained reads at the same time is a recipe for a slowdown...
I'd put the Library on a dedicated SSD and your raws on your bigger internal drives.
Or... Just try putting the library on one drive and relocating the masters to another drive and see if you notice a difference first. I sure did!

Partitioning two drives to enable OSX and XP software raid.

Hi Guys,
I have found out that XP support software raid 0 so I am wondering if I can do this.
I have 4 disks in the bays.
Disk 1 - OSX System disk
Disk 2 - XP System disk.
Now I want to partition Disks 3 and 4 into 4 partitions and use OSX software raid on 2 of the partitions and XP software raid on the other two.
I am pretty sure that this is ok with XP, is it ok with osx as well?
Cheers
Andy

Hi AndrewCapon;
Could you please tell me exactly what you expect to gain with RAID? I notice that you have never told us what form of RAID you expect to implement here. Different versions of RAID provide different benefits.
I think this is the much larger questions. So often I find that users have totally unrealistic expectations of what RAID will do for them.
Also please be aware that RAID is in no way a replacement for backup. In fact if you use RAID for storage of your data a good backup plan is crucial.
Allan

3-Drive/4-Drive RAID setup questions

I'm contemplating purchasing a new 8-core Mac Pro. I understand RAID but I'm not an expert. That said, I'm thinking of doing one of the following but I don't know if both are doable:
One setup is 1 hard drive for Mac OS X, and 3 RAID drives for the video capture (3TB total RAID 0 Seagate 7200rpm drives).
Or, my question, can I just RAID 0 all 4 drives together and then create a partition for Mac OS X? It seems like this would give A LOT faster bootable drive, plus the benefits of seperating the media storage from the operating system.
The reason I ask now is this makes a difference in my purchase decision. If I can RAID all 4 drives together, do they all have to be the same capacity for RAID 0? If not, I'll just get a standalone 320GB drive for the OS, and RAID the other three 1TB drives together.
Last question, would it help to use a dedicated RAID card like the CalDigit card (or Apple card) instead of software RAIDing within Mac OS X?
Thanks in advance.

First off - DO NOT put your system on your capture RAID. No no no. bad bad bad.
Yes you can RAID your other three drives into a RAID 0 configuration using Disk Utility. All drives should be the same size. Recognize two things with this setup --
1. If your system crashes, you loose the RAID partition as it is created and maintained through system software.
2. If you loose one of the three drives, you loose all the information on all three drives.
A more secure way to go is with a hardware RAID controller. Apple sells one with the MacPros and Caldigit has one as well.
With the Caldigit you can set up the 3 drives as a RAID 5 which will give you data security. I'm not sure what RAID configurations beyond 0 the Apple card supports.
Good luck.
x

Adding A New Drive To A Software RAID 5 Array

Edit 3: Just mounted the partitions and I can delete them because they contain nothing special. Is it safe to expand the 2nd partition of each drive to fill up the left over 22 GB?
Edit 2: I just deleted all the partitions off of my new drive and created one partition, then added it to the array and it works just fine. My next question is, can I delete all the smaller partitions and expand /dev/sd[x]2 to reclaim all the space (about 70 GB)?
One of my drives failed and Western Digital sent me a new drive, except it was an external drive instead of an internal drive, so I cracked it open and the label looked different. Turns out it's just refurbished and it's the same model as my other drives (WD Caviar Green 3 TB).
I've read through the wiki article on Software RAID and created the partitions exactly the same as my other drives, but while creating the main 2.7 TB partition it says that the ending sector is out of range when it isn't. I'm new to all this so I have no idea what to do. From what I've read there normally aren't this many partitions per disk, correct? I also have md124, md125 and md126 for the other partitions. md127 is for the 2.7 TB partitions. I took the array out of my Thecus N4520. I have a 3 TB external drive and a 1TB internal, along with another 500 GB drive. Would I be better off at destroying the RAID set and creating a fresh RAID 5 set, considering I'm losing about 90 GB if I don't need the smaller partitions.
/dev/sdc
Disk /dev/sdc: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00636413-FB4D-408D-BC7F-EBAF880FBE6D
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
/dev/sdd
Disk /dev/sdd: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): C5900FF4-95A1-44BD-8A36-E1150E4FC458
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
/dev/sde
Disk /dev/sde: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 2B5527AC-9D53-4506-B31F-28736A0435BD
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
new drive: /dev/sdf
Disk /dev/sdf: 5860467633 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 93F9EF48-998D-4EF9-B5B7-936D4D3C7030
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860467599
Partitions will be aligned on 2048-sector boundaries
Total free space is 5813281700 sectors (2.7 TiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00 Linux RAID
2 47187968 47187969 1024 bytes FD00 Linux RAID
3 46139392 47187951 512.0 MiB FD00 Linux RAID
4 2048 20973559 10.0 GiB FD00 Linux RAID
5 20973568 41945071 10.0 GiB FD00 Linux RAID
when I type in 5860491263 as the end sector gdisk does nothing, just wants more input. If I type +2.7T it accepts it, but really it just creates a partition that's 1KB in size!
I am able to create a 2.7 TB partition with an end sector of 5860467599, this won't screw anything up will it?
Edit 1: just tried it and got this
[root@ra /home/bran]# mdadm --add /dev/md127 /dev/sdf2
mdadm: /dev/sdf2 not large enough to join array
[root@ra /home/bran]# fdisk -l /dev/sdf
Disk /dev/sdf: 2.7 TiB, 3000559428096 bytes, 5860467633 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 93F9EF48-998D-4EF9-B5B7-936D4D3C7030
Device Start End Size Type
/dev/sdf1 41945088 46139375 2G Linux RAID
/dev/sdf2 47187968 5860467599 2.7T Linux RAID
/dev/sdf3 46139392 47187951 512M Linux RAID
/dev/sdf4 2048 20973559 10G Linux RAID
/dev/sdf5 20973568 41945071 10G Linux RAID
Last edited by brando56894 (2014-04-28 00:47:29)

Sorry I numbered them to show the flow of information, this was also just a place for me to store info as I worked through it. I managed to get it to work by creating a partition that takes up the whole drive and is actually 22 GB larger than all the other drives (since I found out that the had root, swap and home partitions that are no longer needed).
I should be able to resize the other partitions without a problem, correct? They're EXT4. Should I unmount the raid array and do them individually, remount the array, let it sync and do the next? Or just unmount the array, resize all of them, mount it and let it sync?

Udev/dmraid not picking up all partitions of a fake RAID setup! [EDIT]

Hey all. I've been having a problem with my RAID setup in Arch. At first Arch wasn't picking up a partition on one of my arrays, (a single large NTFS partition on a 2TB array between two 1TB drives) but after re-creating the RAID array in the Intel Storage Manager I have a different problem. Arch now find the single large partition, but now /dev/mapper isn't populated with the other two partitions on the other array that my operating systems are on (Arch and Windows), when it used to just fine! The only thing I changed was re-creating the partition table on the other array, so I don't know what's going on.
Upon trying to boot, GRUB comes back with the error described on the wiki: https://wiki.archlinux.org/index.php/In … oot_device
However I can't boot into the fallback image either! This means that I can't apply the fix as described in the wiki.
I'm starting to think there is a limitation in Arch where it can only handle a certain number of mapper devices (seems to be 3), or maybe it only detects the partitions on the first detected array? Now that I recreated the partition table on the larger array, it seems like that's the array that's detected first in both a GParted live session and Arch. But in a live GParted session, /dev/mapper was fully populated with all of my disks and partitions... so why is it that Arch can only find the partitions on one of the RAID arrays?
If you guys need any additional information just let me know... I really want to get my Arch setup up and working so I don't have to use Windows all that often (only games that don't work well in Wine).
EDIT: Changed post and title to reflect new problem after recreating the 2TB array
Last edited by pad76 (2011-08-11 13:15:36)

Does anyone know if I can damage my arch install by using mkinitcpio through a Debian live-cd? I'm going to try and use one to remake my initrd by chrooting using this guide: https://wiki.archlinux.org/index.php/In … oot_device
Basically the commands I'm looking to execute would be this:
# mount /dev/mapper/isw_ArchRaidPartition /mnt/
# mount -o bind /dev /mnt/dev
# mount -t proc none /mnt/proc
# mount -t sysfs none /mnt/sys
# chroot /mnt /bin/bash
(edit mkinitcpio.conf according to wiki, inserting the "sleep" hook)
# mkinitcpio -p 3.0-arch
So my question is would using the commands from a debian live distro work? I have to use debain since arch live-installs don't detect my arch raid partition, like how I described above. I also can't boot into fallback.

Udev/dmraid not picking up all partitions of a fake RAID setup!

Hey all. I've been having a problem with my RAID setup in Arch. At first Arch wasn't picking up a partition on one of my arrays, (a single large NTFS partition on a 2TB array between two 1TB drives) but after re-creating the RAID array in the Intel Storage Manager I have a different problem. Arch now find the single large partition, but now /dev/mapper isn't populated with the other two partitions on the other array that my operating systems are on (Arch and Windows), when it used to just fine! The only thing I changed was re-creating the partition table on the other array, so I don't know what's going on.
Upon trying to boot, GRUB comes back with the error described on the wiki: https://wiki.archlinux.org/index.php/In … oot_device
However I can't boot into the fallback image either! This means that I can't apply the fix as described in the wiki.
I'm starting to think there is a limitation in Arch where it can only handle a certain number of mapper devices (seems to be 3), or maybe it only detects the partitions on the first detected array? Now that I recreated the partition table on the larger array, it seems like that's the array that's detected first in both a GParted live session and Arch. But in a live GParted session, /dev/mapper was fully populated with all of my disks and partitions... so why is it that Arch can only find the partitions on one of the RAID arrays?
If you guys need any additional information just let me know... I really want to get my Arch setup up and working so I don't have to use Windows all that often (only games that don't work well in Wine).

Please do not crosspost. Follow forum rules.
https://bbs.archlinux.org/viewtopic.php?id=124247
Closing..

Software raid 1 drive(s) failed

Curious on what to do with a RAID 1 Drive (s) failure? I've searched the community and cannot find similar issue/answers.
Configuration:
One 1TB OS & App Drive is fine
Two 3TB RAID 1 Drives for Video scratch are fine
Two 2TB RAID 1 Data Drives are my issue
I'm using the software raid in OSX and it shows "2TB Data Drive/Mirrored Offline"
Both drives have "Failed" next to them
I have backup this Data Drive in Time Machine and a recent full back up to a single drive that is off site. I believe I have a good back up strategy with Time Machine and offsite back ups via Voyager S3. I guess we'll find out!
My question is how do I find out if it's a HW issue or SW issue with this configuration ? And then how to go about recovering them?
Initially when I looked in Disk Utility it appeared that only one of the 2TB drives had "Failed" next to it but now after a reboot "Failed" is next to both drives.
My initial hope was that one of the drives had failed and I'd be able to just replace that drive and the RAID System would rebuild from the other drive.
Any assistance would be appreciated.
Thanks

TommyH wrote:
My initial hope was that one of the drives had failed and I'd be able to just replace that drive and the RAID System would rebuild from the other drive.
RAID 1 just copies the same data to two (or more) drives at the same time, it's only for mission critical data loss requirements where a drive failure during writing would be catastrophic. Like taking purchasing orders or getting a phone call from ET for example.
RAID 0 is dangerous as the data path is separated to how many drives in the RAID 0 set, one drive glitches and all data is lost. But provides insane speeds.
RAID 5 is a much more reliable, it combines many drives (4 or more for more speed) splitting the data path but also has redundancy factor that if a drive dies it can be replaced and the data is recovered from the other drives. Usually a RAID 5 is in a external enclosure with it's own cooling and hardware controllers, not software based RAID where your CPU is being overloaded.
There are other forms of RAID some combinations like RAID 1+0, RAID 6, 10 and so forth, you can find out more about the more eclectic RAID types online.
RAID 5 is more ideally suited to video requirements for data storage, with perhaps a RAID 0 as a scratch disk or a RAID 0 + 1 (the RAID 0 is mirrored to another RAID 0) if your going to take a while working on it that increases the potential of failure.
Once the work is completed, it's sent to the RAID 5 where it's safe with it's redundancy and speed.
http://eshop.macsales.com/shop/hard-drives/RAID/Desktop
The thing to remmeber with the failed RAID 1 Data drive is the data is still on the drive, even though it failed and perhaps things are messed up a little on it on the directory. All the drive needs is to be told it's not part of a RAID 1 anymore, that it's a normal drive, a simple fix, but I don't know how to go about it.
You have two drives and two chances to recover the data off off, simply disconnect one data drive and reboot, see if it will mount and or you can repair the drive in Disk Utility.
If not pull one drive out and stick another blank one in there and download Data Rescue and simply recover the files to the new blank drive. DR works by simply reading the files themselve, not the file struture or anything else.
Software RAID is unreliable, it depends upon the CPU. Opt to get a external RAID where it's based in hardware instead. Use eSATA if all possible.
Also consider using backup software, like Carbon Copy Cloner which can be scheduled to make a backup of your data during the middle of the night. This way if something happens to either your boot drive or a data drive, the clone won't immediately copy the issue to the other drive like a RAID 1 does.
Also Carbon Copy Cloner makes "hold option" bootable OS X boot drive clones, which TimeMachine doesn't.
Also TM kicks in what, like once a hour? It's likely what caused your issue, CCC will work when you schedule it. TM is for consumers, not video pro's like yourself.
If you need even heavier iron as a external RAID setup and more expertise, then see these guys
http://www.macgurus.com/

Unable to create partition after RAID setup failure

SL - Tried to create RAID 1 with two external 250G drives. The RAID setup failed indicating improper format pair. So....I attempted to re-create the partition on one of the drives with proper settings.
It will not partition at all. It returns a POSIX error: unable to allocate memory.
I've tried the following:
Using startup disk
Partitioning using WindowsXP (which worked....only for Windows)
Tried erasing
Tried to partition with each partition type.
Nothing works! However, when I restart SL, it pops open a window indicating the drive needs to be 'initialized'. I click 'initialize' button, but that doesn't help.

Do the following:
Extended Hard Drive Preparation
1. Open Disk Utility in your Utilities folder. If you need to reformat your startup volume, then you must boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger or Leopard.)
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID (for Intel Macs) or APM (for PPC Macs) then click on the OK button. Click on the Partition button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
Are you trying to create a RAID using partitions on hard drives or using the entire drive?

Software RAID setup by partition or by drive?

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