Choosing a RAID Configuration

moguy78 · 10-16-2009, 11:22 PM

I am wanting to set up a home file server using a RAID
configuration for data protection, but I can't find the
method that I'd like to use.

What I'd like to do is use my (6) 500 GB HD's and create
(3) 500 GB RAID 1 array drives, then fix it where they're
all viewed as 1 logical drive (I think it's called spanning
the drives). The closest method I could find was the RAID 1+0
(or the RAID 10), but I don't really want the worry of them
being striped. I just want it as if it's one HD after the
other (where the last data block on one drive is directly
followed by the first block on the next drive).

Does anyone have any ideas? Any help will be appreciated.

**raptor_pa** · 10-17-2009, 06:28 AM

I don't know if you will be able to do that all hardware. What OS version are you running? You could create the three raid1 volumes in hardware, then use windows (if you are running a version that provides software raid to build the simple spanned volume. This would require another single drive to host the operating system. I have seen controllers that will support JBOD in a spanned volume, but not sure they will use raid1 volumes as the elements in the volume. Just curious why you want to avoid the stripe set?

Dogg · 10-17-2009, 09:25 AM

Depending on your RAID chipset, you could simply create a RAID 5 array using only 4 of the drives. The storage space would be the same, and you have security. If any one of the drives fails, you simply replace it and the array is rebuilt from the data on the other 3 drives.

moguy78 · 10-19-2009, 10:59 AM

I haven't really thought about Striping much because I've had trouble
losing a lot of files with it in the past on other systems when a drive
would give out (of course I didn't have each of the drives mirrored
in those instances.)
I guess I really don't know as much about spanning. If one drive gives
out, the data on the other drives is still saved, correct?

I've thought about RAID 5, but I don't completely understand how
it works. I know RAID 0 stripes the data across 2 disks making it
look as 1, and I know RAID 1 mirrors the data onto both of the drives
(though you see only one of them.) What and how exactly does it work?

**raptor_pa** · 10-19-2009, 11:24 AM

The data is saved, but the MFT is stored on the first drive, so if the first drive fails, then the pointers tot he rest of the data and filenames is lost. Also if one of the middle drives fails, the block count is incorrect, Logical blocks include the middle drives and go from start to end, as an example, numbers are completely made up, your aray consists of 10,000 logical blocks, 2000 on each of 5 drives, and the MFT references block 6000 for a start, and blocks 2000 - 3999 are missing, then it may not be able to find the files on following drives. RAID is not a substitute for backups. It is designed to allow the system to continue to function in the event of physical drive failure. Logical problems with the file system are not protected. Unless you really need large capacity of a spanned volume ( major email archives, databases etc, then your safest bet would be to use single drives, and use DFS under windows - or the comparable under your OS - server to map to differng share points, but it would look to the user like it was shares on one logical location. Raid5 creates a parity stripe as well as the data stripes. The parity stripe can be used to rebuild the data for the other drives if one of them goes missing. Each drive contains enough parity information to rebuild each of the other drives. The scrifice is the loss of the storage capacity of one drive in the array. So if you used 5 1TB drives, you would have 4TB of storage. Raid1 simply writes all data to both drives, creatinga mirror of each other. 2 - 1TB drives = 1 TB of storage, but a complete volume. The failed drive in either can be replaced and the array will rebuild the missing drive on the new one.
Unless you use one of the redundant types of RAID there is no real advantage ( and probably more downsides) to using Raid0 or spanned volumes.

moguy78 · 10-20-2009, 08:06 PM

So out of all of the options, Raid 1 and Raid 10 are probably the best
because the data on each of the drives is mirrored. Besides just having
3 mirrored sets being striped and appear as one drive, Is Raid 10 much
different than Raid 1? Is there that much of an increase in the READ
speed since the 3 sets are striped than it would be just reading straight
from one standard RAID 1 drive?

As I said in my original question, I would like to have my drives mirrored
for data protection, and I do also have a USB drive that I will use to
back up everything onto once a week.

**raptor_pa** · 10-20-2009, 08:20 PM

Read speed is probably some SLIGHT improvement, you probably aren't going to notice a lot connected across the network due to the network speeds.

moguy78 · 10-25-2009, 12:51 PM

If there's not that much of a difference, I'll most likely just use raid 1. As long as I
have a good solution with the least chance of losing anything, that's good enough
for me. Thanks for all the help everyone.

10-16-2009, 11:22 PM	#1 (permalink)
moguy78 Registered User Join Date: Mar 2009 Posts: 4 OS: Windows XP sp3	Choosing a RAID Configuration I am wanting to set up a home file server using a RAID configuration for data protection, but I can't find the method that I'd like to use. What I'd like to do is use my (6) 500 GB HD's and create (3) 500 GB RAID 1 array drives, then fix it where they're all viewed as 1 logical drive (I think it's called spanning the drives). The closest method I could find was the RAID 1+0 (or the RAID 10), but I don't really want the worry of them being striped. I just want it as if it's one HD after the other (where the last data block on one drive is directly followed by the first block on the next drive). Does anyone have any ideas? Any help will be appreciated.

10-17-2009, 06:28 AM	#2 (permalink)
raptor_pa Mod Hardware Team Join Date: Dec 2008 Location: Central PA Posts: 4,798 OS: XP	Re: Choosing a RAID Configuration I don't know if you will be able to do that all hardware. What OS version are you running? You could create the three raid1 volumes in hardware, then use windows (if you are running a version that provides software raid to build the simple spanned volume. This would require another single drive to host the operating system. I have seen controllers that will support JBOD in a spanned volume, but not sure they will use raid1 volumes as the elements in the volume. Just curious why you want to avoid the stripe set? __________________

10-17-2009, 09:25 AM	#3 (permalink)
Dogg Tech Hardware Team Join Date: Apr 2009 Location: St Louis, MO Posts: 1,973 OS: XP sp3	Re: Choosing a RAID Configuration Depending on your RAID chipset, you could simply create a RAID 5 array using only 4 of the drives. The storage space would be the same, and you have security. If any one of the drives fails, you simply replace it and the array is rebuilt from the data on the other 3 drives. __________________ Google is your friend !

10-19-2009, 10:59 AM	#4 (permalink)
moguy78 Registered User Join Date: Mar 2009 Posts: 4 OS: Windows XP sp3	Re: Choosing a RAID Configuration I haven't really thought about Striping much because I've had trouble losing a lot of files with it in the past on other systems when a drive would give out (of course I didn't have each of the drives mirrored in those instances.) I guess I really don't know as much about spanning. If one drive gives out, the data on the other drives is still saved, correct? I've thought about RAID 5, but I don't completely understand how it works. I know RAID 0 stripes the data across 2 disks making it look as 1, and I know RAID 1 mirrors the data onto both of the drives (though you see only one of them.) What and how exactly does it work?

10-19-2009, 11:24 AM	#5 (permalink)
raptor_pa Mod Hardware Team Join Date: Dec 2008 Location: Central PA Posts: 4,798 OS: XP	Re: Choosing a RAID Configuration The data is saved, but the MFT is stored on the first drive, so if the first drive fails, then the pointers tot he rest of the data and filenames is lost. Also if one of the middle drives fails, the block count is incorrect, Logical blocks include the middle drives and go from start to end, as an example, numbers are completely made up, your aray consists of 10,000 logical blocks, 2000 on each of 5 drives, and the MFT references block 6000 for a start, and blocks 2000 - 3999 are missing, then it may not be able to find the files on following drives. RAID is not a substitute for backups. It is designed to allow the system to continue to function in the event of physical drive failure. Logical problems with the file system are not protected. Unless you really need large capacity of a spanned volume ( major email archives, databases etc, then your safest bet would be to use single drives, and use DFS under windows - or the comparable under your OS - server to map to differng share points, but it would look to the user like it was shares on one logical location. Raid5 creates a parity stripe as well as the data stripes. The parity stripe can be used to rebuild the data for the other drives if one of them goes missing. Each drive contains enough parity information to rebuild each of the other drives. The scrifice is the loss of the storage capacity of one drive in the array. So if you used 5 1TB drives, you would have 4TB of storage. Raid1 simply writes all data to both drives, creatinga mirror of each other. 2 - 1TB drives = 1 TB of storage, but a complete volume. The failed drive in either can be replaced and the array will rebuild the missing drive on the new one. Unless you use one of the redundant types of RAID there is no real advantage ( and probably more downsides) to using Raid0 or spanned volumes. __________________

10-20-2009, 08:06 PM	#6 (permalink)
moguy78 Registered User Join Date: Mar 2009 Posts: 4 OS: Windows XP sp3	Re: Choosing a RAID Configuration So out of all of the options, Raid 1 and Raid 10 are probably the best because the data on each of the drives is mirrored. Besides just having 3 mirrored sets being striped and appear as one drive, Is Raid 10 much different than Raid 1? Is there that much of an increase in the READ speed since the 3 sets are striped than it would be just reading straight from one standard RAID 1 drive? As I said in my original question, I would like to have my drives mirrored for data protection, and I do also have a USB drive that I will use to back up everything onto once a week.

10-20-2009, 08:20 PM	#7 (permalink)
raptor_pa Mod Hardware Team Join Date: Dec 2008 Location: Central PA Posts: 4,798 OS: XP	Re: Choosing a RAID Configuration Read speed is probably some SLIGHT improvement, you probably aren't going to notice a lot connected across the network due to the network speeds. __________________

10-25-2009, 12:51 PM	#8 (permalink)
moguy78 Registered User Join Date: Mar 2009 Posts: 4 OS: Windows XP sp3	Re: Choosing a RAID Configuration If there's not that much of a difference, I'll most likely just use raid 1. As long as I have a good solution with the least chance of losing anything, that's good enough for me. Thanks for all the help everyone.