RAID5 - best mode for this application?

[Maverick2002]

My company is going to be putting together a 5TB (expandable to 10TB) data storage unit (debating between a NAS and DIY) in RAID5. This seems like the best mode based on redundancy, performance, and available storage capacity per $. Everything seems to check out, except when I came across this: http://www.storagereview.com/g...pts/perfReadWrite.html

Which mentions that random write performance on RAID5 take a big hit. How often are random writes created when working with semi/large chunks of data? (not sure the best way to ask that question)

It's going to be used to read/write analysis data and high speed video footage. It's not a video capturing machine - just a very large capacity "server".

 

[Blain]

* The main priority of a business NAS should be data protection.
* High quality, high capacity, high performance backup is going to cost real money.
* If large media files are constantly being manipulated, maybe your company needs a high performance server, rather than a simple NAS.

 

[Maverick2002]

We're considering building our own. It's actually for a client. We're ok with a 1.5TB NAS (+ other backups) for now. This is going to be kind of the same thing but with much higher capacity. It's not really meant as a production machine, but rather a data storage system, so performance should be good but doesn't have to be anywhere near the level of a high end production machine.

 

[Maverick2002]

Another noob question I can't find the answer to. Once a RAID5 array is built and has data on it, can you add another drive to it to expand the storage capacity (and slowly rebuild the array obviously)?

 

[Fullmetal Chocobo]

Originally posted by: Maverick2002
Another noob question I can't find the answer to. Once a RAID5 array is built and has data on it, can you add another drive to it to expand the storage capacity (and slowly rebuild the array obviously)?

Yes, if the controller supports online expansion. This is completely dependent upon the controller.

 

[RebateMonger]

Here's a completely different option, which, given your circumstances, I'd prefer:

Consider creating arrays and volumes no larger than 2 TB each. Repair or recovery of a 10 TB array/volume is going to take a LONG time. Same thing for backup of a single 10 TB volume. And, of course, if you are using Windows, you can keep using NTFS if you stay under 2 TB volumes.

If you need redundancy and if SATA drives are OK with you, consider creating RAID 1 arrays using 2 TB drives. Since these are only file shares, any extra read speed from RAID 5 will be likely be lost during the network transfers (unless you have a 10 GB network). By avoiding RAID 5, you get around RAID 5's long rebuild times and the need to buy several new drives at a time to take advantage of newer, larger disks. If you go with a single RAID 5 array, you'll have to replace the entire bank of disks to take advantage of newer, larger, disks, and will have to rebuild the entire array each time.

If you do need maximum read and write speed, you can also consider RAID 10, which is a combination of striping and mirroring. But it'll require that you replace four disks at a time to create a larger array when larger disks are released.

 

[Maverick2002]

This is kind of a one-time solution from what I understand, I was just wondering about expandability. Regarding NTFS, can I not create a <2TB array/volume in Windows?

This is what I just found:

"Actually, it depends on implementations. Theoretical limits are unimaginable today, but in a few decades they can easily become usual, we've seen that kind of jokes before. Currently, as implemented in Windows XP Professional, with 64 KB clusters we can create volumes as large as 256 Terabytes. If we use the default 4 KB clusters, the resulting maximum volume will be around 16 Terabytes. The limit for bootable partitions is around 2 Terabytes, but it can be extended."

 

[Maverick2002]

Can anyone answer this? Do you have to use a file system other than NTFS if you want a RAIDed NAS that's over 2TB in size?

 

[Madwand1]

Originally posted by: Maverick2002
Can anyone answer this? Do you have to use a file system other than NTFS if you want a RAIDed NAS that's over 2TB in size?

No, but you need to have an OS which is newer than XP-32. E.g. XP-64, 2003 SP1 (32 or 64), Vista (32 or 64), 2008, etc., and within that construct the file system under GPT.

http://www.microsoft.com/whdc/...e/storage/LUN_SP1.mspx

http://www.microsoft.com/whdc/...e/storage/GPT_FAQ.mspx

 

[Maverick2002]

Thanks! So based on those 2 articles, would a standard install of XP64 work fine with that array? In other words, nothing special has to be done, or does it?

Also, this is probably silly, but can other 32bit operating systems access this RAID array (.e.g. over 2TB drive) as a mapped network drive for instance?

 

[Madwand1]

Originally posted by: Maverick2002
So based on those 2 articles, would a standard install of XP64 work fine with that array? In other words, nothing special has to be done, or does it?

You can't boot off the array, so you'd have to install the OS on a separate drive / array, but it's also best practice to keep the storage separate from the OS. Other than that -- just select GPT in Disk Manager before partitioning/formatting the array.

Originally posted by: Maverick2002
can other 32bit operating systems access this RAID array (.e.g. over 2TB drive) as a mapped network drive for instance?

32-bit OS's can access the shared drive as an ordinary share, regardless of size / GPT, etc., because the server OS handles that part.

 

[Maverick2002]

Ok, that's what I needed to know. OS will probably be on a separate drive. But I guess my question then becomes: can I create an array over 2TB in a 32bit OS even if I'm booting of a separate, smaller drive. Or does the array have to be created via a 64bit OS? (not sure if I'm saying this right)

 

[Madwand1]

Originally posted by: Maverick2002
Ok, that's what I needed to know. OS will probably be on a separate drive. But I guess my question then becomes: can I create an array over 2TB in a 32bit OS even if I'm booting of a separate, smaller drive. Or does the array have to be created via a 64bit OS? (not sure if I'm saying this right)

It's not 32-bit vs. 64-bit, it's the generation of the OS. XP-64 is of the 2003 generation, which is after XP-32. 32-bit 2003 also has support for GPT. On the server itself, you have to have an OS after XP-32 in order to create or access the GPT >2TB array.

 

[Maverick2002]

Ok, thanks for the info, MUCH appreciated!

 

[Maverick2002]

Originally posted by: Madwand1

32-bit OS's can access the shared drive as an ordinary share, regardless of size / GPT, etc., because the server OS handles that part.

Actually, are you sure about this?

http://www.microsoft.com/whdc/...e/storage/GPT_FAQ.mspx


14. Can the 32-bit version of Windows XP read, write, and boot from GPT disks?
No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.

15. Can the 32-bit versions of Windows Server 2003 read, write, and boot from GPT disks?
All versions of Windows 2003 since Server Pack 1 can use GPT partitioned disks for data. Booting is only supported for Itanium-based systems.

16. Can Windows Vista and Windows Server 2008 read, write, and boot from GPT disks?
Yes, all versions can use GPT partitioned disks for data. Booting is only supported for EFI-based systems.

17. Can Windows 2000, Windows NT 4, or Windows 95/98 read, write, and boot from GPT?
No. Again, legacy software will see only the Protective MBR.



It says these operating systems can read/write to GPT ... does this somehow not affect shared drives (i.e. it only applies to physically mounted drives)??


EDIT: nevermind, called one of our other techs. Looks like a share is independent of the OS.