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Will it work to replace 1.5TB disk with 2TB disk in Intel RAID 1 Array?

donander asked
Last Modified: 2016-12-08
I have a Dell XPS 8100 machine running Windows 7. I purchased it with a RAID 1 configuration. The RAID controller is the Intel Rapid Storage Technology controller. Size of the array is 1.5TB. It has two Seagate st31500341as 1.5 TB SATA drives.

Today I saw a message that one of the drives has failed. As recommended by the help section of the controller I clicked on the failed drive and selected "set to normal". It is rebuilding the array now and is at 9% complete. I think it will not say if it was successful until it gets to 100% but regardless of that I want to purchase a spare drive to replace the one that failed. On Amazon a 1.5TB drive is $93 with free shipping from Databug but I don't know how long that will take to get to me. If I change it to 2TB I can get that with the standard 2-day Prime shipping and get it Wednesday or pay $3.99 to get it Tuesday. The 2TB drive will be fulfilled by Amazon and trackable.

My question is, if I replace the failed 1.5TB drive with a 2TB version of that drive will the Intel Rapid Storage Technology controller be ok with that? I know that the array will still only be 1.5TB but I want to get the replacement drive as fast as possible. I know that you can mix sizes for RAID 5 and the resultant array is determined by the size of the smallest drive so I think this should work but just wanted to check.
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Most Valuable Expert 2015

That controller is only a fakeRAID controller. You should NEVER EVER use the RAID functions of such a fakeRAID controller, as it is highly unreliable and performs poorly. You should rather disable RAID on the controller and set it to AHCI or SATA mode (or whatever it is called there). Then use your OS's built-in software RAID, which is far more reliable and also performs much better, as it does read balancing (it reads data from both disks simultaneously, which speeds up the reads), which the RAID of the controller can't.

As your array is broken anyway you should take this chance to reconfigure the system for software RAID.
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rindi: While I appreciate that you are trying to educate me about fake RAID, this computer came configured this way from Dell. I just ordered it with a 1.5 TB RAID 1 configuration. Functionally for me, my array is not really broken, only degraded because of the one failed drive. My goal is to replace the failed drive as soon as possible and get on with my life. I don't have time to embark on a project to reconfigure the type of RAID I'm using on this computer. Perhaps sometime in the future I will do this or build a computer this way. If I did so I'd use a hardware RAID controller.

dlethe: The 1.5TB drive seems to be 512 bytes for sure as shown in the table here:

The 2TB drive I can get with Prime shipping does mention 4K technology:

It does have this note below the table of specs:
2-Seagate ships this drive in both 4K- and 512-byte sectors. SmartAlign technology is included on 4K sector drives. Both drives are functionally and physically equivalent.

This seems to indicate one could use it with a RAID system that expects 512 byte sectors but I think I'm going to go the safe route and by the 512 byte sector drive.

Top Expert 2010

Then you can't use the 4Kb drive.  The Smartalign does NOT work in this config.  You must buy a 512 byte sectored drive.


Yup, ordered it today.
Natty GregIn Theory (IT)

Absolutely not, however what was mention software raid is better, raid arrays always use the same size, and type for reliability
Top Expert 2010

RAID arrays do not always use the same size/type for reliability.  Go to dell and prove it yourself.  They support mixed arrays as long as you get models of drives they qualify.  They have to, drives burn out and they stop making older models at times.   Dell doesn't drop support on you if you don't replace all the disks with the same model.

Also Solaris software RAID is designed to support non-matching disks.  You can have a RAID array that combines 1TB and 2TB drives, along with SCSI and SATA drives all in the same array if you want to.   Heck, you can even throw in a few USB sticks if you want and create a highly reliable array if you play by some rules.


The response by dlethe provided the information I was seeking.

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