NAS stand alone or PC NAS?

[cuti7399]

I'm debating whether to buy a NAS stand alone device (particularly the Dlink DNS323) and ran raid 1 or build a spare pc for raid 5. So couple of questions that I could use some help

1. Is raid 1 significantly slower?
2. Can I use the raid on the mobo if i build a pc or should I get a raid controller card?
3. is raid 5 safe for critical data or should I go with raid1?
4. If i start out with raid 1 right now, can I migrate it to raid 5 later?

Thanks all

 

[MerlinRML]

1) is raid 1 slower than what? RAID 1 typically performs just like a single disk, even though you have 2 disks. RAID 5 should have better disk performance and give you n-1 disk performance with a penalty on writes and CPU utilization for parity calculations.

2) You sure can use driver-based RAID (aka fakeraid, softraid, onboard RAID, host-based RAID) for whatever the chip supports. There are some good reasons to do so and some good reasons not to. These have been covered many times in many threads already and right now I'm not up to rehashing that argument. Basically it boils down to onboard is cheaper and when it works it usually works pretty well, but it's not as good as a hardware controller when it comes to RAID 5 and is usually harder to deal with when it breaks.

3) RAID 5 and RAID 1 are both redundant and should be safe for critical data; However, RAID is not a backup. It is a way of maintaining uptime and preventing data loss in the event of one or more disk failures. It is susceptible to any number of other forms of disaster. Once more for emphasis, RAID is not a backup.

4) Possibly. You need to make sure whichever controller you use supports RAID level migration and then you'll be fine. Otherwise, you need a buffer location to store your data while you destroy and recreate the array.

I tend to really dislike most of the consumer NAS units when a cheap P3 will more than suffice for most file-serving needs. Maybe someone else can chime in on the Dlink you're looking at.

 

[cuti7399]

thanks for the input and info merlinrml

 

[RebateMonger]

Originally posted by: cuti7399
3. is raid 5 safe for critical data or should I go with raid1?

Neither one is "safe for critical data". If your data is critical, FIRST set up an ongoing backup system. If, after setting up a backup system, you still want RAID (for either uptime or data read speed), THEN put in a redundant RAID system.

People with RAID arrays lose critical data all the time. Especially with RAID 5. But I've had my own server's RAID 1 array corrupt data too.

 

[Slowlearner]

All RAID arrays have a critical vulnerability in case of power failure they need to be shut down - so you definitely need an UPS that has 15 mins at least of standby power and has associated software that will shut down the NAS in an orderly manner. On any RAID array abruptly shut it down, it will take a very, repeat very, long time to re-build the array - that is if it does not some lose data in the process or fail completely - RAID 1 or 5 is a convenience rather than an option for backup.