18 TB RAID 6 NAS rebuilding failed drive

http://louwrentius.com/blog/2009/07/20-disk-18-tb-raid-6-storage-based-on-deb...

For Nerds only. 18 TB RAID 6 NAS based on Linux software RAID. This video shows how the system starts rebuilding a drive and is reading the array at 1.1 GB/s.

I have never seen a Linux RAID array reaching 1.1 GB/s ever using regular disks. To be honest, there aren't probably many hardware RAID cards capable of delivering this performance in real life.

Now running for 2.5 years.

Category:

Science & Technology

Tags:

• Linux
• RAID
• mdadm

[TomTeneg]

only 1GB/s?

I had 550MB from four 500GB SATA Barracuda drives. However, in mdadm RAID0.

RAID6 is very CPU-intensive. Go with RAID10, suppose to have higher write rates.

I've tested it on 12 drives, in best scenario 1/2 of them (six) can die, leaving data unaffected, depending on which will be dead. In the worst - only two.

As You can see there is rebuliding rate limit (200MB/s), can be check at:

/proc/sys/dev/raid/speed_limit­_max

and

/proc/sys/dev/raid/speed_limit­_min

You can change this.

[louwrentius]

Dear TomTeneg,

1. RAID 10 : if the wrong 2 drives fail you loose all data. RAID6 doesn't have this risk.

2. What is more important for a home NAS: speed or storage capacity?

3. Your comment about rebuilding rate limiting is irrelevant as this limit is not reached.

Oh and,

"Only 1 GB/s?"

Come again?

[louwrentius]

Yes this is possible, but it will take about 20 times 5 hours = 100 hours excluding overhead. It will take weeks.

[louwrentius]

Norco rpc-4020

[louwrentius]

A rebuild takes about 5 hours, without any load.

[TylertheGeek28]

No wonder it failed there's a Apple sticker on the monitor ! lol just kidding nice setup

[Elelment5]

What system is this? IBM, HP, or Dell? That's massive!

[Jdwill1014]

hes got all his porn backed up on there 

[m4r71jn]

@TomTeneg With regards to your own private porn library it is indeed recommended to prefer the i/o of onboard raid 0 instead of the reliability and redundancy of a dedicated raid 6 setup.

[m4r71jn]

Him comparing raid 0 with raid 6 setups only in terms of speed is just plain moronic.

[m4r71jn]

@TomTeneg "RAID6 is very CPU-intensive" yeah duh... Thats why we use 500+ a pop dedicated raid controllers instead of those cheap ass fake onboard raid support you got 4 free with your consumer grade motherboard.

Go with raid 10 when you are poor and don't have the bucks to buy decent dedicated raid controllers.

[m4r71jn]

@louwrentius Bet he never reached 1gbps on his consumer grade setup with fake raid, wish he told us something we didn't already know...

[b2lee2]

About as fun as watching paint dry

[SLRist]

Looks like it's about to fall off the desk. So much for data protection...