[HOWTO] How to increase raid rebuild speed

[ibob]

Transfering while the raid is building/rebuilding will be very slow.

I didn't transfer while the raid was building. I tried to transfer a file after the raid was build with 3 drives. (2+3+4).
When that showed transfer time about an hour, I cancelled the transfer, rebooted the NAS and started expanding the raid by adding Drive 1 to the raid.

What would be the 'normal' write speed from a computer to the NAS using Samba via a direct ethernet cable after the raid has been build?

[Don]

Not sure but the 409 is a slow device. It only has a 500mhz Marvel processor.

[Tarrant1701]

My rebuilt RAID5 on a TS-509 has about the same transfer speeds as before the capacity upgrade. Across Gigabit ethernet, getting about 60-70 MB/sec for large file transfers.

[ibob]

Update: This morning my raid was finished building and I transferred a 4.7 GB file in less than 8 minutes.

So now Im happy

Thanks

[taylortap]

I've noticed that not only will this increase the RAID rebuild speed but has also increased my network thoroughput. I set my min at 100000 and everything is hauling ** now!!

Thanks OP for the information.

[Mike44]

Big thanks for this info, helped massively on a 6x3TB raid five sync. Was getting 65mb/s on my 859Pro+

Mike

[onlyalex]

Thanks for this Don

Expanding my array, adding 2x 2000gig drives would take around 48 hours.
I put the min value to 80000, running the cpu on 30% stable. The expansion was finished after 20 hours.

The % in the webpage is not to be trusted, atleast not for me. Using the "cat /proc/mdstat" command will show different numbers. And those where the accurate one's...
Best regards

[homie_g]

I have a qnap ts-639 pro, i changed the min to 100000 (5 zeroes). i ran

Code: Select all

cat /proc/sys/dev/raid/speed_limit_min

to confirm. however when i run

Code: Select all

 cat /proc/mdstat

i get speeds of around 20000 (4 zeroes) and about 1600 min remaining. i tried 80000(4 zeroes),40000 (4 zeroes) before i tried 100000 but it is all the same.

cpu usage is between 25-80%. i would say average around 50%.

am i doing something wrong? maybe this is just the HDs bottle neck? (4x wd 20eads with TLER On and is currently expanding to include 2x hd204ui samsungs (patched)) im on raid 5 and i am just expanding the array

is there anything i should do or should i just leave it?


I guess by the time I figure this out it probably would have finished. 1600 min is about 26 hours. regardless, your help is appreciated.

Thanks for this Don

The % in the webpage is not to be trusted, atleast not for me. Using the "cat /proc/mdstat" command will show different numbers. And those where the accurate one's...
Best regards

thanks for the tip. they are different.

thanks to the OP too! very helpful!
________

update: checked this morning and the speed as at 43000! so good stuff! thanks again!
I

[nnsqnap]

I'm in the process of swapping out my five Seagate 1.5TB drives (541AS) with five Hitachi 3.0TB drives (3254S) on my TS-509 Pro and I'm pretty sure I'm up against an I/O limitation or a drive limitation as the CPU is not even above 50%. I'll check the drive specs to be sure, but no matter what I crank the minimum value up to, I'm peaking at speed=36498K/sec on the RAID 5 rebuild, so it is going to be about ten and a half hours per-drive. That's way longer in a vulnerable state than I care for...

[Coume]

Thanks for the tip.

How can you make the change permanent even after reboot and/or firmware update?

Thanks

[Don]

Put the commands in your autorun.sh.

[AlanInMadrid]

Just to say that I am currently replacing the disks on my TS-419P+ It currently has 3* Samsung 500GB 7k disks and is rebuilding the array after changing one disk to a Hitachi 1.5TB 7k disk.

I was going to try this setting to speed things up, but the processor is bouncing along at pretty much 100%, with about 80% for md0_raid5 and 20% for the resync process, so I didn't change it (FW: 3.5.0) After 30 minutes, it's done 20%. The min limit is 5000, max is 200000. /proc/mdstat says: speed=62886K/sec

Does this setting only change rebuilding the RAID, or the expansion of the RAID, or both? Could it be that the newer FW already maximises the rebuild if there is I/O or processor to spare?

[remymartin]

I am a nob to the QNAP group, but not to RAID. However regarding Linux, I am a total noob and would like some help. I have the TS-212, but I see no reference to it in this thread. Is it not possible to perform this process with this unit?

[Don]

Sure it is. Just follow the directions. Not sure how much you will gain on a 212. CPU is probably maxed out during a rebuild already.

[trueimage]

does this tip apply to a TS-439 Pro II?

I'm rebuilding drive 1 right now for an expansion and it is painfully slow.

Rebuilding... (2%) - 01:29:11