Transfer speed - Multiple Disk Array

[Mat1926]

I enabled the reconstruct setting and now the transfer speed to the unraid system over network is almost what is expected. Now I am transferring ~23 TB of data from my 1st WD NAS appliance to the unraid system.

 

The reconstruct setting does it impose any risks at all regarding data corruption/loss?

If I started any download/upload sessions on my main desktop connected to the same network connected on the same router/switch, is there a chance of data corruption during the data transfer to the unraid? Are there any speed penalties?

 

Thnx

 

P.S. I did purchase the pro key, and was able to enable it on my system...

[JorgeB]

15 minutes ago, Mat1926 said:

The reconstruct setting does it impose any risks at all regarding data corruption/loss?

No, the only disadvantage of turbo write is that all disks spin up for writes, no difference in data integrity.

[Mat1926]

2 minutes ago, johnnie.black said:

No, the only disadvantage of turbo write is that all disks spin up for writes, no difference in data integrity.

 

thnx, what about this?

Quote

If I started any download/upload sessions on my main desktop connected to the same network connected on the same router/switch, is there a chance of data corruption during the data transfer to the unraid? Are there any speed penalties?

 

[JorgeB]

6 minutes ago, Mat1926 said:

If I started any download/upload sessions on my main desktop connected to the same network connected on the same router/switch, is there a chance of data corruption during the data transfer to the unraid?

There shouldn't be, ethernet checksums all data.

 

6 minutes ago, Mat1926 said:

Are there any speed penalties?

Probably nothing noticeable but it depends mostly on your LAN hardware.

[Mat1926]

2 minutes ago, johnnie.black said:

There shouldn't be, ethernet checksums all data.

 

Probably nothing noticeable but it depends mostly on your LAN hardware.

 

Brilliant, Thank you a lot for the help

[SSD]

You might say reconstruct mode is slightly safer. It is literally rebuilding pieces of parity with every copy. If parity were corrupted, this would put it right for the sectors occupied for the newly copied files. Normal writes would perpetuate the parity corruption.

 

(Don't want to overstate this, unRaid does an outstanding job of maintaining parity and the chances of it getting out of sync are very low and very probably point to a user error or hardware issue.)

 

Interesting thought ... If you enabled reconstruct mode on a new array before any disks were even formatted, and then did a massive copy filling the largest array disk with reconstruct mode enabled, parity would be inherently built (and any sectors that weren't, wouldn't negatively affect a drive re build and could be corrected by an ensuing parity check. ) Very interesting ...

 

(#ssdindex)

[pwm]

13 hours ago, SSD said:

You might say reconstruct mode is slightly safer. It is literally rebuilding pieces of parity with every copy. If parity were corrupted, this would put it right for the sectors occupied for the newly copied files. Normal writes would perpetuate the parity corruption.

But if a data disk on the other hand starts to produce bad data without giving a read error, then the parity will be rewritten. That's the dreaded "silent data corruption" that is the reason why newer file systems introduces checksums also for data, and why there exists software that computes external file/block checksums etc.

 

It's also an important reason why the drive industry wants to move to true 4kB sector sizes, with at the same time improves the effectiveness of the sector ECC.

 

In the end, the biggest difference with constructive write enabled is that by requiring access to every disk when writing, writes to one disk affects concurrent read-only accesses to other disks.