Just built a Synology DX513 NAS with 2 DS1512+ expansions.

 

The write speed to the hybrid software raid setup is amazing, 60+ MB/s.

 

How does synology achieve this, the software raid seems very very similar to unraid, which for me caps out at 24 MB/s.

They do raid, so writes go to different hdd's in parrallel, not 1 hdd as with unraid i guess.

Unraid writes can go over 24 Mbyte/sec also, i see peaks to 80 Mbyte/sec and lows of 30+ directly to the protected volume withouth cache drive even.

 

But what happens when 2 discs fail with your synology, or 1 fails, you rebuilt and during rebuilt another disc fails. All your data gone....

 

And it does not scale as cheap as unraid, even with the 2 expantions. But if money is no problem, go raid-6 and all 4 TB drives so hopefully dont have a issue soon..

How do I get my unraid right speeds up above 24?  Is it CPU dependent or disk dependent?  I run 5400rpm drives so maybe that is why they are slow?

 

The synology runs raid, and also a synology hybrid software raid, and it uses different sized drives just like unraid, and with 4+ disks it has dual hard drive failure protection.

 

I am not a fan due to the cost of the boxes, but I am wondering how they are so fast, especially when the expansion I am writing to is connecting 5 drives through a single sata cable and the wrote speed is still over 60MB/s.

place one disk in the extension and the speed might go down, though 1 hdd could do 60 Mbyte/sec also.

 

You can use the search and find some posts how unraid does a write to the protected volume. It has to do that it needs to read the parity disk, and than re-compute the parity and write that back to the parity disk, next to the data write or something like that.

Read: http://lime-technology.com/forum/index.php?topic=4390.msg40666#msg40666

 

 

So there are more I/O action involved as with a RAID-5/6 setup as you calcluate parity and devide the data into lets say 4 parts. You than write to 5 or 6 hdd's only 1/4 of the original data in parrallel.

 

How do I get my unraid right speeds up above 24?  Is it CPU dependent or disk dependent?  I run 5400rpm drives so maybe that is why they are slow?

I have 7200 rpm 3 TB and 4 TB drives and to them i see thos faster writes. These new hdd's seem much faster than the 1 TB hdd's i used before.

It is not running raid 5/6, it is running software raid of some sort, similar to unraid but faster, at least compared to my unraid box.

 

I am writing right now to the expansion filled with 5x3tb drives, writing at 62MB/s through the main synology box through a single esata cable.  I never expected those kinds of speeds to 5 drives through a single sata cable.

How do I get my unraid right speeds up above 24?  Is it CPU dependent or disk dependent?  I run 5400rpm drives so maybe that is why they are slow?

I have 7200 rpm 3 TB and 4 TB drives and to them i see thos faster writes. These new hdd's seem much faster than the 1 TB hdd's i used before.

 

Maybe I will see a speed increase one I finish upgrading my 1.5 to 3tb drives. I can hope!