expected raid5 write speed on LS-QL?

[jdgordon]

   

hey all,

I deleted the initial raid array while I was playing with it (no data yet..) and after I recreated the raid5 over all 4 disks and started using it I was getting about 10MB/s write speed... is that about expected? or is that because it was doing the raid scan in the background? and if so.. what is the expected write speed?

[Dustrega]

Since the data is being written in blocks across the 4 HDDs then 10 MB/s is a nominal speed to be expecting.

[jdgordon]

   

wow, really! I was expecting/hopeing for at least 30MB/s which a single disk can do easily.. and being spread over multiple disks I would assume it could handle more (even with the parity checking)...

So, If I want faster write I should just use RAID10?

 

hmm.. it seems I may have been a bit ambiguous... is 10MB/s the expected speed for when the scan is NOT running? 

[Dustrega]

Standard data transfer speed over a gigabit network is 7 MB/s so you're above the bar at this point.  Since the NAS is not a USB device and each piece of data is wrapped in layers and layers of network packets the write speed is considerably slowed.  This is normal for most if not all network devices.

 

E: Sorry, changing the RAID may improve the write speed slightly but not drastically.  The only thing I could suggest is playing with the ethernet frame size in the Network area on the admin console.

Message Edited by Dustrega on 05-04-2009 04:22 PM

[jdgordon]

   

! good thing I got it with a 15day return policy... I cant belive 7MB/s is expected... 7 is understandable for 100mbit ethernet, I can sustain 30+MB/s across gigabit between 2 linux hosts with just boring sata disks...

its a shame because I love the size of it