Dell R420 Strange HD behaviour

[Jawloms]

Since starting here I commented to one of my colleagues that one of the servers seemed a bit slow. He said it had been like that since we got it which I was a little surprised about as we've had it a year! It's a Dell PowerEdge R420 with a S110 RAID controller (software, on the motherboard) and 3x 2TB 7200rpm disks. They were setup in a RAID 5 config. Disk activity seemed slow to me, and at one point one I tried to restore a VM to it, it pretty much stopped the server working at all. I copied a large file from it's E drive to the same folder on the E drive and it copied at around 6MB/s. We have an identical server which copies at around 70MB/s. Over the summer I took the opportunity to move the couple of VMs off it and wipe it. I deleted the RAID config, recreated it and re-setup a RAID5 with one virtual disk of 3.7TB. I also upgraded the existing 32GB of RAM to 64GB. I installed Windows Server 2012 R2 with all the Windows updates. Speed issue remained. I contacted Dell. With them I have made sure that ALL firmware is on the latest versions and that made no difference, and we have run all their diagnostics tests and all pass. They have had the motherboard replaced, no difference. Since then I have tried removing the riser cards, the additional 4 port NIC, and the iDRAC card to see if that made a difference and it didn’t. I also tried removing the memory which came with the server originally and just leaving in the 2x 16GB memory modules which I recently purchased and it was still slow. I have also updated all the firmware on the replacement motherboard to the latest version. This morning I deleted the RAID 5 configuration completely and re-installed Server 2012 R2 on to just one of the disks, then set the other two disks up as standalone disks with one partition on each. I then copied a large (8GB) file (we’ll call it “xxx”) from the network to one of the local disks and it transferred at 150meg/sec, so I copied “xxx” locally from D: to F: and it copied at 1.5gig/sec - slightly better than the 6MB/s I was getting. After a reboot, copying “xxx” from D: to F: again copies at 20meg/sec. Copying a new file (“yyy”) on to D: copies at 150meg/sec and if I then copy “yyy” from D: to F: it will copy at 1.5gig/sec but the “xxx” from D: to F: goes at 20meg/sec. A reboot again will then make “yyy” copy at 20meg/sec. Copying another new file (“zzz”) on to D: copies at 150meg/sec and if I then copy “zzz” from D: to F: it will copy at 1.5gig/sec but the “xxx” or “yyy” files from D: to F: goes at 20meg/sec. A reboot again will then make “zzz” copy at 20meg/sec. And so on and so on…….

 

I’ve done a lot of Googling and found a lot of other people reporting very poor speed with RAID5 with the S110, but presumably as I’ve deleted the RAID and not set up any virtual disks, I’m not using the S110 now anyway? And the lag you get from RAID5 and it's parity writing won't exist as it isn't RAID5 anymore. The other identical server I have unfortunately is in constant use so I can't do too many tests on it, and I certainly can't reboot it whenever I fancy.

 

Anyone.....? What is going on? Dell have escalated the call to the software team and I am awaiting their response.

 

Stuart

[NB9457]

Poor performance from PERC S110 in RAID 5 - PowerEdge HDD/SCSI/RAID Forum - Servers - Dell Community

 

Software RAID sounds like the problem here. Seems the best option would be to run them as they are now (which obviously isn't a great idea) or buy a physical RAID controller. I've had issues similar in the past, don't think I'd use software RAID again on a server, too much demand it seems.

[Jawloms]

I did wonder about running the disks as they are currently and using DFS to replicate the data, at least I have some sort of redundancy then.

 

What about the copying at 1.5gig/sec until a reboot when it reverts to 20mb/sec? Is that something caching something somewhere?