I have a Dell PowerEdge R820 server which is under maintenance by other third party. There are 6 SAS (10K RPM, 6gbps) disks and they are configured as RAID 5 using PERC controller. Currently I am facing performance issue with the server. Basically it is with the disk. When I tried to write 4GB of data, it is taking 12 minutes to complete. I am using a Linux Server. Please see the output of dd command: # # time dd if=/dev/zero of=TestFile bs=4096 count=10240001024000+0 records in1024000+0 records outreal    12m 3.56suser    0m 7.94ssys 0m 0.00sI have also checked with the other Desktop made server, where RAID 5 is configured with 4 SATA (7.2K RPM) disks. It is taking only 19 seconds to write 4GB of data to the disk. I can see the clear problem of disk I/O performance issue. But the third party is denying, they are telling that, this is the normal time. But I refuse to agree with them. Can you please tell me what should be the normal time to write 4GB data to the volume configured with 6SAS (10K RPM) disks?
Disk I/O performance issue
linux;performance;io;disk;raid5
That does seem like a disk performance issue.You should get something in between 20 MB/s to 80 MB/s depending on block size I think.I found this old 10k disk comparison where you can see how different drives are performing http://techreport.com/review/5236/10k-rpm-hard-drive-comparison/7 .I also found a thread from dell forum where someone is facing same kind of issue:http://en.community.dell.com/support-forums/servers/f/906/t/19475037To answer you question: No 5-6 MB/s is not normal.