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I have run disk i/o test on my cent 6.4 OS, Apache, RAID-10 Disk VPS. Every time my file copy speed bellow the 55MB/s. Is it bellow the optimum level or normal?

root@host [~]# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 21.1441 s, 50.8 MB/s
root@host [~]# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 20.8749 s, 51.4 MB/s
root@host [~]# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 23.7294 s, 45.2 MB/s
root@host [~]#
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    50MB/sec is certainly far from a typical top speed, it's unlikely to make a huge impact on the typical duties of a web server or other lightly loaded VPS. Commented Aug 30, 2013 at 9:39
  • I have submitted a ticket, but they're not ready to accept this is out of performance.I think i have to mention more information or change the VPS.
    – MaxBro57
    Commented Aug 30, 2013 at 12:26

2 Answers 2

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It's poor speed. It's definitely not optimal... It may be all that's possible with the VPS provider you have and the limitations of the host's hardware, though.

Are you having a problem that actually affects your application, or are you just testing sequential I/O throughput? If the performance is not up to your standard or if it negatively impacts your application, you should contact the VPS provider and complain.

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  • After i contacted the vps company, they told me that. With a 100 Mbit/s connection this is acceptable level. Is it true or they're cheating me?
    – MaxBro57
    Commented Aug 30, 2013 at 12:20
  • With a loaded 1Gbps connection to storage, this is almost acceptable. You may want to go with a VPS with local disk storage... Unless this doesn't impact your application. For the tasks you'd use a VPS for, this storage setup may be just fine.
    – ewwhite
    Commented Aug 30, 2013 at 12:30
  • Thank you ewwhite. I think, I'm not correctly understand your statement. Could you please describe it more. You mean with 100Mb/s line this is OK or ...?
    – MaxBro57
    Commented Aug 30, 2013 at 12:35
  • 100Mbps is less than the speed you're getting.
    – ewwhite
    Commented Aug 30, 2013 at 12:42
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It depends on the underlying hardware (controllers, disks etc) and other load on the host system. For example, your same test on my RAID-10 SSD array produces wildly different results:

$ dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 2.88746 s, 372 MB/s

So if your underlying hardware is a RAID-10 of 1.44mb floppy drives, then I'd say it is outstanding performance ;)

Your test is unlikely to ever produce "optimum" performance, and if you ran it multiple times randomly over a 24 hour period, you'll likely get varying results. Some will be better and some likely worse as other workloads (ie, other VPS') make differing demands on the host server.

What it does give you an idea of your potential "real-world" performance that you will get from that provider. You need to make the call if it is sufficient for your needs or not.

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  • Thanks fukawi2. My VPS provider will not accept this is out of performance. They told me that, with a 100Mb/s connection, it's acceptable. Is it true or they misleading me?
    – MaxBro57
    Commented Aug 30, 2013 at 12:25
  • @chris If they are using iSCSI as a backend for their storage, then it's probably pretty average performance. It's spectacular performance if they're running iSCSI at 100mbps, which would be very strange. Testing my RAID-10 iSCSI SAN which is Multipathed over Gigabit copper peaks at 182.32MB/s for 64k sequential writes.
    – fukawi2
    Commented Aug 31, 2013 at 0:39

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