Bad disk performance

[perfectid]

Hi all,

We have the following situation; a server equipped with VMware ESXi had a VM installed with CentOS/RHEL.

For security reasons this VM had to be reinstalled, however we chose to perform a side to side installation for easy-migration of data.

After setting up the new VM the disk performance was bad, the new VM had a different version of CentOS (5.4 instead of 5.3 compared to the old VM).

I figured this was due to disk interaction of both VM's, after deleting the first, the problem still occurs.

So then I thought; maybe this is a disk issue, so today I replaced the disk in order to get a quick machine again.

Due to the replacement of the disk, I had to reinstall ESXi and the VM.

Did that, but still the diskperformance is sooo bad.

Is there something i'm overseeing here?

Is the hardware faulty? (it's a DELL PowerEdge R200, with single disk, no RAID).

Any idea's, because I'm out by now

Gr, Mike

[perfectid]

Some extra info:

I also tried to install the same version that was already installed: CentOS 5.3

Still same issue...

I've tried to change the controller from LSI Parallel to LSI SAS

Still same issue...

And last but not least; i've updated the VMware host to the lastest version (patches).

But unfortunately, still same issue...

[MindaugasVaiciu]

how do you test disk perfomance?

try hdparm -tT /dev/yourdisk

[J1mbo]

Is it using the perc 6 controller? does it have the battery-backup unit installed on it?

Please award points to any useful answer.

[perfectid]

Hi,

I exactly did the test as you described earlier.

The read buffer is ok (3000+ MB/sec), but the buffered read is below 30MB/sec.

However, I did the check with just creating random files with a size of 100MB, 500MB and 1GB, it never came above 20MB/sec, most of the time it's actually less then that. So really performance to cry about...

[perfectid]

Hi,

No this is just a base server. On-board controller of the DELL R200, with one disk attached.

This server isn't using a PERC or SAS controller.

The performance earlier was fine, after setting up the new VM's, it's really bad.

[perfectid]

Double post :S

[MindaugasVaiciu · Accepted solution]

i think it's not a bad result, it depends you disks,

for example my VM with CentOS 5.4 on HP BL460c G1 with RAID1 on 146GB SAS disks:

# hdparm -t /dev/sda

/dev/sda:

Timing buffered disk reads: 106 MB in 3.02 seconds = 35.05 MB/sec

VM runs on not updated ESXi 4

[nobbywfc]

In my case configuring smaller main memory like 512MB per VM caused very poor performance in web browsing. As soon as I increased it to 2GB, performance dramatically improved. Hope this is the case of your environment.