Bad Performance : High IO Delay

[BiagioParuolo]

Hi,

I've a I/O delay 40/50% ( media ).

Question:

I've a 30Gb qcow2 disk on KVM Win2k3 Machine.

Is't good to split this disk in two disk: 10Gb one disk ( where is system operative ) and 20Gb the second?
Is't good to pass to raw?

Thanks

 

[tom]

Hi,

I've a I/O delay 40/50% ( media ).

Question:

I've a 30Gb qcow2 disk on KVM Win2k3 Machine.

Is't good to split this disk in two disk: 10Gb one disk ( where is system operative ) and 20Gb the second?
Is't good to pass to raw?

Thanks

if you use raw, you can probably get a bit extra performance in some situations. splitting the disk can make sense, but I see not performance boost here.

if you need top performance, think of using block devices directly (LVM/SAN).

 

[BiagioParuolo]

... using block devices directly

May I to create a new disk partition and use LVM?

 

[BiagioParuolo]

My RAID Controller:

LSI Logic / Symbios Logic SAS1064ET PCI-Express Fusion-MPT SAS (rev 02)

 

[tom]

My RAID Controller:

LSI Logic / Symbios Logic SAS1064ET PCI-Express Fusion-MPT SAS (rev 02)

pls run the following command when the server is NOT under load:

pveperf

 

[BiagioParuolo]

CPU BOGOMIPS: 20000.10
REGEX/SECOND: 634325
HD SIZE: 56.84 GB (/dev/pve/root)
BUFFERED READS: 102.49 MB/sec
AVERAGE SEEK TIME: 16.27 ms
FSYNCS/SECOND: 110.18
DNS EXT: 74.70 ms
DNS INT: 10.74 ms (redconsulting.xy)

 

[dietmar]

AVERAGE SEEK TIME: 16.27 ms

Looks you use really slow disks. A good disk is up to 3 times faster.

FSYNCS/SECOND: 110.18

This should be greater than 1500 - seems there is something wrong with your cache settings on the RAID controller. Use write-back mode (you need a BBU to use that option).

 

[udo]

Hi,
i think the problem is the lsi-controller! I have one lsi-onboard on a blade and the performance are also very bad (two sata disk as raid1):

CPU BOGOMIPS:      25540.36
REGEX/SECOND:      602183
HD SIZE:           49.22 GB (/dev/pve/root)
BUFFERED READS:    36.12 MB/sec
AVERAGE SEEK TIME: 13.62 ms
FSYNCS/SECOND:     116.22
DNS EXT:           116.13 ms
DNS INT:           0.58 ms

Only usefull with external storage (FC).

Udo

 

[dietmar]

Hi,
i think the problem is the lsi-controller! I have one lsi-onboard on a blade and the performance are also very bad (two sata disk as raid1)

Those numbers indicated a wrong cache setup on the raid controller.

 

[BiagioParuolo]

I speak with my ISP where I rent my dedicated server and says me that controller have not mem cache.

Then, I think if we use a RAID software ( some ISP gives dedi server with RAID sw ) we'll have a bad bad performance...

 

[dietmar]

I speak with my ISP where I rent my dedicated server and says me that controller don't have mem cache.

Then you need to enable the cache on the disk to get better performance.

 

[BiagioParuolo]

Then you need to enable the cache on the disk to get better performance.

How?

 

[dietmar]

How?

That depends on you harddisk - consult HD docs - maybe the HD vendor provide a tool.