I/O Delay more than 55%

marcap

New Member
Apr 5, 2011
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Dear all,

I would like to run a distributed filesystem with proxmox ve containers. Unfortunately the IO Delay goes up to more than 55% if the clients are write/read something on the distributed filesystem.

I done pveperf:
Code:
CPU BOGOMIPS:      33601.78
REGEX/SECOND:      874813
HD SIZE:           94.49 GB (/dev/mapper/pve-root)
BUFFERED READS:    132.65 MB/sec
AVERAGE SEEK TIME: 11.69 ms
FSYNCS/SECOND:     1516.32
DNS EXT:           65.57 ms

That looks not really bad. But the containers of the guest installations are not lying at pve-root (theyre at pve-data). Do I need a faster disk or is there something else to tune? I want to avoid to invest in to much and/or expensive disks. I guess a SSD just for the pve-root will not help me in that case?
The guest system has actual 2048MB RAM, do you think more would be better?

The guests are running virtio disks with raw format.

Hope you have some good ideas!

Best regards,
Markus
 
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What exactly do you mean by "distributed file system"? There are many with pros & cons. Unless you're talking about the block level replication agent, DRDB?
 
Im trying to run glusterfs instances in this machine. So the Setup would be: 1 big (CPU/MEM) instance for Applications, one smaller (2GBMEM/2Cores of 6) for the gluster instance.
But if I write to the glusterfs the I/O delay gets higher an higher :(
 
Im trying to run glusterfs instances in this machine. So the Setup would be: 1 big (CPU/MEM) instance for Applications, one smaller (2GBMEM/2Cores of 6) for the gluster instance.
But if I write to the glusterfs the I/O delay gets higher an higher :(
Hi,
your performance-data looks like a normal sata-disk?!
For vitualization you need good IO - this is the reason why an good hardware-raidcontroller is suggested.
A ssd as system-disk help not much (i assume that your system don't swap), better if you use the ssd for the VMs (but here it's the same - the very cheap ssds are not faster than normal disks if you have many IOs; the better ssds are much faster!).

Udo
 
Hi,

Actual I have one SATA-Disk in there. What do you think is better:
  • 2x SATA 1,5TB + HW RAID (3Ware)
  • 1x SATA WD VelociRaptor 600GB
  • 1x SAS Disk 300GB

EDIT: Maybe 1x Seagate ST31000424SS would be also a nice option?

SSD's are really expensive if I want to have some GB Space. I would like prefer the VelociRaptor but will this decrese the I/O Delay observable??

Best regards
 
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Hi,

Actual I have one SATA-Disk in there. What do you think is better:
  • 2x SATA 1,5TB + HW RAID (3Ware)
  • 1x SATA WD VelociRaptor 600GB
  • 1x SAS Disk 300GB

EDIT: Maybe 1x Seagate ST31000424SS would be also a nice option?

SSD's are really expensive if I want to have some GB Space. I would like prefer the VelociRaptor but will this decrese the I/O Delay observable??

Best regards
Hi,
this is not easy!
Raid-1 is good, because your data are safe! But raid-1 is not really faster than a single disk - but the benefit of the raid-controller cache! See also here http://pve.proxmox.com/wiki/Raid_controller
If your SAS-Disk has 4ms seektime i would prefer this.
I have an raid with 4*Raptor300 as raid-10 and the different to an raid-10 with 4*SAS is huge (pveperf: 321.03 MB/sec Raptor-Raid and 439.96 MB/sec SAS-Raid - ok, it's also not the same raidcontroller).
My first attemps i made with PVE on sun-hardware with an ugly onboard lsi-raid-controller, and i would say without good io, there is not much fun...
I have no real experiences with single disks.

Udo