[PVE-User] I/O issues

[Martin Maurer]

> Subject: Re: [PVE-User] I/O issues
> 
> Well the version does not seem to make a difference much at all:
> 
> proxmox_1.1:/# pveperf
> CPU BOGOMIPS:      42564.52
> REGEX/SECOND:      739582
> HD SIZE:           68.41 GB (/dev/pve/root)
> BUFFERED READS:    122.05 MB/sec
> AVERAGE SEEK TIME: 5.05 ms
> FSYNCS/SECOND:     150.74
> 
> 
> proxmox_1.3:/# pveperf
> CPU BOGOMIPS:      42564.51
> REGEX/SECOND:      663579
> HD SIZE:           68.41 GB (/dev/pve/root)
> BUFFERED READS:    112.45 MB/sec
> AVERAGE SEEK TIME: 5.08 ms
> FSYNCS/SECOND:     153.96

This is quite clear: fast disks (I mean 10k or faster) and NO cache enabled on the raid controller. a controller with no BBU normally disables the cache.

> 
> I ran pveperf on another machine and I got these numbers:
> 
> CPU BOGOMIPS:      39904.42
> REGEX/SECOND:      797648
> HD SIZE:           130.32 GB (/dev/sda2)
> BUFFERED READS:    120.10 MB/sec
> AVERAGE SEEK TIME: 5.33 ms
> FSYNCS/SECOND:     3069.82

That's what you can expect from this kind of system, fast drives and raid controller cache. Take a look on this thread: http://www.proxmox.com/forum/showthread.php?t=296


> 
> It looks like the slower machines are using:
> 
> 300G, Serial Attached Scsi.10k, 2.5, Seagate Firefly
> 
> and the faster one (FSYNCS/SECOND) are using these:
> 
> 146G, Serial Attached SCSI, 15K, 3.5, Seagate, 15K
> 
> The faster systems are using a different raid controller and the
> megaraid_sas diver (vs mptsas in the slower system) as well...so I can
> only really wait on the PERC 6I RAID card to get here and test it.
> 
> Now I am wondering if it is not the RAID card but the drives that are
> the issue...or a combination of both.  Should 10K SAS drives give better
> numbers then 'FSYNCS/SECOND:     153.96'?

it's all about the raid controller cache. I really like the adaptec cards (e.g. 5805) as they got a really nice management interface (ASM) which can be installed on Proxmox VE. Using the ASM, you can check the disk cache and controller cache settings. I assume other management tools can do this also.
For the adaptec, see http://pve.proxmox.com/wiki/Adaptec_Storage_Manager

Br, martin

> 
> 
> Thanks,
> 
> Shain
> 
> 
> 
> 
> Martin Maurer wrote:
> >> No these are not SSD's.  They are SAS drives.  I am going to try an
> >> install of 1.1 on one of these DELL's then upgrade to 1.2 and then to
> >> 1.3 and run pveperf each time.  I found another machine v1.1 withe
> the
> >> same  RAID card and the numbers are not as bad as the ones from 1.3.
> I
> >> am wondering it is some change in the kernel that is responsible for
> the
> >> poor performance.
> >>
> >> I will post the numbers in a few hours so I can get some feedback.
> >>
> >> Thanks,
> >>
> >> Shain
> >>
> >
> >
> > I just want to show you the results you can get with SSD, just FYI -
> our results with the Samsung ssd.
> > Sorry for the unclear comment,
> >
> > Br, martin
> >
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> >
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