I thought I would provide some more information related to the below email...
After some exhaustive tests, I have identified the problem was not really network performance. It was moreso disk overhead related to the use of a zfs backend store. As I understand it, the process of copying the file involved reading from network in primary. The guest domain then reads the data from its vnet and writes to its filesystem. This, in turn, writes to the guest's vdisk. This write to the vdisk is then written to the primary domain as another copy operation. All of this occurrs prior to the physical write to the disk happens. The issue is compounded when the backend store is a file, as it is with zfs, instead of a device. In conclusion, I suppose that using a zfs backend store with LDoms is simply not an optimal solution. I will likely reconfigure the system to eliminate the zfs backend store in favor of a hardware RAID. > -----Original Message----- > From: Miller, Vincent (Rick) > Sent: Thursday, March 25, 2010 2:27 PM > To: '[email protected]' > Subject: T5120 Ldom Network Performance > > Hello all, > > I am hoping that I can gain an understanding based on some > things I have been trying to do. > > I have a T5120 w/ Solaris 10 10/09 with the latest available > firmware updates applied. Before installing and enabling > LDoms 1.3, I get respectable transfer rates over the e1000g > interfaces (about 2 minutes to transfer a 4GB file) over > Gig-E. However, after installing LDoms and creating the > services within the control domain, then creating a guest > LDom, I attempt to transfer the same 4GB file and now it > takes 8 - 10 mins to transfer. I have a pretty typical > configuration, at least compared to the Sun/Oracle docs for > the software. > > The OS indicates, through dladm, that the link is up at > 1000fdx. The switch on the other end of the link indicates > the same. However, upon visual inspection, the e1000g0 link > on the rear of the server is orange, when I expect green. > Seems to indicate a less than optimal link. > > In reviewing the release notes for LDoms 1.3, I found a known > issue identified as Bug ID 6486234. That seems to indicate > that network performance on T2 systems is considerably worse > than on systems where LDoms > 1.3 is not configured. In fact, this bug seems to be > referenced in the release notes for several releases. The > release notes go on to explain that a workaround is to > "assign a Network Interface Unit (NIU) to the logical domain". > > Ok. Great...I'll try that. Except the instructions I found > to accomplish this task seem to indicate that the on-board > e1000g interfaces are not NIU capable interfaces, thus > requiring the addition of a PCI network card. I gleaned this > information from > http://blogs.sun.com/raghuram/entry/niu_hybrid_i_o. which states, > specirfically: > > "NIU has support for 2 ports. Both T5120 and T5220 have two > slots for NIU, that is one slot for each port. The XAUI > adapters need to be installed in order gain access to the NIU ports." > > Additionally, if I configure the e1000g interface to support > the hybrid mode anyway, it simply does not have an impact on > performance. > > I guess what I am asking is if my assumptions are correct. > Is it generally accepted that network performance within a > LDom system will be poor? To correct this, is it the case > that I would need to install a NIU-capable NIC? > > -- > Take care > Rick Miller >
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