On 08/02/13 10:48, Chris Murphy wrote: > > ***On Feb 7, 2013, at 6:08 AM, Adam Goryachev > <mailinglists@xxxxxxxxxxxxxxxxxxxxxx> wrote: >> Basically, on occasion, when a user copies a large file from disk >> to disk, or when a user is using Outlook (frequently data files are >> over 2G), or just general workload, the system will "stall", >> sometimes causing user level errors, which mostly affects Outlook. > > Does this concern anyone else? In particular the user doing "disk to > disk" large file copies. What is this exactly? LV to LV with iSCSI > over 1gigE? Why did you reject NFS for these physical Windows boxes > and their VMs to access this storage, rather than what I assume is > NTFS over iSCSI, because of this statement? This isn't a common thing (well, it happens once a week when a user logs in after hours to do some sort of backup/DB maintenance), but it is the easiest way to reproduce the problem, and from the evidence, it seems to match. ie, generally the problem is characterized as: 1) Large amount of read and write on one iSCSI device 2) User complain about write failures, slow response, etc even when 1 and 2 are on different VM's (which are on different physical machines). >> Each LV is then exported via iSCSI > That block device needs a file system for Windows to use it. > > It also seems to me one or more of these physical servers running > VMs, with only 1gigE to the storage server, need either additional > pipes LACP or bonded ethernet, or 10gigE. I can just imagine one > person doing a large file copy disk to disk, which is a single pipe > doing a pull push, double NTFS packet overhead, while all other > activities get immensely hit with network latency as a result. However, this should only cause issues for users on the server which is doing this. ie, if a user logs into terminal server 1, and copies a large file from the desktop to another folder on the same c:, then this terminal server will get busy, possibly using a full 1Gbps through the VM, physical machine, switch, to the storage server. However, the storage server has another 3Gbps to serve all the other systems. Also, 100MB/s is not an unreasonable performance level for a single system (ok, minus overhead, even 60MB/s would probably equal what they had before with 10 year old SCSI disks). > ###On Feb 7, 2013, at 4:07 AM, Dave Cundiff <syshackmin@xxxxxxxxx> > wrote: > >> See page 17 for a block diagram of your motherboard… Your SSDs >> alone could saturate that if you performed a local operation. Get >> your NIC's going at 4Gig and all of it a sudden you'll really want >> that SATA card in slot 4 or 5. > > Yeah I think it needs all the network performance and reduced latency > as he can get. I'll be surprised if the SSD tuning alone makes much > of a dent with this. I still need to go in (tomorrow night) and pull apart the machine physically to confirm which slot the network cards are in, but based on the other comments, I don't think this is the limiting factor.... Slap me if it is and I'll drive in tonight and check it sooner. Thanks, Adam -- Adam Goryachev Website Managers www.websitemanagers.com.au -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
