Luke S Crawford wrote: > My experience has been I can expect something between 70-100megabytes/sec > for 7500RPM, depending on where in the disk it is. if I get 50MB/sec > on the outer tracks, I assume the drive has a bunch of remapped sectors and > I send it back. (this is for 1.5TiB or 1TiB drives with 32MiB cache.) > > I only expect 120Megabytes/sec out of a 15K drive; The big win with 15K > drives is not sequential speed (the higher density of the sata drives > help with that) but random access speed. >
Drive bandwidth is definitely creeping up with storage density. On my laptop, the 100 GB 7200 RPM SATA drive gets 20-25 MB/sec, whereas the 500 GB 4200 RPM SATA drive sustains 50 MB/sec+. And this is just for 2.5" laptop drives. Gig-E can keep up with a single, typical drive stream these days (no, not with 15KRPM rockets!) - depending on protocol overhead, and on what else the interface is doing. We're moving to 10GbE for our larger servers and virtualisation platforms with multiple CPUs and connections to SAN. My first 10gE lab box should be here in a week or two, so I'll get to play with some of this for myself. Of course, 10GbE is only useful if your platform can push the data out the interface at line speed - the platform that I'm using is designed for it from the ground up, but putting a 10GbE interface into just 'any old backplane' is unlikely to give you stellar results (much like early GigE). And to he original question about virtualisation - we use VMware ESX extensively, and yes, we have Windows machines for the console service. My older lab machine contains one Windows VM for this purpose, it's mostly used to maintain the license nannyware used by our lab support team to keep us legal. I do most of my interface to the VMs via ssh and VNC, and it's possible to connect directly to the ESX server using Firefox to halt or reboot frozen VMs. VMware 'encourages' you to use the console server, but I've found that I'm not forced to do so for my small lab environment. I am an OS 'gourmand', so it doesn't bother me that I need to use Windows for some purposes to access the VMs (I run a Windows VM in VMware Server on my Linux laptop), it's just inconvenient that I need to run a Windows VM mostly to count licenses. I would rather put the memory and disk space toward something more useful, but there it is. ESX virtualisation is solid, we run a lot of our production services on it, and even more of the development environment. Our default is now to use VMs, exceptions are only granted with solid business cases (e.g., forced to run a software product where VMs are not supported by the vendor, or a service can't be broken down into pieces that will run on a max of four virtual CPUs each). - Richard _______________________________________________ Tech mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
