On 2/2/2015 8:11 PM, Jatin Davey wrote:> disk 252:1 | 0-0-0 | 9XG7TNQVST91000640NS CC03 | Online, Spun Up > disk 252:2 | 0-0-1 | 9XG4M4X3ST91000640NS CC03 | Online, Spun Up > disk 252:3 | 0-1-1 | 9XG4LY7JST91000640NS CC03 | Online, Spun Up > disk 252:4 | 0-1-0 | 9XG51233ST91000640NS CC03 | Online, Spun Up > End of Output ************************** > > Let me know if i need to change or configure anything else to make the > I/O a bit faster than what it currently does. I cannot go in for using > SSD's due to budget constraints. Need to make the best use of the SATA > disks that i have currently.so, you have 2x2 ST91000640NS http://www.seagate.com/products/enterprise-servers-storage/nearline-storage/enterprise-capacity-2-5-hdd/ those are "Nearline" disks, 7200RPM. They are intended for bulk secondary storage, archives, backups and such. you said you have a number of virtual machines all attempting to access this raid10 at once? I'm not surprised that it is slow. You're probably limited by random IO/second, that raid likely does around 250 random operations/second. share that between 6-7 virtual systems and if they are all doing disk IO, they are going to slow down each other. -- john r pierce 37N 122W somewhere on the middle of the left coast
On 2/3/2015 10:00 AM, John R Pierce wrote:> On 2/2/2015 8:11 PM, Jatin Davey wrote: >> disk 252:1 | 0-0-0 | 9XG7TNQVST91000640NS CC03 | Online, Spun Up >> disk 252:2 | 0-0-1 | 9XG4M4X3ST91000640NS CC03 | Online, Spun Up >> disk 252:3 | 0-1-1 | 9XG4LY7JST91000640NS CC03 | Online, Spun Up >> disk 252:4 | 0-1-0 | 9XG51233ST91000640NS CC03 | Online, Spun Up >> End of Output ************************** >> >> Let me know if i need to change or configure anything else to make >> the I/O a bit faster than what it currently does. I cannot go in for >> using SSD's due to budget constraints. Need to make the best use of >> the SATA disks that i have currently. > > so, you have 2x2 ST91000640NS > http://www.seagate.com/products/enterprise-servers-storage/nearline-storage/enterprise-capacity-2-5-hdd/ > > > those are "Nearline" disks, 7200RPM. They are intended for bulk > secondary storage, archives, backups and such. > > you said you have a number of virtual machines all attempting to > access this raid10 at once? I'm not surprised that it is slow. You're > probably limited by random IO/second, that raid likely does around 250 > random operations/second. share that between 6-7 virtual systems and > if they are all doing disk IO, they are going to slow down each other. > > > >So , You dont think that any configuration changes like increasing the number of volumes or anything else will help in reducing the I/O wait time ? Thanks Jatin
On 2/2/2015 8:52 PM, Jatin Davey wrote:> So , You dont think that any configuration changes like increasing the > number of volumes or anything else will help in reducing the I/O wait > time ?not by much. it might reduce the overhead if you use LVM volumes for virtual disks instead of using files, but if you're doing too much disk IO, there's not much that helps other than faster disks (or reducing the amount of reads by more aggressive caching via having more memory). -- john r pierce 37N 122W somewhere on the middle of the left coast
On 02/02/2015 08:52 PM, Jatin Davey wrote:> So , You dont think that any configuration changes like increasing the > number of volumes or anything else will help in reducing the I/O wait > time ?No, because that won't change the number of heads that are present to service the IO requests, nor to segregate requests effectively. Your primary goals should be to reduce IO (investigate using LVM backed VMs instead of file-backed) or to increase hardware resources (possibly a larger number of smaller disks if SSDs are not in budget).