# " Split I/O" s on a Linux VM, disk placement

I'm attempting to identify if there is some means I can inform if a system is being detrimentally influenced by disk imbalance - - i.e. when I do a disk I/O procedure, it in fact requires to demand added blocks from the backside storage space (we are making use of a SAN) due to the fact that the asked for block of information in fact survives numerous blocks on the real disk.

This trouble purportedly influences VMs a lot more, as the disks are extracted to make sure that blocks do not straighten as a result of inappropriate field offsets, creating added IOPS to be made use of when accessing the backend storage space from the VM.

Anyhow, I've been considering iostat result, and also it feels like there is information there that could offer me an idea to this, yet I appear to be slow-moving at thinking via it. Exists some idea to show with iostat (or another thing) that the equipment could be executing even more disk I/Os that optimum?

(I'm not encouraged that disk placement deserves the initiative to investigate/worry around, yet I would certainly enjoy some point of views on the issue!)

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2019-05-18 22:38:27
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I usually consider sar result to see if Disk I/O is reaching be a trouble. You will certainly see ordinary line up dimension and also solution times raising when you have an I/O trouble. Then you require to start considering why I/O is a trouble. With a SAN it can take place at a variety of areas. There are a selection of remedies. For digital equipments, I would certainly lean to different SAN disks for each and every equipment. These can be alloted as raw disks to the digital equipments as opposed to among the digital disk in a documents layouts like VMDK.