Hot answers tagged san
Disk fragmentation in VMs is just a fact of life for the reason you've described. In most workloads, it's not something that needs to be worried about. If you have workloads that do massive sequential IO, this might be a cause of poor performance, but not on random read/write workloads. There's a reason VMs are sometimes referred to as I/O blenders :)
Multiple I/O's are always less efficient. Whether it manifests as a performance issue would be something you need to determine. Some files by definition are large and have data organized randomly, so some split I/O's would be expected. Split I/O's can also be a symptom of another underlying bottleneck, such as disk queue length. You may want to ensure ...
For Netapp, split IO generally means bad alignment. If your MBR offsets the VM's disk blocks so that they span the borders of Netapp blocks, then each time you do IO on a single block from the OS, you're having to hit the storage twice.
The rationale behind this in RFC 3720 is that above all, IQNs should be unique. The date prepended is a reasonable guarantee that the entity that controlled the domain name represented (in the naming auth field) at that time a "naming authority" who could ensure uniqueness - domain names change hands all the time and since the only other unique stuff going ...
On mine to NETAPP: ls /proc/scsi/qla2xxx 1 ls /proc/scsi/qla2xxx/1 | grep -i -A1 -B1 "queue depth" Total number of interrupts = 30686605 Device queue depth = 0x20 Number of free request entries = 1842 So x20 is 32 in decimal, This is the # you are looking for. You can read about calculation for NETAPP here: ...
There's a very small overhead on each frame. Max transfer size on the HBA being set too small can cost you a bit of overhead from sending more frames than needed, but the default (512KB) is larger than a standard FC frame (2148 bytes, 2112 bytes of it as payload). Each transfer from the HBA will be broken up into a sequence of frames anyways. You can use ...
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