Testking VCP-410
o You cannot use IDE/ATA drives to store virtual machines.
o Use local SATA storage, internal and external, in unshared mode only.
o Some SAS storage systems can offer shared access
o You can have up to 256 VMFS datastores per system, with a minimum volume size of 1.2GB.
o Grow the existing datastore extent if the storage device where your datastore resides has free space. You can grow the extent up to 2 TB.
o You can connect up to 220 701 32 hosts to a single VMFS volume. (EDIT: Maximums document says 64)
o Perform a rescan each time you:
o Create new LUNs on a SAN.
o Change the path masking on a host.
o Reconnect a cable.
o Make a change to a host in a cluster.
o Do not rescan when a path is unavailable.
o To rescan adapters on all hosts managed by vCenter by right-clicking a datacenter, cluster, or folder and selecting Rescan for Datastores.
o ESX does not support the delegate user functionality that enables access to NFS volumes using non-root credentials
o Disk format on a NAS device is dictated by the NFS server, typically a thin format that requires on-demand space allocation.
o When your host accesses a virtual machine disk file on an NFS-based datastore, a .lck-XXX lock file is generated to prevent other hosts from
accessing this file.
o If the underlying NFS volume, is read-only, make sure that the volume is exported as a read-only share by the NFS server, or configure it as a
read-only on the ESX host.
o A diagnostic partition cannot be located on an iSCSI LUN accessed through a software iSCSI initiator.
o You can query and scan the host’s diagnostic partition using the vicfg-dumppart -l command
o You can group datastores into folders.
o You can unmount:
o NFS datastores
o VMFS datastore copies mounted without resignaturing
o You can have up to 32 extents.
o You can grow an extent in an existing VMFS datastore. Only extents with free space immediately after them are expandable.
o If a shared datastore has powered on virtual machines and becomes 100% full, you can increase the datastore’s capacity only from the host,
with which the powered 220 702 on virtual machines are registered.
o You can mount a VMFS datastore only if it does not collide with an already mounted VMFS datastore that has the same UUID (signature).
o When resignaturing a VMFS copy, ESX assigns a new UUID and a new label to the copy, and mounts the copy as a datastore distinct from the
original.
o The default format of the new label assigned to the datastore is snap-<snapID>-<oldLabel>, where <snapID> is an integer and <oldLabel> is the
label of the original datastore.
o Datastore resignaturing is irreversible.
o A spanned datastore can be resignatured only if all its extents are online.
o Pluggable Storage Architecture (PSA) is an open modular framework that coordinates the simultaneous operation of multiple multipathing
plugins (MPPs). The VMkernel multipathing plugin that ESX provides by default is the VMware Native Multipathing Plugin (NMP). Two types of
NMP subplugins, Storage Array Type Plugins (SATPs), and Path Selection Plugins (PSPs).
o The VMware NMP supports all storage arrays listed on the VMware storage HCL and provides a default path selection algorithm based on the
array type.
o ESX offers an SATP for every type of array that VMware supports.
o By default, the VMware NMP supports the following PSPs:
o Most Recently Used (MRU)
o Fixed - with active-passive arrays that have a Fixed path policy, path thrashing might be a problem.
o Round Robin (RR) - Uses a path selection algorithm that rotates through all available paths enabling load balancing across the paths.
o Claim rules defined in the /etc/vmware/esx.conf file, the host determines which multipathing plugin (MPP) should claim the paths.
o By default, the host performs a periodic path evaluation every 5 minutes.
o Active multiple working paths currently used for transferring data are marked as Active (I/O). In ESX 3.5 or earlier, the term active means the
only path that the host is using to issue I/O to a LUN.
o Standby path is operational and can be used for I/O if active paths fail.
o If you created a virtual disk in the thin format, you can later inflate it to its full size.
o RDM offers several 220 701 benefits. User-Friendly Persistent Names, Dynamic Name Resolution, Distributed File Locking, File Permissions, File System
Operations, Snapshots, vMotion, SAN Management Agents and N-Port ID Virtualization(NPIV).
o Certain limitations exist when you use RDMs:
o Not available for block devices or certain RAID devices.
o Available with VMFS-2 and VMFS-3 volumes only.
o No snapshots in physical compatibility mode.
o No partition mapping. It requires a whole LUN.
