Symmetrix Optimizer improves array performance by continuously monitoring access patterns and migrating devices (Symmetrix logical volumes) to achieve balance across the disks in the array.
Step 1: Symmetrix Optimizer builds a database of device activity statistics on the Symmetrix back-end.
Step 2: Using the statistical data collected, configuration information, and the user-defined parameters, the Optimizer algorithm identifies busy and idle devices and their locations on the physical drives. The algorithm tries to minimize average disk service time by balancing I/O activity across physical disks. Optimizer determines which disks require balancing by locating busy devices close to each other on the same disk, and/or by locating busy devices on faster disks or faster areas of the disks. Optimizer takes into account the speed of the disk, the disk geometry, and the actuator speed to determine faster disks.
Step 3: Once a solution for load balancing has been developed, the next phase is to carry out the Symmetrix device swaps. This is done using established Time Finder technology, which maintains data protection and availability. We can specify whether swaps should occur in a completely automated fashion, or if the device swaps require user approval before the action is taken.
Step 4: Once a swap function completes, Symmetrix Optimizer continues data analysis for the next swap.
We cannot create Disk Groups; it should be done by changing BIN file by CE.
We can rename the existing disk groups.
Example: symconfigure -Sid 207 -cmd “set disk_group 4 disk_group_name = flash_dsks;” -v -nop commit.
To monitor real time 100 event records with 600 seconds interval in the symmetrix array.
Symevent -sid 4282 monitor -i 600 -c 100 -warn/-error/-fatal.
To create access control list on symmetrix array to implement host level or user level security.
Stripped Meta Devices:
Meta device addressing by striping divides each Meta member device into a series of stripes, addressing a stripe from each device before advancing to the next stripe on the first device. When writing to a striped volume, equal size stripes of data from each participating drive are written alternately to each member of the set.
Concatenated Meta Devices:
Concatenated devices are volume sets that are organized with the first byte of data at the beginning of the first device. Addressing continues to the end of the first device before any data on the next device is referenced. When writing to a concatenated device, the first meta device member receives all the data until it is full, and then data is directed to the next member and so on.
This feature will automatically selects and assigns the LUN IDs to the devices while device mapping to the port Instead of manually assigning address to the device while mapping.
It is a database file in the host which stores the symmetrix array configuration data.
Can be used to get the configuration data offline.
Maximum Cylinders = 65520
Maximum Capacity = 59GB or 61425 MB
Symcfg -Sid 4282 list -connections -capacity
Copy and paste the output of the above command in excel file and format according to the requirement.
Set up or update the Symmetrix array user authorization information.
By Disk Group: Symdisk -Sid XXXX list -by_diskgroup.
Array as whole: Symconfigure -Sid XXXX list –freespace.
User-to-role mappings have to be created:
(Create a command file with the following entry (ex: rolemap.txt))
Assign user H: Host username to role Monitor;
Assign user D: Eng username to role Admin;
(Execute the above file)
Symauth -sid 4282 -f rolemap.txt commit.
(Roles: None, Monitor, Storage admin, admin, Auditor, SecurityAdmin)
Enable the user authorization:
Symauth -Sid 4282 enable.
Symacl -sid 4282 backup -file "command file"
Symacl -sid 4282 commit -restore -f command file
The device masking database (VCMDB) holds device masking records and typically resides on a 24 or 48 cylinder disk device.
Symmaskdb -Sid XXXX backup -f filename.
256 LUN IDs are available per FA port, 255 LUN IDs are usable out of 256.
Vault Drivers: At the time of emergency shutdown of an Array, whatever the data in cache memory will be destaged/saved on temporary drives called vault drives.
Hot Spare: At the time of physical drive failure hot spare drives will take place.
Symcfg -Sid XXXX -SA all list -v
Set Symmetrix MatricName=MatricValue
Symmetrix external locks are used by SYMAPI (locks 0 to 15) and also for applications assigned by EMC (>15) to lock access to the entire Symmetrix array during critical operations.
Quality of Service (QoS) allows more flexibility in managing Symmetrix system’s performance. By increasing the response time for specific copy operations on selected devices, we can increase the overall performance of the other Symmetrix devices.
Using Performance Monitoring feature in EMC Control Center.
Using SYMSTAT symcli command.
Thin provisioning is a method of optimizing the efficiency with which the available space is utilized in storage area networks. Thin provisioning operates by allocating disk space in a flexible manner among multiple users, based on the minimum space required by each user at any given time.
REQUESTS: Reports I/O requests and throughput for selected devices, directors, or SRDF/a session. (This is the default type; if no type is specified REQUESTS is used.)
BACKEND: Reports back-end I/O requests and throughput for selected devices.
PORT: Reports performance statistics for a director port. ISCSI Report Gig-E network statistics.
CACHE: Reports cache activity for selected front-end or remote link directors, or SRDF/A sessions.
MEMIO: Reports cache memory to disk activity for selected devices. PATH Report R-Copy path information for no incremental sessions. Symmetrix arrays that have all or some incremental sessions will report an error.
CYCLE: Report cycle summary information for SRDF-A sessions.
DISK: Reports back-end I/O requests and throughput for selected disks.
PREFETCH: Reports track prefetch disk activity for selected back-end director’s only.DMSP Reports dynamic mirroring service policy (DMSP) statistics for the selected device(s).
RDF: Reports SRDF statistics from the perspective of RA groups, devices, or directors.
Symauth -Sid 4282 backup -f backupfile.cmd commits
Symauth -Sid 4282 restore -f backupfile.cmd commit
To list all events in symmetrix array
Symevent -Sid 4282 list
To list specific period of time events in event logs
Symevent -Sid 4282 list -vs -start 9:00 -end 17:00