We have discussed regarding Symmetric DMX-3. Lets talk about Symmetrix Device. DMX-3 system applies a high degree of virtualization between what host sees and the actual disk drives. This device has logical volume address that the host can address. Let me clear that “A symmetrix Device is not a physical disk.” Before actually hosts see the symmetrix device, you need to define path means mapping the devices to Front-end director and then you need to set FA-PORT attribute for specific Host. Let not discuss configuration details now. I am trying to explain what Symmetrix device is if this is not physical disk and how it will be created.
You can create up to four mirrors for each Symmetrix device. The Mirror positions are designed M1, M2, M3 and M4. When we create a device and specify its configuration type, the Symmetrix system maps the device to one or more complete disks or part of disks known as Hyper Volumes/Hypers. As a rule, a device maps to at least two mirror means hypers on two different disks, to maintain multiple copies of data.
What is “Tier 0” in Storage Environments?
Tier "0" is not new in storage market but for implementation purposes it has been difficult to accommodate because it requires best performance and lowest latency. Enterprise Flash disks (Solid State Disks) capable to meet this requirement. It is possible to get more performance for company most critical applications. The performance can be gained through using Flash drives supported in VMAX and DMX-4 systems. Read More →
Most of user asked me what are basic differences between EMC Clone/Mirror/Snapshot? This is really confusing terminology because most of things will be same logically.Only thing change that is implementation and purpose of uses. I am trying to write basic and common differences:
1) A clone is a full copy of data in a source LUN. A snapshot is a point-in time "virtual" copy that does not occupy any disk space.
2) A snapshot can be created or destroyed in seconds, unlike a clone or mirror. A clone, for example, can take minutes to hours to create depending on the size of the source LUN.
3) A clone or mirror requires exactly the same amount of disk space as the source LUN. A snapshot cache LUN generally requires approximately 10% to 20% of the source LUN size.
4) A clone is an excellent on-array solution that enables you to recover from a data corruption issue. Mirrors are designed for off-site data recovery.
5) A clone is typically fractured after it is synchronized while a mirror is not fractured but instead is actively and continuously being synchronized to any changes on the source LUN.
Clones and mirrors are inaccessible to the host until they are fractured. Clones can be easily resynchronized in either direction. This capability is not easily implemented with mirrors.
Restoring data after a source LUN failure is instantaneous using clones after a reverse synchronization is initialized. Restore time from a snapshot depends on the time it takes to restore from the network or from a backup tape.
Once a clone is fractured, there is no performance impact (that is, performance is comparable to the performance experienced with a conventional LUN). For snapshots, the performance impact is above average and constant due to copy on first write (COFW).
I left one more term EMC BCV(Business Continuity Volume). It is totally different concept thought. I will try to cover in upcoming post though I have discussed about EMC BCV in my older post. But it is more or less cloning only only implementation change.
As we know that we have different type of RAID but all the raid type are not suitable for the all application. We select raid type depending on the application and IO load/Usages. Actually there are so many factor involved before you select suitable raid type for any application. I am trying to give brief idea in order to select best raid type for any application. You can select raid type depending on your environment.
When to Use RAID 5
RAID 5 is favored for messaging, data mining, medium-performance media serving, and RDBMS implementations in which the DBA is effectively using read-ahead and write-behind. If the host OS and HBA are capable of greater than 64 KB transfers, RAID 5 is a compelling choice.
These application types are ideal for RAID 5:
1) Random workloads with modest IOPS-per-gigabyte requirements
2) High performance random I/O where writes represent 30 percent or less of the workload
3) A DSS database in which access is sequential (performing statistical analysis on sales records)
4) Any RDBMS table space where record size is larger than 64 KB and access is random (personnel records with binary content, such as photographs)
5) RDBMS log activity
6) Messaging applications
7) Video/Media
When to Use RAID 1/0
RAID 1/0 can outperform RAID 5 in workloads that use very small, random, and write-intensive I/O—where more than 30 percent of the workload is random writes. Some examples of random, small I/O workloads are:
1) High-transaction-rate OLTP
2) Large messaging installations
3) Real-time data/brokerage records
4) RDBMS data tables containing small records that are updated frequently (account balances)
5) If random write performance is the paramount concern, RAID 1/0 should be used for these applications.
When to Use RAID 3
RAID 3 is a specialty solution. Only five-disk and nine-disk RAID group sizes are valid for CLARiiON RAID 3. The target profile for RAID 3 is large and/or sequential access.
Since Release 13, RAID 3 LUNs can use write cache. The restrictions previously made for RAID 3—single writer, perfect alignment with the RAID stripe—are no longer necessary, as the write cache will align the data. RAID 3 is now more effective with multiple writing streams, smaller I/O sizes (such as 64 KB) and misaligned data.
RAID 3 is particularly effective with ATA drives, bringing their bandwidth performance up to Fibre Channel levels.
When to Use RAID 1
With the advent of 1+1 RAID 1/0 sets in Release 16, there is no good reason to use RAID 1. RAID 1/0 1+1 sets are expandable, whereas RAID 1 sets are not.
To register the host’s HBAs with the storage system, start the Navisphere Agent as follows:
1. On the Windows host, right click My Computer and select Manage.
2. Click Services and Applications and then click Services.
3. Find EMC Navisphere Agent service.
4. If already started, stop the EMC Navisphere Agent service.
5. Start the EMC Navisphere Agent service.
AIX
To register the host’s HBAs with the storage system, on the AIX host, stop and start the Navisphere Agent. For example:
# rc.agent stop
HP-UX
To register the host’s HBAs with the storage system, on the HP-UX host,
stop and start the Navisphere Agent. For example:# /sbin/init.d/agent stop
Linux
To register the host’s HBAs with the storage system, on the Linux host, stop and start the Navisphere Agent. For example:
# /etc/init.d/naviagent stop
NetWare
To register the host’s HBAs with the storage system, on the NetWare host, restart the Navisphere Agent. In the NetWare server console screen, enter:
sys:\emc\agent\navagent.nlm -f
Solaris
To register the host’s HBAs with the storage system, on the Solaris host, stop and start the Navisphere Agent. For example:
# /etc/init.d/agent stop
VMware ESX server 2.5.0 and later
To register the host’s HBAs with the storage system, on the VMware host, stop and start the Navisphere Agent. For example:
# /etc/init.d/agent stop
I have been posting article related to CLARiiON recently. Lets talk about DMX Series. It is the most popular storage array from EMC. To manage DMX we have tool called ECC ( EMC Control Center, SMC and SYMCLI). Let me first explain what is gatekeeper and what is use?
To perform software operations on the Symmetrix, we use the low level SCSI command. To send SCSI commands to the Symmetrix, we need to open a device. We refer to the device we open as a gatekeeper. Symmetrix gatekeepers provide communication paths into the Symmetrix for external software monitoring and/or controlling the Symmetrix. There is nothing special about a gatekeeper, any host visible device can be used for this purpose. We do not actually write any data on this device, nor do we read any date from this device. It is simply a SCSI target for our special low level SCSI commands. We do perform I/O to these devices and this can interfere with applications using the same device. This is why we always configure small devices (NO data is actually stored) and map them to hosts to be used as "gatekeepers". Solutions Enabler will consider any device with 10 cylinders or less to be the preferred gatekeeper device.
Now you must have understood what is gatekeeper devices. Let me explain more about uses like how many gatekeeper you want to present host so there will be no performance impact.
A general recommendation for the number of gatekeepers for a single host with few applications running is 8. However, a common rule of thumb is a minimum of 6. For a host on which many applications running, 16 is recommended. A gatekeeper should not be mapped/masked to more than one host.
Granular Recommendation (for Solutions Enabler) :
It is hard to recommend an exact number of gatekeepers required for a single host. The number of gatekeeper's required depends on the specific host's configuration and role. This is because it directly relates to performance, therefore it is a subjective number. The following is a recommendation based upon a number of variables pertaining to that specific host. At least 2 gatekeepers for simple Solutions Enabler commands and 1 additional gatekeeper for each daemon or EMC Control Center Agent running on the host.
Granular Recommendation (for Control Center) :
• Two gatekeepers are required when the Storage Agent for Symmetrix is installed on the host, and two (total of four) additional gatekeepers are required when you use Symmetrix Configure commands to manage the Symmetrix system. Each Symmetrix system needs only two Symmetrix agents. The agents need to be installed on separate hosts. This is to provide for
failover when the primary agent goes down for maintenance (or failure).
• Common Mapping Agent and host agents do not require a gatekeeper.
• Note: SYMCLI scripts should not use gatekeepers assigned to ControlCenter; they should have their own.
Gatekeepers are typically 6 cylinders or 2888 KB in Size. All gatekeeper type devices should be protected by either RAID-1 or RAID-S.
Hope this will help you in deciding number of gatekeeper to assign the host.Because it is matter of performance.
If you have a multihomed host and are running like :
· IBM AIX,
· HP-UX,
· Linux,
· Solaris,
· VMware ESX Server (2.5.0 or later), or
· Microsoft Windows
you must create a parameter file for Navisphere Agent, named agentID.txt
About the agentID.txt file:
Line1: Fully-qualified hostname of the host
Line 2: IP address of the HBA/NIC port that you want Navisphere Agent to use
For example, if your host is named host28 on the domain mydomain.com and your host contains two HBAs/NICs, HBA/NIC1 with IP address 192.111.222.2 and HBA/NIC2 with IP address 192.111.222.3, and you want the Navisphere Agent to use NIC 2, you would configure agentID.txt as follows:
host28.mydomain.com
192.111.222.3
To create the agentID.txt file, continue with the appropriate procedure for your operating system:
1. Using a text editor that does not add special formatting, create
or edit a file named agentID.txt in either / (root) or in a directory of your choice.2. Add the hostname and IP address lines as described above. This file should contain only these two lines, without formatting.
3. Save the agentID.txt file.
4. If you created the agentID.txt file in a directory other than root, for Navisphere Agent to restart after a system reboot using the correct path to the agentID.txt file, set the environment variable EV_AGENTID_DIRECTORY to point to the directory where you created agentID.txt.
5. If a HostIdFile.txt file is present in the directory shown for your operating system, delete or rename it. The HostIdFile.txt file is located in the following directory for your operating system:
AIX :- /etc/log/HostIdFile.txt
HP-UX :- /etc/log/HostIdFile.txt
Linux :- /var/log/HostIdFile.txt
Solaris :- /etc/log/HostIdFile.txt
6. Stop and then restart the Navisphere Agent.
NOTE: Navisphere may take some time to update, however, it should update within 10 minutes.
7. Once the Navisphere Agent has restarted, verify that Navisphere Agent is using the IP address that is entered in the agentID.txt file. To do this, check the new HostIdFile.txt file. You should see the IP address that is entered in the agentID.txt file.The HostIdFile.txt file is in the following directory for your operating system:
AIX :/etc/log/HostIdFile.txt
HP-UX :/etc/log/HostIdFile.txt
Linux :-/var/log/HostIdFile.txt
Solaris :-/etc/log/HostIdFile.txt
For VMware ESX Server 2.5.0 and later
1. Confirm that Navisphere agent is not installed.
2. Using a text editor that does not add special formatting, create or edit a file named agentID.txt in either / (root) or in a directory of your choice.
3. Add the hostname and IP address lines as described above. This file should contain only these two lines, without formatting.
4. Save the agentID.txt file.
5. If you created the agentID.txt file in a directory other than root, for subsequent Agent restarts to use the correct path to the agentID.txt file, set the environment variable EV_AGENTID_DIRECTORY to point to the directory where you created agentID.txt.
6. If a HostIdFile.txt file is present in the /var/log/ directory, delete or rename it.
7. Reboot the VMWARE ESX server.
8. Install and start Navisphere Agent and confirm that it has started.
NOTE: Before installing Navisphere Agent, refer to the EMC Support Matrix and confirm that you are installing the correct version.
NOTE: If necessary, you can restart the Navisphere Agent
NOTE: Navisphere may take some time to update, however, it should update within 10 minutes.
9. Once the Navisphere Agent has restarted, verify that Navisphere Agent is using the IP address that is entered in the agentID.txt file. To do this, check the new HostIdFile.txt file which is located in the /var/log/ directory. You should see the IP address that is entered in the agentID.txt file.
For Microsoft Windows:
1. Using a text editor that does not add special formatting, create a file named agentID.txt in the directory C:/ProgramFiles/EMC/Navisphere Agent.
2. Add the hostname and IP address lines as described above. This file should contain only these two lines, without formatting.
3. Save the agentID.txt file.
4. If a HostIdFile.txt file is present in the C:/ProgramFiles/EMC/Navisphere Agent directory, delete or rename it.
5. Restart the Navisphere Agent
6. Once the Navisphere Agent has restarted, verify that Navisphere Agent is using the correct IP address that is entered in the agentID.txt file. Either:
· In Navisphere Manager, verify that the host IP address is the same as the IP address that you you entered in the agentID.txt file. If the address is the same, the agentID.txt file is configured correctly.
· Check the new HostIdFile.txt file. You should see the IP address that is entered in the agentID.txt file.
We have discussed about CLARiiON. How to create LUN,RAID Group etc. before I shold discuss about adding storage to host. I must discuss about Navisphere Host agent. This is most important service/daemon which runs on host and communicate with CLARiiON. Without Host agent you can not resgister host with storage group automatically. Then if you want register host with Navishere Host agent then you need to register manually.
· Send drive mapping information to the attached CLARiiONstorage systems.
· Monitor storage-system events and can notify personnel by email, page, or modem when any designated event occurs.
· Retrieve LUN WWN (world wide name) and capacity information from Symmetrix storage systems.
About Me
- Diwakar
- Sr. Solutions Architect; Expertise: - Cloud Design & Architect - Data Center Consolidation - DC/Storage Virtualization - Technology Refresh - Data Migration - SAN Refresh - Data Center Architecture More info:- diwakar@emcstorageinfo.com
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