EMC Storage Product Knowledge Sharing

We have discussed about Virtual Provisioning of Symmetrix in previous post. Now, we will discuss about Virtual Provisioning Configuration. You have to understand your storage environment before you run the below mentioned command.

Configuring and viewing data devices and pools:

Data Devices are devices with datadev attribute. Only Data Devices can be part of Thin Pool. Devices with different protection scheme can be supported for use in Thin Pools. It is depending on specific Enginuity level. All devices with the datadev attribute are used for exclusively for populating Thin Pools.

Create command file (Thin.txt) with following syntax:

create dev count=10, config=2-Way-Mir, attribute=datadev, emulation=FBA, size=4602;

# symconfigure -sid 44 -file thin.txt commit –v –nop

A Configuration Change operation is in progress. Please wait...
Establishing a configuration change session...............Established.
Processing symmetrix 000190101244
{
create dev count=10, size=4602, emulation=FBA,
config=2-Way Mir, mvs_ssid=0000, attribute=datadev;
}
Performing Access checks..................................Allowed.
Checking Device Reservations..............................Allowed.
Submitting configuration changes..........................Submitted
…..
…..
…..
Step 125 of 173 steps.....................................Executing.
Step 130 of 173 steps.....................................Executing.
Local: COMMIT............................................Done.
Terminating the configuration change session..............Done.

The configuration change session has successfully completed.

# symdev list -sid 44 -datadev

Symmetrix ID: 000190101244
Device Name Directors Device
--------------------------- ------------- -------------------------------------
Sym Physical SA :P DA :IT Config Attribute Sts Cap(MB)
--------------------------- ------------- -------------------------------------
10C4 Not Visible ???:? 01A:C4 2-Way Mir N/A (DT) RW 4314
10C5 Not Visible ???:? 16C:D4 2-Way Mir N/A (DT) RW 4314
10C6 Not Visible ???:? 15B:D4 2-Way Mir N/A (DT) RW 4314
10C7 Not Visible ???:? 02D:C4 2-Way Mir N/A (DT) RW 4314
10C8 Not Visible ???:? 16A:D4 2-Way Mir N/A (DT) RW 4314
10C9 Not Visible ???:? 01C:C4 2-Way Mir N/A (DT) RW 4314
10CA Not Visible ???:? 16B:C4 2-Way Mir N/A (DT) RW 4314


Thin Pool can be created using symconfigure command and without adding data devices:

# symconfigure -sid 44 -cmd "create pool Storage type=thin;" commit –nop

Once pool is created, data devices can be added to the pool and enabled:

EMC announced Symmetrix V-Max recently which is based on virtual matrix. Symmetrix V-Max runs on latest Enginuity 5874. The 5874 plateform support Symmetricx V-Max Emulation level 121 and service processor level 102. The modular design of V-Max series Enginuity 5874 ensure flow and integrity between hardware component. Symmetrix Management Console 7.0 (SMC) integrated in service processor. SMC allows you to provision in 5 steps. Enginuity 5874 provides following enhanced feature:

Performance tuning has always been a challenge for System administrators and Database administrators for a long time. As virtualization continues to grow in every aspect of the IT infrastructure, tuning the OS, DB or storage tends to become even more complex.

Apart from CPU power and memory size, disk subsystem handles the movement of data on the computer system and has a powerful influence on its overall response. Also performance disk layout must also be designed to provide appropriate data protection with overall cost in mind.
Planning ahead is the most effective practice to avoid performance issues later on while also providing the flexibility to make adjustments before committing the changes into production.

Some fundamental disk terminology:

Alignment –Data block addresses compared to RAID stripe addresses
Coalesce – To bunch together multiple smaller IOs in one larger one
Concurrency – Multiple threads writing to disk simultaneously
Flush – Data in cache written to disk
Multi-pathing – Concurrent paths to same disk storage

How to choose a RAID type:

The concept of RAID is comprehensible to most in the storage industry. To extract the best disk performance, choosing the right RAID type based on IO patterns is very important. Most commonly observed IO patterns are listed later in the article. Since RAID 5 and RAID 1/0 are the most commonly used RAID types in the industry lets focus on these two for now.

RAID 1/0 – This RAID type works best for random IOs pattern especially for write-intensive applications. If the writes are above 20% go and RAID 1/0

RAID 5 – Compared to RAID1/0, for same number of physical spindles, the performance of the two is very close in a read-heavy environment. For instance, a 2+2 RAID 1/0 (total 4 disks) will perform similar to a RAID 5 3+1 (total 4 disks).

On the other hand, if one can afford to ignore the number of physical spindles and consider only the usable capacity (RAID 10 3+3 v/s RAID 5 3+1), RAID 1/0 is the way to go.

RAID1/0 has higher cost associated with it while RAID 5 provides a more efficient use of disk space. The only con associated with RAID 5 is the re-sync time after a disk replacement.

Number of Operations per RAID type:

RAID 1 and 1/0 require that two disks to be written for each host initiated write.
Total IO=host reads + 2* host writes
RAID5 (4+1) requires 4 operations per host write. If the data is sequential, do one large stripe write
A r5 write requires 2 reads and 2 writes
Total IO=host reads + 4*host writes

To re-cap,
. Parity RAID operations increase the disk load. For similar capacity, go for RAID1/0
. RAID5 is better than RAID1/0 for large sequential IO
. RAID 3 is much effective as you can now use cache with RAID 3
. RAID1/0 is best for mixed IO types.

Commonly noticed Database IO patterns:

OLTP Log – sequential
OLTP – Data – random
Bulk Insert - sequential
Backup – sequential read/write
Restore – sequential read/write
Re-index - sequential read/write
Create Database - Sequential read

Knowing your IO personality is important to choose which RAID type to consider. Using the above notes and application IO patterns, one can make a choice on the disk layout. Some characteristics of the IOs to consider are:
- IO size
- IO Read/Write ratio
- Type of IO - Random v/s Sequential
- Snapshots / Clones
- Application type – OLTP ?
- Bandwidth requirements
- Estimated Growth

Once you decide the type of RAID to use, you can fine tune the disk system by following vendor recommended practices like:

-- Lun distribution
-- Distribute the IO load evenly across available disk drives
-- Avoid using Primary and BCv/Snapshots luns on same physical spindles. (The best way to avoid this is to have separate disk groups for primary data disks and BCVs/Clones/Snapshots)
-- Consider using Meta or host stripping

Cache:
Disk writes are more costly and thus must be given bigger share of cache
Match cache page size to IO size to prevent multiple Ios

Stripe Size:
Retain default stripe size of 64KB
Larger the stripe size, more cache size required and longer it takes to rebuild

FC or iSCSI:
FC Best for large IO and high bandwidth
FC More expensive
iSCSI involves lowest cost
iSCSI works best for OLTP, small block IO

Some Best Practice recommendations from Microsoft:

Microsoft has laid a few guidelines for designing the SQL database
Use RAID1+0 for log files
Isolate log from data at physical disk level
Use RAID 1+0 for tempdb

Revisiting the above recommendations periodically to stay on track, will go a long way in extracting the best out of disks

--Contributed by Suraj Kawlekar

From its inception, Symmetrix was designed with the flexibility to incorporate the latest technology in disk drives, memory and other components. This effort has enabled the storage platform to evolve to meet the ever-increasing data demands of enterprises. and has provided customers with unparalleled investment protection. The first-generation Symmetrix 4400 Integrated Cached Disk Array (ICDA), with a total capacity of 24 gigabytes, was introduced in 1990. The seventh-generation system, the Symmetrix DMX-3, was introduced in July 2005 and features a Direct Matrix Architecture® and maximum capacity of one petabyte (1,024 terabytes). The Symmetrix platform has continued to improve and evolve to meet the needs of data-intensive organizations worldwide and remains the most successful intelligent storage platform in history.

With more than 68,000 systems shipped from its introduction in 1990 through the end of June, 2005 and with more than 400 EMC patents covering its technology, Symmetrix remains the high-end storage market leader and continues to set the standard for mission-critical high-end storage innovation.

1990 – Symmetrix 4200 – ICDA (Integrated Cached Disk Array) Technology, Total Capacity 24 GB

1991 – Symmetrix 4200 – 4Mb DRAM, 5.25 HDAs, Mirroring RAID 1

1992 – Symmetrix 4400 - - Dynamic Sparing, RMP Call Home

1993 – Symmetrix 4800 – 16MB DRAM, 1 GB Global Memory,Non-disruptive microcode, Hypervolume Extension.

1994 – Symmetrix 5500-3 – SRDF

1995 – Symmetrix 3.0 Open Symmetrix- FWD SCSI- attach, 3.5’’ HDAs, RAID Protection, SRDF Host Component, Symmetrix Manager

1996 – Symmetrix ESP – Mix CKD/FBA

1997 – Symmetrix 4.0 – TimeFinder, DataReach, InfoMover, Celerra, FDRSOS, Fibre Channel, PowerPath, UltraSCSI, DMSP

1998 – Symmetrix 4.8 – FC-AL/FC-SW, Symmetrix Optimizer

1999 – Symmetrix 5.0 – 333 MHz PPC, 181 GB disks, QoS Controls

2000- Symmetrix 5.5 – 2 GB fibre Channel, 400 MHz PPC

2000-2001 – Symmetrix DMX – Direct Matrix, 500 MHz PPC, 2 GB FC, Back-End Parity RAID

2001 – 2002 – Symmetrix DMX – 2 GB FICON, Gigabit Ethernet SRDF, iSCSI, SRDF/A, TimeFinder/Snap

2003- Symmetrix DMX-2 – 1 Ghz PPC, RAID 5 Data Protection, 32 GB Memory Directors

2003-2004- Symmetrix DMX-2- SRDF Mode Change, Concurrent SRDF, SRDF/Star, TimeFinder/Clone, Open Replicator

2005 – Symmetrix DMX-3 – 8 Processors/Directors, 1.3 GHz PPC, Low Cost FC Disks, Incremental Scalable, Upto 2400 disks, Open Migrator/LM

2005-2006 – Symmetrix DMX-3 – Dynamic Cache Partitioning, Symmetrix Priority Controls, Virtual LUN Technology, Symmetrix Service Credential, Tamper Proof Audit Logs, Secure Data Eraser, RAID 6 Protections.

2007- 2008 Symmetrix DMX-4 – 4GB/s Point to point Backend, FC & SATA Intermix, RSA enVision Intergration, Flash Drives, Virtual Provisioning Cascaded SRDF.

There are two primary ways to reduce power consumption by carefully configuring the storage array itself and by taking advantage of EMC tools. Useful tips that will help to design an efficient DMX-3 array, including:

1) Minimizing DA pairs required.

2) Using more daisy chain storage bays to obtain needed capacity with fewer DA pairs.

3) Fully loading drive enclosures with drives (15) to reduce excess power overhead from cooling, logic, and power supply load efficiency.

4) Fully populating your DA pairs before adding additional pairs.

5) Ordering storage bays in increments of half to fully utilize enclosures.

6) Using larger capacity drives to reduce spindles.

7) Using tiered storage to reduce the number of higher speed drives when requirements allow.

8) Using RAID 5 or other as opposed to RAID 1 full mirroring.

9) Adding incremental storage bays and DA pairs as demand changes.

10) Using shorter loops for high performance drives, longer loops for lower performance drives.

There are other tools and techniques available as well, including:

11) Using Symmetrix Optimizer to balance performance and create opportunities for using larger capacity drives.Using Snaps instead of full volume copies to conserve space and use fewer drives.

Lets talk about SRDF feature in DMX for disaster recovery/remote replication/data migration. In today’s business environment it is imperative to have the necessary equipment and processes in place to meet stringent service-level requirements. Downtime is no longer an option. This means you may need to remotely replicate your business data to ensure availability. Remote data replication is the most challenging of all disaster recovery activities. Without the right solution it can be complex, error prone, labor intensive, and time consuming.

SDRF/S addresses these problems by maintaining real-time data mirrors of specified Symmetrix logical volumes. The implementation is a remote mirror, Symmetrix to Symmetrix.
¨ The most flexible synchronous solution in the industry
¨ Cost effective solution with native GigE connectivity
¨ Proven reliability
¨ Simultaneous operation with SRDF/A, SRDF/DM and/or SRDF/AR in the same system
¨ Dynamic, Non-disruptive mode change between SRDF/S and SRDF/A
¨ Concurrent SRDF/S and SRDF/A operations from the same source device
¨ A powerful component of SRDF/Star, multi-site continuous replication over distance with zero RPO service levels.
¨ Business resumption is now a matter of a systems restart. No transportation, restoration, or restoring from tape is required. And SRDF/S supports any environment that connects to a Symmetrix system – mainframe, open system, NT, AS4000, or Celerra.
¨ ESCON fiber, fiber channel, Gigabit Ethernet, T3, ATM, I/P, and Sonet rings are supported, providing choice and flexibility to meet specific service level requirements. SRDF/S can provide real-time disk mirrors across long distances without application performance degradation, along with reduced communication costs. System consistency is provided by ensuring that all related data volumes are handled identically – a feature unique to EMC. Hope this litte article will help you to understand about SRDF/S.

EMC Brings Flash Drives in DMX-4 Frame

I have attended EMC Live classroom for new series of symmetrix DMX-4. I thought to share depth new architectural knowledge to you all.

EMC made a important announcement with respect to its 73 GB and 146 GB flash drives or solid state drives (SSD). Flash Drives and SSD represent a new solid-state storage tier, “tier 0”, for symmetrix DMX-4. In addition to that EMC will offer Virtual Provisioning for Symmetrix 3 and 4 as well 1 TB SATA II drives.

With this announcement EMC became first storage vendor to integrate Flash Technology into its enterprise-class arrays. There as excitement in industry who is looking for faster transaction and performance. Why this much excitement for new customer? I will be discussing some technical stuff in coming paragraph.

With flash drive technology in a Symmetrix DMX-4 storage system, a credit card provider could clear up to six transactions in the time it once took to process a single transaction. Overall, EMC’s efforts could significantly alter the dynamics of the flash SSD market, where standalone flash storage systems have been available only from smaller vendors.

EMC said that the new flash drives will cost about 30 times what an equivalent size high speed FC drive, and estimated that adding four drives would raise the cost of a Symmetrix disk storage system by about 10%. But in high-end business applications where every bit of IOPS performance counts, that premium becomes entirely acceptable. When an organization truly needs a major boost then flash drives are a very real and very reasonable solution.

Now, let’s talk about technical specification:

# DMX-4 can support upto 128 Flash drives in a frame

# Flash dives manufactured by STEC,Inc

# DMX-4 uses RAID 5(3+1) and (7+1) for flash drives

# Flash drives will operate on a 2GB/s FC loop

# Flash drives have in two size 73 GB and 146 GB 3।5” FC drive form factor at 2GB/s

# Flash drives support both format FBA and CKD emulation

# Limitation: - All the members must be Flash drives within same quadrant। (DA pair)

# Must have at least one flash drive as a Hot Spare।

# RAID 1 and RAID 6 are also in qualification

# Mixing Flash & Disk drives on the same loop is allowed

# PowerVault drives must be hard disk drives

# Maximum 32 flash drives per DA

# Cache Partiioning and QOS priority control highly recommended

# Flash Drives cab be protected with TimeFinder and SRDF

Most Suitable for Customer like:

# Algorithmic Trading

# Currency Exchange & Arbitrage
# Trade Optimization

# Real Time Data/Feed Processing

# Credit Card Fraud Detection

# Contextual Web Advertising

# Real Time Transaction Systems

# Data Modeling & Analysis

One Flash drive can deliver IOPS equivalent to 30 15K hard disk drives with approximately 1 ms application response time. This means Flash memory achieves unprecedented performance and the lowest latency ever available in an enterprise-class storage array.