Enterprise SSHD and Flash SSD Part of an Enterprise Tiered Storage Strategy

April 24, 2014 – 8:56 pm
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Enterprise SSHD and Flash SSD Part of an Enterprise Tiered Storage Strategy

The question to ask yourself is not if flash Solid State Device (SSD) technologies are in your future.

Instead the questions are when, where, using what, how to configure and related themes. SSD including traditional DRAM and NAND flash-based technologies are like real estate where location matters; however, there are different types of properties to meet various needs. This means leveraging different types of NAND flash SSD technologies in different locations in a complementary and cooperative aka hybrid way.

Introducing Solid State Hybrid Drives (SSHD)

Solid State Hybrid Disks (SSHD) are the successors to previous generation Hybrid Hard Disk Drives (HHDD) that I have used for several years (you can read more about them here, and here).

While it would be nice to simply have SSD for everything, there are also economic budget realities to be dealt with. Keep in mind that a bit of nand flash SSD cache in the right location for a given purpose can go a long way which is the case with SSHDs. This is also why in many environments today there is a mix of SSD, HDD of various makes, types, speeds and capacities (e.g. different tiers) to support diverse application needs (e.g. not everything in the data center is the same).

However, If you have the need for speed and can afford or benefit from the increased productivity by all means go SSD!

Otoh if you have budget constraints and need more space capacity yet want some performance boost, then SSHDs are an option. The big difference however between today’s SSHDs that are available for both enterprise class storage systems and servers, as well as desktop environments is that they can accelerate both reads and writes. This is different from their predecessors that I have used for several years now that had basic read acceleration, however no write optimizations.

SSHD storage I/O oppourtunity
Better Together: Where SSHDs fit in an enterprise tiered storage environment with SSD and HDDs

As their names imply, they are a hybrid between a nand flash Solid State Device (SSD) and traditional Hard Disk Drive (HDD) meaning a best of situation. This means that the SSHD are based on a traditional spinning HDD (various models with different speeds, space capacity, interfaces) along with DRAM (which is found on most modern HDDs), along with nand flash for read cache, and some extra nonvolatile memory for persistent write cache combined with a bit of software defined storage performance optimization algorithms.

Btw, if you were paying attention to that last sentence you would have picked up on something about nonvolatile memory being used for persistent write cache which should prompt the question would that help with nand flash write endurance? Yup.

Where and when to use SSHD?

In the StorageIO Industry Trends Perspective thought leadership white paper I recently released compliments of Seagate Enterprise Turbo SSHD (that’s a disclosure btw ;) enterprise class Solid State Hybrid Drives (SSHD) were looked at and test driven in the StorageIO Labs with various application workloads. These activities include being in a virtual environment for common applications including database and email messaging using industry standard benchmark workloads (e.g. TPC-B and TPC-E for database, JetStress for Exchange).

Storage I/O sshd white paper

Conventional storage system focused workloads using iometer, iorate and vdbench were also run in the StorageIO Labs to set up baseline reads, writes, random, sequential, small and large I/O size with IOPs, bandwidth and response time latency results. Some of those results can be found here (Part II: How many IOPS can a HDD, HHDD or SSD do with VMware?) with other ongoing workloads continuing in different configurations. The various test drive proof points were done in the   comparing SSHD, SSD and different HDDs.

Data Protection (Archiving, Backup, BC, DR)

Staging cache buffer area for snapshots, replication or current copies before streaming to other storage tier using fast read/write capabilities. Meta data, index and catalogs benefit from fast reads and writes for faster protection.

Big Data DSS
Data Warehouse

Support sequential read-ahead operations and “hot-band” data caching in a cost-effective way using SSHD vs. slower similar capacity size HDDs for Data warehouse, DSS and other analytic environments.

Email, Text and Voice Messaging

Microsoft Exchange and other email journals, mailbox or object repositories can leverage faster read and write I/Os with more space capacity.

OLTP, Database
 Key Value Stores SQL and NoSQL

Eliminate the need to short stroke HDDs to gain performance, offer more space capacity and IOP performance per device for tables, logs, journals, import/export and scratch, temporary ephemeral storage. Leverage random and sequential read acceleration to compliment server-side SSD-based read and write-thru caching. Utilize fast magnetic media for persistent data reducing wear and tear on more costly flash SSD storage devices.

Server Virtualization

Fast disk storage for data stores and virtual disks supporting VMware vSphere/ESXi, Microsoft Hyper-V, KVM, Xen and others.  Holding virtual machines such as VMware VMDKs, along with Hyper-V and other hypervisor virtual disks.  Compliment virtual server read cache and I/O optimization using SSD as a cache with writes going to fast SSHD. For example VMware V5.5 Virtual SAN host disk groups use SSD as a read cache and can use SSHD as the magnetic disk for storing data while boosting performance without breaking the budget or adding complexity.

Speaking of Virtual, as mentioned the various proof points were run using Windows systems that were VMware guests with the SSHD and other devices being Raw Device Mapped (RDM) SAS and SATA attached, read how to do that here.

Hint: If you know about the VMware trick for making a HDD look like a SSD to vSphere/ESXi (refer to here and here) think outside the virtual box for a moment on some things you could do with SSHD in a VSAN environment among other things, for now, just sayin ;).

Virtual Desktop Infrastructure (VDI)

SSHD can be used as high performance magnetic disk for storing linked clone images, applications and data. Leverage fast read to support read ahead or pre-fetch to compliment SSD based read cache solutions. Utilize fast writes to quickly store data enabling SSD-based read or write-thru cache solutions to be more effective. Reduce impact of boot, shutdown, and virus scan or maintenance storms while providing more space capacity.

Table 1 Example application and workload scenarios benefiting from SSHDs

Test drive application proof points

Various workloads were run using Seagate Enterprise Turbo SSHD in the StorageIO lab environment across different real world like application workload scenarios. These include general storage I/O performance characteristics profiling (e.g. reads, writes, random, sequential or various IOP size) to understand how these devices compare to other HDD, HHDD and SSD storage devices in terms of IOPS, bandwidth and response time (latency). In addition to basic storage I/O profiling, the Enterprise Turbo SSHD was also used with various SQL database workloads including Transaction Processing Council (TPC); along with VMware server virtualization among others use case scenarios.

Note that in the following workload proof points a single drive was used meaning that using more drives in a server or storage system should yield better performance. This also means scaling would be bound by the constraints of a given configuration, server or storage system. These were also conducted using 6Gbps SAS with PCIe Gen 2 based servers and ongoing testing is confirming even better results with 12Gbs SAS, faster servers with PCIe Gen 3.

SSHD large file storage i/o
Copy (read and write) 80GB and 220GB file copies (time to copy entire file)

SSHD storage I/O TPCB Database performance
SQLserver TPC-B batch database updates

Test configuration: 600GB 2.5” Enterprise Turbo SSHD (ST600MX) 6 Gbps SAS, 600GB 2.5” Enterprise Enhanced 15K V4 (15K RPM) HDD (ST600MP) with 6 Gbps SAS, 500GB 3.5” 7.2K RPM HDD 3 Gbps SATA, 1TB 3.5” 7.2K RPM HDD 3 Gbps SATA. Workload generator and virtual clients ran on Windows 7 Ultimate. Microsoft SQL Server 2012 Database was on Windows 7 Ultimate SP1 (64 bit) 14 GB DRAM, Dual CPU (Intel x3490 2.93 GHz)), with LSI 9211 6Gbps SAS adapters with TPC-B (www.tpc.org) workloads. VM resided on separate data store from devices being tested. All devices being tested with SQL MDF were Raw Device Mapped (RDM) independent persistent with database log file (LDF) on a separate SSD device also persistent (no delayed writes). Tests were performed in StorageIO Lab facilities by StorageIO personal.

SSHD storage I/O TPCE Database performance
SQLserver TPC-E transactional workload

Test configuration: 600GB 2.5” Enterprise Turbo SSHD (ST600MX) 6 Gbps SAS, 600GB 2.5” Enterprise Enhanced 15K V4 (15K RPM) HDD (ST600MP) with 6 Gbps SAS, 300GB 2.5” Savio 10K RPM HDD 6 Gbps SAS, 1TB 3.5” 7.2K RPM HDD 6 Gbps SATA. Workload generator and virtual clients Windows 7 Ultimate. Microsoft SQL Server 2012 database was on Windows 7 Ultimate SP1 (64 bit) 14 GB DRAM, Dual CPU (E8400 2.99GHz), with LSI 9211 6Gbps SAS adapters with TPC-E (www.tpc.org) workloads. VM resided on separate SSD based data store from devices being tested (e.g., where MDF resided). All devices being tested were Raw Device Mapped (RDM) independent persistent with database log file on a separate SSD device also persistent (no delayed writes). Tests were performed in StorageIO Lab facilities by StorageIO personal.

SSHD storage I/O Exchange performance
Microsoft Exchange workload

Test configuration: 2.5” Seagate 600 Pro 120GB (ST120FP0021 ) SSD 6 Gbps SATA, 600GB 2.5” Enterprise Turbo SSHD (ST600MX) 6 Gbps SAS, 600GB 2.5” Enterprise Enhanced 15K V4 (15K RPM) HDD (ST600MP) with 6 Gbps SAS, 2.5” Savio 146GB HDD 6 Gbps SAS, 3.5” Barracuda 500GB 7.2K RPM HDD 3 Gbps SATA. Email server hosted as guest on VMware vSphere/ESXi V5.5, Microsoft Small Business Server (SBS) 2011 Service Pack 1 64 bit, 8GB DRAM, One CPU (Intel X3490 2.93 GHz) LSI 9211 6 Gbps SAS adapter, JetStress 2010 (no other active workload during test intervals). All devices being tested were Raw Device Mapped (RDM) where EDB resided. VM on a SSD based separate data store than devices being tested. Log file IOPs were handled via a separate SSD device.

Read more about the above proof points along view data points and configuration information in the associated white paper found here (no registration required).

What this all means

Similar to flash-based SSD technologies the question is not if, rather when, where, why and how to deploy hybrid solutions such as SSHDs. If your applications and data infrastructures environment have the need for storage I/O speed without loss of space capacity and breaking your budget, SSD enabled devices like the Seagate Enterprise Turbo 600GB SSHD are in your future. You can learn more about enterprise class SSHD such as those from Seagate by visiting this link here.

Watch for extra workload proof points being performed including with 12Gbps SAS and faster servers using PCIe Gen 3.

Ok, nuff said.


Greg Schulz – Author Cloud and Virtual Data Storage Networking (CRC Press), The Green and Virtual Data Center (CRC Press) and Resilient Storage Networks (Elsevier)
twitter @storageio

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