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Another important factor to HDD performance is seek time, described as the time from when a read or 

write action is initiated until the data transfer from or to the disk actually begins. The smaller platters 

of SFF SAS drives inherently yield lower seek times, an advantage in file servers with frequent random 
accesses. 

SAS use for enterprise systems 

This section describes SAS design features that affect the performance and operating efficiency of 

SAS HDDs for enterprise-class systems. For a general discussion of SAS technology, refer to the HP 

white paper “Serial Attached SCSI Technology” available at the following HP web page: 

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00302340/c00302340.pdf

 

 

Since RAID strategies and AFR numbers favor high-density systems, SFF SAS drives are an attractive 

solution for large enterprise systems. Compared to 3.5-inch large form factor (LFF) SAS drives, 

2.5-inch SFF SAS drives have these advantages: 

•

 

Lower AFR 

•

 

15 to 20 percent higher Input/output Operations Per Second (IOPS) 

•

 

30 percent smaller physical size 

•

 

Up to half the power consumption 

Increasing HDD density in a RAID-based system invariably enhances the overall performance of the 
storage system. Increasing the drive density also expands the choice of RAID strategies as indicated in 

Table 2. 

Table 2. 

Comparison of drive support in two 1U HP ProLiant servers

 

Server 

DL320 G5 

DL360 G5 

Drive type 

LFF SAS [1] or SATA 

SFF SAS or SATA 

# of drives 

4 

6 

RAID support 

RAID 0, 1 [1] 

RAID 0, 1, 10, 5, 6 [2] 

NOTES: 
[1] Requires optional SAS controller  
[2] RAID 6 requires P400i with 512MB Battery Backed Write Cache option 
 

At the drive level, smaller/faster is usually better. SFF drives offer a spindle-per-U advantage that 

yields better performance in most systems.   
Traditionally, LFF drives have a cost-per-GB advantage over SFF types. For workstation and small-to-

medium business customers, getting the most storage capacity for the money is a key factor in setting 

up a system. For the enterprise IT architect, however, the goal should be to get the most work (that is, 

more IOPS) out of the system, and this is best achieved with high density storage systems. 

4 

Summary of Contents for 418371-B21 - Dual Port 72 GB Hard Drive

Page 1: ...parameters for enterprise environments 3 SAS use for enterprise systems 4 HDD performance comparisons 5 Performance comparison between SATA and SAS drives 5 Performance comparisons between SAS drives 8 Performance comparisons based on form factor 8 Performance comparisons based on platter speed 11 SAS drive specifications 13 Conclusion 13 For more information 14 Call to action 14 ...

Page 2: ...and Queuing NCQ allow controllers and compatible HDDs to take advantage of the read write head position for more efficient drive operations RAID is another logic based solution that places data in stripes across multiple drives to enhance reliability performance and data integrity A variety of RAID strategies1 are in use RAID 0 Striping to two or more disks no parity for performance improvement no...

Page 3: ...Key HDD design parameters for enterprise environments Enterprise class HDDs must provide maximum performance under a 100 percent duty cycle and continuous I O workload in a high vibration environment While Mean Time Before Failure MTBF is used to express the length of HDD life in general a more meaningful benchmark the Annual Failure Rate AFR better defines the estimated life of an HDD in the ente...

Page 4: ...percent higher Input output Operations Per Second IOPS 30 percent smaller physical size Up to half the power consumption Increasing HDD density in a RAID based system invariably enhances the overall performance of the storage system Increasing the drive density also expands the choice of RAID strategies as indicated in Table 2 Table 2 Comparison of drive support in two 1U HP ProLiant servers Serve...

Page 5: ...drives using the following configuration System HP StorageWorks 60 Modular Smart Array SAS Controller HP Smart Array P400 firmware version 4 12 512 MB cache RAID 1 Figure 1 Relative performance sequential operations of non NCQ SATA NCQ SATA and SAS 2 drive array with HP Smart Array P400 Controller RAID 1 Sequential Operations RAID 1 128 KB 0 100 200 300 400 500 600 700 800 900 1000 1 2 4 8 16 32 6...

Page 6: ...ANDOM READ 8KB RANDOM WRITE 8KB OLTP 64KB RANDOM READ 64KB RANDOM WRITE RELATIVE PERFORMANCE IOMETER 07 30 2004 SATA Non NCQ 60 GB 5 4K 25 75 R W cache baseline performance level SATA NCQ 120 GB 5 4K 25 75 R W cache SAS 72 GB 15K 25 75 R W cache The HP P400 controller supports NCQ so the NCQ SATA drives provide an increase in performance over non NCQ SATA drives The SAS arrays however are much fas...

Page 7: ...6 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 4KB RANDOM READ 4KB RANDOM WRITE 4KB OLTP 8KB RANDOM READ 8KB RANDOM WRITE 8KB OLTP 64KB RANDOM READ 64KB RANDOM WRITE THROUGHPUT IOPS IOMETER 07 30 2004 SATA Non NCQ 60 GB 5 4K 25 75 R W cache SATA NCQ 120 GB 5 4K 25 75 R ...

Page 8: ...ntroller RAID 0 128K RAID 0 128KB 70 80 90 100 110 120 130 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 4KB RANDOM READ 4KB RANDOM WRITE 4KB OLTP 8KB RANDOM READ 8KB RANDOM WRITE 8KB OLTP 64KB RANDOM READ 64KB RANDOM WRITE Diff SFF 15K Performan...

Page 9: ...6 32 64 128 256 4KB RANDOM READ 4KB RANDOM WRITE 4KB OLTP 8KB RANDOM READ 8KB RANDOM WRITE 8KB OLTP 64KB RANDOM READ 64KB RANDOM WRITE Diff SFF 15K Performance compared to LFF 15K IOMETER 07 30 2004 Level of performance for LFF SAS drives 2 SFF SAS drives 4 SFF SAS rives 6 SFF SAS drives 8 SFF SAS drives 12 SFF SAS drives RAID 1 is a strategy for achieving redundancy rather than enhanced performan...

Page 10: ... 3000 3500 4000 4500 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 1 2 4 8 16 32 64 128 256 4KB RANDOM READ 4KB RANDOM WRITE 4KB OLTP 8KB RANDOM READ 8KB RANDOM WRITE 8KB OLTP 64KB RANDOM READ 64KB RANDOM WRITE THROUGHPUT IO Per Second IOMETER 07 30 2004 4 SFF SAS drives...

Page 11: ...ise server environment a large number of users generating requests can result in a queue depth of tens or hundreds Chart 7F shows random read IOPS performance Figure 7 Performance comparison 10K versus 15K RPM RAID 5 controller and 6 SFF SAS drives A Sequential read Q1 B Sequential read Q4 C Sequential read Q8 D Sequential read Q16 E Sequential read Q32 F Random IOPS 10K RPM SAS HDD 15K RPM SAS HD...

Page 12: ...er random read IOPS than 10K drive arrays Also overall performance scales with array size number of drives Note that performance is best when retrieving data blocks that are larger than the RAID 5 stripe size 128 KB in this case For optimum performance the stripe size should be configured for the specific application 2500 2000 1500 1000 500 IOPS No of drives 10K HDD P400 controller 15K HDD 6402 co...

Page 13: ...atts 8 73 watts NOTE All drives listed In Table 3 have a cache buffer size of 16 MB and a transfer time of 3 Gb s Conclusion A variety of hard drive types are used in today s server industry The right HDD type is the one that provides the best return on investment ROI for a particular server application Small to medium businesses SMBs or environments with less than demanding applications can be we...

Page 14: ...ief http h20000 www2 hp com bc docs support SupportManual c0 0302340 c00302340 pdf Call to action Send comments about this paper to TechCom HP com 2008 Hewlett Packard Development Company L P The information contained herein is subject to change without notice The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services N...

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