Seagate ST1000DX002 1TB hybrid drive speed issue

[tremolux]

I have a Dell desktop PC with a Seagate 1TB 7200 RPM hybrid drive (ST1000DX002) that is giving me strange speed problems - it's incredibly slow on a particular task.

Configuration

• 
  ■ PC Model: Dell Optiplex 7010
  ■ Windows 7 Pro SP1 w/all updates
  ■ Processor: i7-3770 (4-core/8-logical @ 3.40 GHz)
  ■ RAM: 16GB
  ■ SATA: Intel 7 Series/C216 Chipset SATA AHCI Controller
  ■ Display: AMD Radeon HD 7570
  ■ Optical disc: MATSHITA DVD+-RW ATA (internal)
  ■ Optical disc: LG BD-RE BE14NU40 USB Blu-ray/DVD (external)

Problem
A task that utilizes parallel processing is running extremely slowly compared to other systems we run it on. On a larger system (24-core/48-logical, 32GB, faster disk) it takes about 6-7 minutes to process 1205 files, but on the Dell it takes 8 hours.

The overall task takes all the files in one directory tree, does a transformation (balanced between CPU- and I/O-intensive), and stores the corresponding output files in a second directory tree. Each parallel instance processes 1 subdirectory of the root, with an additional instance to handle the root directory itself. The number of simultaneous instances depends on the number of logical processors; on the large system, up to 24 instances can run at once, while on the Dell up to 8 instances can run. The same data is being processed in both cases: 1205 files in 158 directories.

Note: On the Dell, the input data has been read from the Blu-ray drive and written to the disk drive, so at least some of the file contents might still be in OS buffers; not sure if Windows 7 does read-ahead from the disk.

Observations

■ Clearly the large system is going to perform better, but I think it unlikely that it's 80 times faster; I would expect on the order of 5-10 times faster (which suggests perhaps 30-60 minutes on the Dell)
■ The raw transfer rate (read) of the ST1000DX002 ranges between 100 and 200 MB/sec as measured by HD Tune Pro, while the disk on the large system has a transfer rate of about 150-250 MB/sec (also HD Tune Pro)
■ The large system keeps 40-50% of the processors busy - limited to 24 instances - @ 2.2 GHz, but the Dell's processors are nearly idle (about 3% total CPU utilization)
■ Despite the raw speed, the ST1000DX002 transfer rate from Resource Monitor is only 1-3 MB/sec during the parallel task; on the large system the transfer rate is about 60-80 MB/sec during processing
■ On the large system, about 30-50% of the available memory is in use; on the Dell, less than 5% is in use

My Conclusion (so far)
The Dell is waiting on the hybrid drive. I'm thinking that if the drive were defective, the raw speed benchmark would be much worse (but I could be mistaken).

Any ideas/pointers?

 

[Lutfij]

Hybrid drives have a small capacity SSD onboard paired with a large HDD capacity and the SSD comes into play when you are using the HDD as a primary drive with some frequently used programs/apps. If you're using that particular drive for data transfer then you should either go for an all SSD layout. On the info pertaining the system waiting on the hybrid drive, you are right since the SSD that is paired into such devices aren't the best in class which explains how you're able to get them at an affordable price when you compare a 250GB SSD being priced the same.

 

[tremolux]

Hybrid drives have a small capacity SSD onboard paired with a large HDD capacity and the SSD comes into play when you are using the HDD as a primary drive with some frequently used programs/apps. If you're using that particular drive for data transfer then you should either go for an all SSD layout. On the info pertaining the system waiting on the hybrid drive, you are right since the SSD that is paired into such devices aren't the best in class which explains how you're able to get them at an affordable price when you compare a 250GB SSD being priced the same.

Thanks for the info. The speed reduction seems pretty drastic.

I'm curious as to why the read benchmark showed a good transfer rate, but the real-world read/write performance is much worse; does reading the entire drive somehow bypass the SSD or render it inoperative? [I would've run a write benchmark but that required overwriting the drive. ] Also, I would expect the read/write performance to more nearly reflect the HD speed if the SSD isn't caching much of anything.

 

[tremolux]

Further performance experimentation showed that the primary culprit responsible for the slow hybrid disk speed was McAfee enterprise encryption. We were troubleshooting a similar performance problem on a different small machine (laptop w/dual-core i5, 8 GB RAM, 500 GB HD) when we discovered the encryption issue. The task we were performing was taking 1.5-2.0 hours but when we disabled encryption it dropped to 1 minute(!).

So I went back to the Dell and made 2 changes:

■ Put the hybrid drive on its own SATA PCIe host adapter (6.0 Gb/sec)
■ Had the parallel-processing task write its output to an unencrypted directory

The 8 hour task took 33 minutes after these changes, about what I would have expected. The data transfer rate went from 1-3 MB/sec to about 40 MB/sec (range roughly 30-50 MB/sec). The CPU and memory had low utilization, so I'll consider increasing the max number of parallel instances, but the queue length for the hybrid drive was noticeably higher than we usually see, so running more instances at once might not improve performance.

As suggested, an SSD or fast HD would probably be better than the SSHD, but at least the hybrid drive is not a total loss.