Monday, June 20, 2011

Intel's 720-series SSDs

Intel's new 720-series SSDs are extremely fast, equally expensive, not yet available, and you can't stick one in a laptop. Stop reading now before it gets worse.

A prototype PCIe SSD Intel demoed in 2009
(The product will only slightly resemble the photo on the right that depicts a prototype Intel demoed in 2009.)

Speed.  Intel 720 Series "Ramsdale" SSDs are rumored to have 2.2GB/s read and 1.8GB/s write speeds. That's Gigabytes, not Gigabits - and represents about a 500% to 1000% speed improvement over current SSDs, not to mention being about 15 times faster than regular spinning disks. The device will easily play or record several uncompressed 4K video streams simultaneously and do many other things that previously required a humongous and energy hungry storage array.

Why do I need one.  The kicker isn't the raw speed or extremely low latencies - it's the compactness of it, and the relatively low buy-in.  Before this and similar devices became available, the only way to achieve such performance was a storage box with at least 24 mechanical hard drives or 8+ SSDs with a RAID controller, connected to the host computer via super-fast multi-link SAS or Fibre Channel connections.  The buy-in is usually north of $10K, often $20K for an enterprise-class solution.  Granted, you get a lot more Terabytes with those - however if it's portability and speed you are after vs. raw capacity - this device will likely be calling your name.

Where do I put it?  As there isn't yet a cable connection fast enough to accommodate such speeds - not even Thunderbolt (aka LighPeak) - the only connection offered is 8-lane PCI Express.  Thus, it won't fit inside a laptop, other than externally via a PCIe expander from Magma or JMR.

Prices.  If current SLC SSD prices of over $10 per gigabyte are any indication, a 200GB version should start at over $2000. It may however boot your PC in a scant few seconds undoubtedly motivating some gamers to spring for their wallets.

Real-world applications: ultra-hi-res (like, uncompressed 4K), multi-stream and ultra high speed field video acquisition and monitoring, enterprise data caching and yes, definitely probably some gamers.

Exciting times we live in.

Thursday, April 21, 2011

No desktop drives in RAID?

WD Black Caviar
Some of the fastest and well rated large capacity desktop drives are WD Black Caviars. They also 50%-100% less expensive than their "enterprise class" RE4 series siblings. Can you use them in RAIDs? Western Digital says "no" in their spec sheet:
  • "Desktop / Consumer RAID Environments - WD Caviar Black Hard Drives are tested and recommended for use in consumer-type RAID applications (RAID-0 / RAID-1).
  • "Business Critical RAID Environments – WD Caviar Black Hard Drives are not recommended for and are not warranted for use in RAID environments utilizing Enterprise HBAs and/or expanders and in multi-bay chassis, as they are not designed for, nor tested in, these specific types of RAID applications. For all Business Critical RAID applications, please consider WD’s Enterprise Hard Drives that are specifically designed with RAID-specific, time-limited error recovery (TLER), are tested extensively in 24x7 RAID applications, and include features like enhanced RAFF technology and thermal extended burn-in testing."
Also in their KB article:
"Western Digital manufactures desktop edition hard drives and RAID Edition hard drives. Each type of hard drive is designed to work specifically as a stand-alone drive, or in a multi-drive RAID environment."
There is more detailed information in that KB article:

"When an error is found on a desktop edition hard drive, the drive will enter into a deep recovery cycle to attempt to repair the error, recover the data from the problematic area, and then reallocate a dedicated area to replace the problematic area. This process can take up to 2 minutes depending on the severity of the issue. Most RAID controllers allow a very short amount of time for a hard drive to recover from an error. If a hard drive takes too long to complete this process, the drive will be dropped from the RAID array. Most RAID controllers allow from 7 to 15 seconds for error recovery before dropping a hard drive from an array. Western Digital does not recommend installing desktop edition hard drives in an enterprise environment (on a RAID controller).
"Western Digital RAID edition hard drives have a feature called TLER (Time Limited Error Recovery) which stops the hard drive from entering into a deep recovery cycle. The hard drive will only spend 7 seconds to attempt to recover. This means that the hard drive will not be dropped from a RAID array. While TLER is designed for RAID environments, a drive with TLER enabled will work with no performance decrease when used in non-RAID environments."
In other words, WD is OK with Black Caviars for home and gaming use in RAID0 and 1, and is not OK with using them in external enclosures - even in RAID0.

Compare that to Deskstar 7K3000 desktop hard drives whose maker Hitachi says they are suitable for:
  1. "Consumer and commercial computers"
  2. "Video editing arrays"
...with no explicit warnings against commercial or enterprise class RAID configurations.

Bottom line, Hitachi supports their desktop drives in high performance arrays while WD doesn't.

What is your experience with using desktop drives in RAIDs?

Friday, January 28, 2011

Quick Disk Benchmark in Windows

If you need to quickly test disk performance of an individual drive in Windows Vista and 7 without downloading any 3rd party tools, use Windows System Assessment Tool (WinSAT) from an administrative command prompt, in the following format:

winsat disk -drive C:

Substitute "C:" with the drive letter you'd like to test. To run command prompt in administrative mode, click "Start", type "cmd" in the search box, wait till "cmd.exe" shows up in the results, right-click on it, click on "run as administrator":

A command prompt box will open:

Type: winsat disk -drive C:

Substitute "C:" with the drive letter you'd like to test; press "Enter".

The command will run a minute or two. Here is what the results will look like:

Highlighted are numbers that are most important: read and write transfer rates.

There might be a million of reasons why you may need to know your individual drives' transfer rates:
  • copying from one drive to another takes a long time, and you'd like to know which one is especially slow
  • monitoring system health
  • finding out if your drives are fast enough for a specific task, e.g. capture and playback uncompressed video.
There are also other tools for testing drive speeds, from benchmark software vendors and hardware manufacturers such as BlackMagic Design and AJA. WinSAT however is already included in a standard Windows installation and may be just the right tool to quickly assess disk transfer rates.

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