Its been a few months since my last post (read it here) about Hybrid Hard Disk Drive (HHDD) such as the Seagate Momentus XT that I have been using.


The Momentus XT HHDD I have been using is a 500GB 7,200RPM 2.5 inch SATA Hard Disk Drive (HDD) with 4GB of embedded FLASH (aka SSD) and 32MB of DRAM memory for buffering hence the hybrid name.



I have been using the XT HHDD mainly for transferring large multi GByte size files between computers and for doing some disk to disk (D2D) backups while becoming more comfortable with it. While not as fast as my 64GB all flash SSD, the XT HHDD is as fast as my 7,200RPM 160GB Momentus HDD and in some cases faster on burst reads or writes. The notion of having a 500GB HDD that was affordable to support D2D was attractive however the ability to get some performance boost now and then via the embedded 4GB FLASH opens many different possibilities particularly when combined with compression.



Recently I switched the role of the Momentus XT HHDD from that of being a utility drive to becoming the main disk in one of my laptops. Despite many forums or bulletin boards touting issues or problems with the Seagate Momentus XT causing system hangs or Windows Blue Screen of Death (BSoD), I continued on with the next phase of testing.



Making the switch to XT HHDD as a primary disk



I took a few precaution including eating some of my own dog food that I routinely talk about. For example, I made sure that the Lenovo T61 where the Momentus XT was going to be installed was backed up. In addition, I synced my traveling laptop so that it was the primary so that I could continue working during the conversion not to mention having an extra copy in addition to normal on and offsite backups.



Ok, lets get back to the conversion or migration from a regular HDD to the HHDD.



Once I knew I had a good backup, I used the Seagate Discwizard (e.g. Acronis based) tool for imaging the existing T61 HDD to the Momentus XT HHDD. Using Discwizard (you could use other tools as well) I configured it to initialize the HHDD which was attached via a Seagate Goflex USB to SATA cable kit as well as image or copy the contents of the T61 HDD partitions to the Momentus XT. During the several hours it took to copy and create a new bootable disk image on the HHDD I continued working on my travel or standby laptop.



After the image copy was completed and verified, it was time to reboot and see how Windows (XP SP3) liked the HHDD which all seemed to be normal. There were some parts of the boot that seemed a bit faster, however not 100 percent conclusive. The next step was to shutdown the laptop and physically swap the old internal HDD with the HHDD and reboot. The subsequent boot did seem faster and programs accessing large files also seemed to run a bit faster.



Keep in mind that the HHDD is still a spinning 7,200RPM disk drive so comparisons to a full time SSD would be apples to oranges as would the cost capacity difference between those devices. However, for what I wanted to see and use, the limited 4GB of flash does seem to provide a performance boost and if I needed full time super fast performance, I could buy a larger capacity SSD and install it. Im going to hold off on buying any more larger capacity flash SSD for the time being however.



Do I see HHDD appearing in SMB, SME or enterprise storage systems anytime soon? Probably not, at least not in primary storage systems. However perhaps in some D2D backup, archive or dedupe and VTL devices or other appliances.



Momentus XT Speed Bumps



Now, to be fair, there have been some bumps in the road!



The first couple of days were smooth sailing other than hearing the mystery chirp the HHDD makes a couple of times a day. Low and behold after a couple of days, just as many forums had indicated, a mystery system hang occurred (and no, not like Windows might normally do so for those Microsoft cynics). Other than the inconvenience of a reboot, no data was lost as files being updated were saved or had been backed up not to mention after the reboot, everything was intact anyway. So far just an inconvenience or so I thought.



Almost 24 hours later, same thing except this time I got to see the BSoD which candidly, I very rarely see despite hearing stories from others. Ok, this was annoying, however as long as I did not lose any data, other than lost time from a reboot, lets chalk this up to a learning experience and see where it goes. Now guess what, about 12 hours later, once again, the system froze up and this time I was in the middle of a document edit. This time I did lose about 8 minutes of typing data that had not been auto saved (I have since changed my auto save from 10 minutes to 5 minutes).



With this BSoD incident, I took some notes and using the X61s, started checking some web sites and verified the BIOS firmware on the T61 which was up to date. However I noticed that the Seagate Momentus XT HHDD was at firmware 22 while there was a 23 version available. Reading through some web sites and forums, I was on the fence on trying firmware 23 given that it appears a newer firmware version for the HHDD is in the works. Deciding to forge forward with the experiment, after all, no real data loss had occurred, and I still had the X61s not to mention the original T61 HDD to fall back to worse case.



Going to the Seagate web site, I downloaded the firmware 23 install kit and ran it to their instructions which was a breeze and then did the reboot.



It has not been quite a week yet, however knocking on wood, while I keep expecting to see one, no BSoD or system freezes have occurred. However having said that and knocking on wood, Im also making sure things are backed up protected and ready if needed. Likewise, if I start to see a rash of BSoD, my plan is to fall back to the original T61 HDD, bring it up to date and use it until a newer HHDD firmware version is available to resume testing.



What is next for my Seagate Momentus XT HHDD?



Im going to wait to see if the BSoD and mystery system hangs disappear as well as for the arrival of the new firmware followed by some more testing. However, when Im confident with it, the next step is to put the XT HHDD into the X61s which is used primarily for travel purpose.



Why wait? Simple, while I can tolerate a reboot or crash or data loss or disruption while in the office given access to copies as well as standby or backup systems to work from, when traveling options are more limited. Sure if there is data loss, I can go to my cloud provider and rapidly recall a file or multiple ones as needed or for critical data, recover from a portable encrypted USB device. Consequently I want more confidence in the XT HHDD before deploying it for travel mode which it is probably safe to do as of now, however I want to see how stable it is in the office before taking it on the road.



What does this all mean?



  • Simple, have a backup of your data and systems

  • Test and verify those backups or standby systems periodically

  • Have a fall back plan for when trying new things

  • Keep productivity in mind, at some point you may have to fall back

  • If something is important enough to protect, have multiple copies

  • Be ready to eat your own dog food or what you talk about

  • Do not be scared, however be prepared, look before you leap


How about you are you using a HHDD yet and if so, what are your experiences? I am curious to hear if anyone has tried using a HHDD in their VMware lab environments yet in place of a regular HDD or before spending a boat load of money for a similar sized SSD.


Nuff said for now



Cheers gs



Greg Schulz - Author The Green and Virtual Data Center (CRC) and Resilient Storage Networks (Elsevier)


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