Testing your Network Attached Storage (NAS) Disks

If you have a NAS box which contains removable Hard Disk drives, you can test them outside of the NAS box. For example, the Netgear ReadyNAS NVX will house up to four drives. The basic NVX has two 500 GB drives and these are setup by default to the Netgear XRAID-2 standard. You get SMART information about the drives (for example the disk temperature and how many sectors on the disk have been reallocated because of read/write problems).

If your NAS box informs you that some SMART attribute has changed (it will do this either when you log onto the Admin page via your web Browser or it will send you an Email message), you can query the SMART data from the Browser, but this is usually not sufficient information if the drive in question is under warranty.

So what can you do?
You can run the manufacturer's test tool (in the case of Seagate this will be SeaTools for DOS or Windows. The latter is easier to use. Other manufacturers have their own tools). These tools are fine if your drive is attached via a SATA or eSATA connector, but if the drive is in a NAS box, the box will usually have an Ethernet connection. So you will have to remove the drive from the NAS box and connect it via a SATA or eSATA connection. A standalone PC might have such a connection available (if it was recently purchased), but a Notebook might not (it depends on its age and what it cost to purchase). In this case you will have to buy or loan a Hard Disk enclosure that can be attached to a Notebook card (Expresscard or Cardbus) which has an eSATA port. You cannot use the enclosure USB connection because USB does not support SMART data by default. What follows is a description of what needs to be done to get SMART data from your drive using a hard disk enclosure and an eSATA card on a Notebook PC.

What you need to do to get SMART data
Remove the specific drive from the NAS box (power it off first, you don't want the box to think a hot swap has taken place). The drive will be mounted on a carrier and attached by screws. You should ensure that any work you carry out on the drive is done on a dust free surface which is not prone to static and that you feel confident in carrying out the steps which follow.

You will need the following:

1. A Hard Disk enclosure which will accept a 3.5 inch drive. The enclosure needs to be able to operate with USB pass through over the USB Bridge that interfaces the drive to a PC connection. What this means is that SMART data can be queried by the PC from the enclosure interface and that this data will be returned. The problem with USB generally is that this data cannot be queried using the generic PC driver that supports a mass storage device. So make sure that your enclosure has BOTH USB and eSATA connections.
   
   A guide to which disk enclosures can support USB pass through is available here. The information on this page was gained by using an Icy Box IB-318StUS2-B disk enclosure.
2. A PC with an eSATA connection. On notebooks, this will be one of the connections around the periphery of the notebook. On a standard PC with a separate keyboard and monitor, the connection will either be at the back of the main box or inside the box. Many notebooks today still don't have eSATA connections, but you might have an ExpressCard or an older Cardbus PCMCIA socket. In either case, you need to find or purchase an eSATA card that will slide and lock into the socket. The information on this page was gained by using a StarTech 2 port Cardbus CBESAT2 card. The card comes with a CD-ROM which is used to install the driver (in this case a Silicon Image Sil 3512 SATALink controller driver.
3. A set of precision screwdrivers used for technical work (search on Amazon, for example, for DIY & Tools or Electronics & Photo departments and Precision Screwdriver. You need a 2.9 mm cross head screwdriver (think of a Philips or Posidrive screwdriver but smaller) to remove and fit the screw holding the inside mounting of the enclosure (e.g. the Icy Box), and to remove and fit the screws holding the drive in the NAS mounting and the drive in the enclosure. The enclosure should come with these screws.

The steps to follow are:

1. With the NAS powered OFF, open the front and remove the drive you want to test.
2. Undo the screw at the bottom of the enclosure (if present) and push from the front panel. The internal carrier for the hard drive should slide out.
3. On a dust free, non static surface (and you might want a grounding cable attaching you to the ground if you want to be absolutely safe), place the drive with the carrier plate upwards so you can see the screws.
4. Raise the carrier slightly at the handle end and gently place your fingers to support the edges of the drive. The sensitive areas of the drive (the electronic board and the spindle housing) are up against the carrier plate so your fingers only touch the metal underside of the drive. If you don't provide some support, you might damage the connection between the drive and the carrier socket.
   
   Undo the screws. I use the order of removal as: top left, bottom right, top right, bottom left. This helps to alleviate stresses. Now you can gently pull the drive from the carrier handle end and it should slip out from the connection.
5. Hold the drive gently by the long edges. DON'T TOUCH the side with the electronics board. Now ensure that the enclosure carrier is vertical and slip the drive in so that the drive and carrier connections are lined up and then gently push the drive into the carrier socket. You will notice that the top and bottom of the carrier each have two elongated slots. Screw holes on the sides of the drive are aligned with these slots. The enclosure should have a set of screws. These will be longer than the ones used by the NAS carrier. Screw two of them into the disk holes visible through the enclosure slots. Turn the enclosure carrier over and repeat with the other two screws.
6. Ensure the enclosure carrier is the right way up so that its securing screw hole is alinged with the enclosure casing. Slide the carrier into the casing and then tighten the screw.
7. If the enclosure has a base, fix the enclosure to it.
8. Fit any Expresscard or Cardbus to the PC (please ensure that any driver has been correctly installed).
9. Connect the eSATA port on the enclosure to the eSATA port on the PC using the enclosure eSATA cable (Its the flat cable, not the round USB cable).
10. Ensure that the enclosure power switch if OFF (if it has one).
11. Plug the enclosure power supply (usually a rat tail plug) into a switched off mains socket, and the low voltage plug into the enclosure socket.
12. Switch on the main power.
13. Switch ON the enclosure power switch (if it has one).
14. The drive in the enclosure should power up and the PC should indicate that it has found the drive.
15. If you click on the Plug and Play icon in the PC Taskbar area, you should see a popup menu with an item for the enclosure. It should indicate that it is a SATA controller. Just click outside of the menu to hide it.

To replace the drive into the NAS box from the hard disk enclosure, reverse the steps above, but FIRST click on the plug and play icon in the Taskbar area. When the menu pops up, select the item for the drive and click it. Windows will then inform you when it is SAFE to remove the eSATA cable from the PC. DON'T switch off the power to the hard disk enclosure before doing this step because the drive might still be powered up and you will probably get a head crash on the disk platter(s) (even though manufacturers provide a way of bringing a disk head to a stop without damaging the recording surface).

Now you are ready to get some SMART data. You can use one of the following methods:

1. Use commercial software that reports SMART data. Hard Disk Sentinel and SmartMonTools are two such examples.
2. Use Windows Management Instrumentation (WMI) to query the SMART classes:
   
   
   1. MSStorageDriver_ATAPISmartData
   2. MSStorageDriver_FailurePredictThresholds
   3. MSStorageDriver_FailurePredictStatus
3. Use a low level programming interface on the PC to access the data. Before WMI this was the only way to access SMART data.

In Item 2. above, A. will give you the SMART data associated with any recognized mass storage device, assuming that USB pass through is in operation for non-IDE hard disk drives (those not part of the original hardware). In B. above, the data returned contains the Threshold for each SMART attribute (usually the SMART attribute data is higher than the corresponding Threshold if the drive is operating normally). In C. above, there is a PredictFailure attribute which is either TRUE or FALSE. In normal operation, you would expect FALSE for this attribute.

The rest of this page assumes that you will use the VBScript files listed below to access the WMI SMART data (note that they are named XXX.vbs.txt so that you cannot inadvertantly run them without renaming them to remove the .txt at the end of the filename):

1. For ATAPISmartData right click on this link and then select Save Target As... from the popup menu. Then click the Save button on the Save As window to save the file to your PC.
2. For FailurePredictThresholds right click on this link and repeat as in 1. above.
3. For FailurePredictStatus right click on this link and repeat as in 1. above.

To keep you safe, you might want to review how to calculate and compare File Checksums to ensure that downloaded files have not been maliciously changed. For these txt files, you can use the AllIncVerifyCheckSum.exe program.

To use one of the above files as a script, rename it to remove the .txt from the end of the filename. You will then have a .VBS file which you can run (assuming that scripting is enabled on your PC). Each script produces an output text file (so atapismartdata.vbs produces the file atapismartdata.txt) which tells you all you need to know about the hard disk drives on, or attached, to your PC.

In the atapismartdata.txt and failurepredictthresholds.txt files the VendorSpecific line is the key item. It shows a sequence of values (0-9, A-F) separated by vertical bars. The format of the line is:

• The first two values, for example 16|0 represent version information. These can be ignored.
• There then follow one or more groups of twelve values which are the SMART attributes for a specific drive.
• Each group is arranged as follows:
  
  
  1. The first value is the ID of the attribute.
  2. The second and third values are the attribute status and are given in least then most significant order. Since the third value is probably 0, the ordering does not really matter. If the first value (entered as a Decimal value) is then displayed in a Calculator in Binary format you will get a sequence of 1's and 0's. This tells you what status bits apply to the attribute:
     
     
     • 000001 - Pre Failure Warranty.
     • 000010 - On Line Collection.
     • 000100 - Performance Attribute.
     • 001000 - Error Rate Attribute.
     • 010000 - Event Count Attribute.
     • 100000 - Self Preserving Attribute.
     So wherever you see a 1 in the corresponding position above, that status bit applies to the current SMART attribute. Probably the most important for a disk drive is the Pre Failure Warranty status bit. This means that you should be able to get a replacement drive if it fails while under warranty. You can usually check the warranty of your drive on the drive manufacturer's web site. There is usually a page on which you can enter the disk serial number and carry out a search of the manufacturer's database to find the warranty date. Most drives carry a five year warranty, BUT you might find that even a recently purchased disk does not have a full five year warranty because the disk was manufactured to stock and has been sitting in a warehouse somewhere for months. You can usually find the serial number of the drive if you access your NAS drive using the Browser Admin web page and look for the relevant SMART data associated with the specific drive.
  3. The fourth value is the Current Normalized Value for the attribute. For attribute 5 (Reallocated Sectors Count), this value decreases from 100 as the number of Reallocated Sectors increases. These are the sectors on the disk which have been mapped to a spare sector and the original sector has been marked as unusable for reading and writing data. This is an indication of potential disk failure in the future, but only if this value drops below the threshold value. Unfortunately, there is no absolute standard amongst drive manufacturers as to what this value really indicates.
  4. The fifth value is the Worst value for the attribute.
  5. The next six values are the Raw data for the attribute. For attribute 5, the first of these is the actual number of Reallocated Sectors in decimal. This is the value that your NAS will report to you.
  6. The last value is Reserved.

If attribute 5 above increases steadily over time, you should take steps to back up data (even on a NAS RAID unit) and run the disk manufacturer's Test Tool. For example, Seagate provides SeaTools for Windows and Dos which allow you to test various aspects of your disk drive (both Seagate drives and other manufacturers). The Windows version is probably the simplest one to use.

In the failurepredictthresholds.txt file, the layout of the VendorSpecific data is the same as above. After the attribute ID value is the Threshold value. This should be lower than than the Current Normalized Value of the specific attribute.

In the failurepredictstatus.txt file, the relevant item is Predict Failure. This should be FALSE if the drive is OK.

What happens when you run the Manufacturer's test tool?
The tool will probably recognise your drive in its hard disk enclosure and you can carry out some of the disk tests. Unfortunately, an eSATA attached drive in an enclosure will be recognised as a SCSI drive. Such a drive, strictly, has Log pages instead of SMART data. So although the SMART data is available via the enclosure USB Bridge (and pass through), SeaTools says that its SMART test is unavailable. The WMI SMART data fills in this gap and is obtained by querying the same drive in the same enclosure and on the same connection that you ran the Test Tool on. You will need this information to persuade the manufacturer that the drive has failed in order to get a replacement in case the test tool won't do the SMART tests. Please note that all this information helps you build a solid case for a replacement if the drive is under warranty but CANNOT guarantee you will get a replacement.

If your drive is under warranty (and given the caveats above), you should be able to get the drive replaced by the manufacturer, free of charge. Note that Seagate (and other manufacturers) make a lot of fuss about people returning healthy disk drives, so you need to run the tests, and if you get a failure, the Test Tool should give you an error code that can be used to return the drive (but again, note that if the test tool won't do the SMART tests, it might not give an error code which is why you need to get the SMART data by other means, as shown above, and then use your powers of persuasion to get a replacement). Always take screen shots of the test tool once it has completed its tests and save any results to a file (if the test tool lets you do this), and include any WMI SMART data to back up your claim for a replacement.

Of course if your drive is not a Seagate, you can try the relevant manufacturer's Tool to test your drive.