RAID 5 data recovery from a Dell Poweredge 2900 Server

 

 

We were recently called to help a Dublin accountancy firm recover data from a failed 3 disk RAID 5 array.

 

Our diagnostics revealed that 2 out of their 3 SAS drives had failed. One drive had suffered component failure on it’s electronic assembly; the other had head disk assembly problems that needed work in our clean-room.

 

First of all, we fixed the electronic issues with the defective PCB. Then we performed a head disk assembly swap. (The donor parts we already had in stock).

 

Once the defective drives were fixed – it was now time to image them. Imaging drives before a RAID reconstruct is an important step to maximise the integrity of the data.

 

When the drive imaging process had completed we proceeded to reconstruct the RAID 5 array. This is time a consuming and intricate but rewarding process knowing that you are probably saving the client 100’s of hours of labour redoing work that has already been completed.

 

With the RAID rebuild finally complete – we transferred all their data onto a portable high capacity USB external drive. We then invited them to perform a check on their files using a remote file viewer. Everything was to their complete satisfaction.

 

Without a successful data recovery – they would have had to reconstruct month’s worth of accounting data. This would have been a serious drain on their productivity not to mention the harm it would have caused their reputation.

 

Lesson learnt? A lot of users still think that just because their data is on a “server” it is automatically safe. It’s not. Servers fail too. The accountancy firm is now backing up their data onto their new server and are using a reputable online backup service.

Seagate beats Western Digital Data in the Data Density Race

Seagate has beaten Western Digital to the post in breaking the one terabit per square inch data barrier on a disk platter. (Now we know why they were so anxious to acquire Maxtor and their R&D facility!)

Currently, with a data density of 620 gigabits per square inch, the maximum capacity of a 3.5 inch is 3TB. With this announcement from Seagate, we are likely to see hard drive capacities shoot up to 6TBs for 3.5” drives and 2TB for 2.5” models. All of this is possible by using lasers to heat tiny areas of the platter (a.k.a Heat Assisted Magnetic Recording, as discussed on this blog two weeks ago).

This sounds all very well in theory but from a data recovery point of view a defective drive head could now cause even more damage. Currently, a defective drive head can cause bit corruption. At worst, a physically damaged drive head can have a scouring effect as it moves across the platters. But having a defective drive head which also has a microscopic laser attached to it could compound or magnify even small drive head defects. Seagate have not mentioned anything in their press releases about how the laser will impact power consumption and more importantly has not mentioned anything about how the laser will impact read /write performance. We look forward to purchasing one of these drives to put it through it’s paces in our lab.

3rd Platters and the 228 Year Old Hard Drive

 

For most 2.5” inch drives (or simply laptop hard drives), 1 or 2 platters (platters are the actual disks where the data is stored) have been the de facto standard for a number of years now.

But, around this time last year, Seagate brought out their Savvio drive with 3 platters in it.  Now Western Digital have thrown their hat into the ring and brought out their own three platter 2.5” drive called the S25. This disk, like the Savvio, has a capacity of 900GB. On their website, Western digital claim the drive has a whopping 2 million hour MTBF (mean time before failure). Now, over the years I have heard some ludicrous claims proffered by drive manufacturers but claiming this MTBF figure (i.e. half the drives will fail within 228 years of operation) is farcical.

One of the largest hard drive studies ever untaken in the world “Failure Trends in Large Disk Drive Population” was conducted by the engineers at Google. It helps shed some light on some of the manufacturer’s claims. They noted “situations where a drive tester consistently ‘green lights’ a unit that invariably fails in the field” In other words, in manufacturer’s tests, they pass drives that would fail in real life.

Storage could be considered a critical area of the I.T. industry. Everyday we rely on hard drives from surfing a webpage, to storing a thesis and to companies storing whole databases on them.  Computer users (consumer and enterprise) want storage options that have reasonable performance coupled with a reasonable level of giga/tera-bytes at a reasonable price. They do not want spurious numbers or claims pulled out of the air so some marketing department can get their egos stroked. With realistic expectations of hard drive failure rates, users can formulate better disaster recovery plans. Forewarned is forearmed.

Trinity College Dublin and Western Digital working together to maximise the Storage Space of Hard Drives with Laser Assisted Recording.

The Trinity College based Centre for Research on Adaptive Nanostructures and Nanodevices is currently working with Western Digital on maximising the storage space of the traditional hard drive.

The areal density or amount of data that can be stored on a square inch of disk (platter) has been increasing every year. For example, 10 years ago, if you bought a standard desktop PC it would probably have come with an 80GB drive. Now, a standard PC will have anything from a 500GB or 1TB hard drive installed as standard.

The last great breakthrough in achieving even greater hard drive densities has been the use of tunnelling magneto-resistive heads with additional heater coils to improve storage efficiency and the recording of data to the platters.

The team at Trinity are now taking this technology one step forward. They are deploying a laser to heat a tiny area of the drive (1000 times smaller than the width of a human hair). By using a laser to increase the temperature of the magnetic material – data can be stored at higher densities with improved read/write functions.

It is great to see such revolutionary heat assisted recording technology which has the potential to change hard drive design being developed on our own doorstep.

All you need to know about NAS Servers

All you need to know about NAS Servers

a G-Tech (Hitachi) NAS Device


Why are NAS devices are replacing servers?

Many NAS servers have the same storage capacity as traditional server but without the administration overhead.

NAS are proving more popular than ever because of the flexibility they offer. If you have employees you are using iPads or Macbooks they can be much more easily facilitated by a NAS than a conventional server. Moreover, you do not need to buy Windows Server 2008 or client access licenses to use a NAS.

What NAS server to get?

The type of NAS you acquire will be determined by a number of factors.

  • How many users are in your office?
  • What sort of data will be stored – documents, application data, video etc?
  • What is the speed of data transfer needed?
  • What sort of network do you have in your office – wired or wireless?
  • Privacy – do you need certain files to have restricted access?
  • Will you need to access your data on the NAS remotely?

Synology Disk Manager User Interface


More specifically, you have to consider the following questions:

– Does the NAS come with standard or proprietary RAID? If your RAID does fail, proprietary RAID might be more expensive and time consuming to restore.

  • What is the user interface like? Is the user interface intuitive or  confusing to use?
  • Does your NAS integrate well with Active Directory?
  • Does the NAS have E-SATA support for fast local backups?

Other Things to Bear in Mind

Check your manufacturer approved list. Not all hard drives are accepted by NAS devices.

What software do I use to manage the NAS?

There are many different software options to manage your NAS settings and shared files. These include FreeNAS, Openfiler, Windows Storage Server or you can use the software that comes with the NAS itself.

Biggest misconception about NAS devices…?

A substantial number of people think that NAS devices are a turnkey solution for complete backup. They are not! A back-up is only valid if it is in two different locations. In addition to a NAS, it is strongly recommended that you backup your data online (the Cloud) or backup via external hard drive or DVDs. (Many NAS devices have USB ports for this very purpose)

What most I.T. vendors won’t tell you.

Many I.T. administrators of smaller businesses will actually deploy an old desktop PC or server with high capacity drives as a NAS device. This can be an inexpensive option for a simple NAS where speedy data throughput is not required.

Advantages of a NAS

– Lower power consumption than a conventional server. Some NAS servers use as little as 8 watts of power.
– Less administration needed. No active directory or domains to manage.
– Most NAS devices will support multiple operating systems. If you have a staff member with a MAC or Linux system – they will still be able to access shared files.
– A NAS is much smaller than an average-sized server. This means it can be easily tucked under a desk or put in cupboard.

Disadvantages of a NAS

– Does not give you the same level of administrative privileges as a server OS such as Windows Small Business Server. For example, for most NAS devices you can only set permissions per share and not per folder. This can make administration be more time consuming if there are some folders you want to keep private such Accounting and Management folders.
– If you’re company is using MS Exchange as an email application, it cannot be run on a NAS.


And Lastly…

Do not connect your NAS directly to mains power. Like with a conventional server, one power surge could damage your drives. To mitigate the risk of this happening, acquire a Uninteruptible Power Supply. A UPS acts as an intermediary between your mains power supply and your NAS. In the event of a power surge happening, the UPS should prevent the surge reaching your NAS and mitigating the need for data recovery.

Advanced Data Recovery Service

We Recovery Data from:

  • IDE / S-ATA and SCSI drives
  • RAID 0.1,2,3,4,5,6
  • Whole disk Encrypted Drives
  • USB Flash Drives
  • 1.8″ inch Netbook drives
  • External Drives
  • Fire, Water and Smoke Damaged Drives
  • Recovery from Windows, MAC and Unix drives

For more information or advice call us on 1890 571 571 (Dublin).