HP Smart Array E200i SaS Drive

We have just competed a successful recovery from an HP Smart Array E200i RAID array. Not a standard case this. It had x3 DG146BB976 2.5″ SaS drives, two of which had been overwritten with a new RAID 1 mirror.

We found the disk order which was not the same as the labelled numbers. This is often the case. Also, due to the rebuild that had occurred we had to drop one of the disks and virtually rebuild it using the parity information from the other disks.

3 DG146BB976 / ST9146802SS SaS Drives

 Today’s large SATA drives shouldn’t be used in 4 drive RAID 5 arrays due to the high likelihood of a read error after a drive failure, which will abort the RAID rebuild.

It is a common misconception that if you run a RAID system then you can avoid keeping backups. Although fault tolerant to a point, there are plenty of issues with RAIDs that can at best cause lengthy downtime and at worst prevent any recovery at all.

More info on RAID Recovery

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Due to the complex nature of these NAS devices, we always recommend they are backed up to another form of media. Although recovery is possible, it can be expensive and relatively time consuming. Also if the unit is powered on and rebuilds are attempted then the recovery can be made more complicated or even impossible.

A Little Background

The LaCie 5Big NAS device contains five hard drives and allows for a number of different configurations. One of these configurations is RAID 6, which works in much the same way as RAID 5, but with an additional parity stripe. This additional parity stripe uses an algorithm which requires a relatively high processing overhead, so RAID 6 has rarely been seen in consumer level devices. The low cost of processing means that RAID 6 is now a viable option for embedded NAS devices such as the LaCie 5Big.

The advantage of RAID 6 over RAID 5 is that with 5 disks it can theoretically cope with two disk failures. This gets round an increasingly common problem with large capacity RAID 5 arrays where if a second disk fails whilst rebuilding a failed disk, there should be enough parity information to continue the rebuild successfully.

If you have a failed or broken LaCie 5Big then use the contact details on the right to contact us. Alternatively you can leave a comment here and we will get back to you.

The worrying thing for users is that even drives used in RAID 1 mirror mode are having problems, where either both drives are failing at the same time or where one drive has failed in the past and the other following suit some time later.

It is an important reminder that RAID does not equal backup. If there is important data on these types of devices, it also needs to be copied to another device for peace of mind.

We are currently able to recover the data from these devices using a combination of firmware repairs and other recovery methods.

An interesting note is that we have also seen a small increase in other WD drives at the moment, such as the 320GB WD3200AAJS drives from iMacs and WD5000AACS drives from external enclosures.

More to come I’m sure…

FreenNAS - Network Attached Storage

We have recently been trying out FreeNAS as a way to add some storage to our internal network. First impressions are positive. We are able to utilise an old spare low power PC to run the software from a compact flash card. We currently use four 1TB drives in two separate hardware RAID 0 arrays. This gives us two 2TB volumes which we can access over the network on either Windows (SMB/CIFS) or Mac (AFP).

Setup was simple, by booting a liveCD and choosing the 64MB compact flash card to install to. Once setup, the server can be run headless (without a monitor) and configured via the handy web interface. It is possible to setup hard disks, file sharing protocols, and even a transmission torrent server and iTunes music server, all directly from the web interface. The web interface also shows the status of CPU and memory usage and can also provide graphs for disk access and network throughput.

It takes some minor setup to access the drives in Windows by mapping the network drives, however no setup is required on the Mac end. The server shows up in the finder sidebar and is just a click away from the network volumes. An overview from the FreeNAS website is included below:

FreeNAS is a free NAS (Network-Attached Storage) server, supporting: CIFS (samba), FTP, NFS, AFP, RSYNC, iSCSI protocols, S.M.A.R.T., local user authentication, Software RAID (0,1,5) with a Full WEB configuration interface.
FreeNAS takes less than 32MB for version’s up to 0.686.x and 32+ MB from version 0.69
Can be installed  on Compact Flash, USB key, USB key or just run as LiveCD saving the configuration file on floppy or USB key .
The minimal FreeBSD distribution, Web interface, PHP scripts and documentation are based on M0n0wall.

I would be interested to run FreeNAS on a small form factor Atom based PC, maybe using external storage drives. The EEE Box would make an interesting FreeNAS server.

LaCie Big Disk

Over the years we have seen stacks of LaCie Big Disks (and quite a few LaCie Bigger Disks too). With their designer looks and an abundance of different interfaces, it is no surprise that they are so popular. There is however one main reason that people send us their drives, and that is because they are not working.

Size Matters

Those of you familiar with hard drives will be aware that these LaCie drives are substantially larger in physical size and storage capacity when compared to a standalone hard disk drive. The reason being is that the LaCie Big Disk contains two hard disks (and the LaCie Bigger Disk contains four hard drives). Of course when you attach the drive to your computer you only see one volume. This is due to a RAID controller inside the LaCie drive which allows for multiple disks to appear as one large, usable disk. The main advantage to this setup is that read and write speeds can be very fast, as the reads and writes are spread over multiple disks. Another bonus is that the capacity of the volume is as large as the two drives. So two 500GB drives will give you a 1TB volume. There is however a massive downside to all of this clever RAID business which boils down to some simple mathematics.

Failures

The larger the number of hard disk drives used in this particular striped (RAID 0) setup, the more chance that one of them will fail, therefore a higher chance that you will lose all of the data stored on these drives. The way a RAID 0 stripe works is to distribute the data across the disks at block level. The amount of blocks used for each stripe is determined by the RAID controller and varies between different manufacturers. What this means, from a data recovery point of view is that in order to extract data from a LaCie Big Disk, you need to figure out the block size, and read the data from both drives in sequence, in order to extract usable data. This sounds a lot more complicated than it actually is and is often explained with the analogy of a filing cabinet.

Imagine the LaCie Big Disk is a filing cabinet. The cabinet has two drawers (disks) with an index in the first drawer. Now imagine that when you save a file into the cabinet, all of the odd numbered pages are put into the first drawer, and all of the even numbered pages are put into the second drawer. Once saved, the files location is stored in the index. In order to read back the saved file, it must first be collected from the relevant drawers, one page from each drawer at a time, and arranged into the correct order.

This is all great until a problem occurs. What happens when one of the drawers becomes damaged and can no longer be opened. Sure you can access all of the pages in the other drawer but having every other page is not much use to anybody! So until you can access both drawers, the documents are worthless.

Special Hard Drives?

The hard drives in a LaCie Big Disk are much the same as any other hard drive on the market. This means they are just as likely to have the same failures as a standalone drive. They suffer from electronic problems on the PCB, firmware corruption and also internal component failure and head crashes. These are problems which need to be overcome before any attempt at a recovery is even possible.

Aside from the usual hard drive problems, we have also seen other problems such as failed power supplies or damaged circuit boards within the LaCie Big Disk, which prevent access to the stored data.

This is why we have spent a lot of time researching the process of recovering data from RAID systems such as the LaCie Big Disk. We follow the same precautions with RAID as we do with single volume drives.

• We make binary images of all of the individual hard drives on a read-only basis to protect against drive failure.
• We don’t use the original hardware to read the RAID data, as this may be part of the problem.
• We never write the recovered data back to the LaCie Big Disk, as this would prevent any further recovery process if it was required.

As with all data recovery, the most important thing to remember is that any attempts to access the data without following strict precautions could result in the data being either lost forever, or extremely expensive to get back.

The best advice is to keep these drives backed up as regularly as possible to avoid future headaches.

Checking file system on C:

The type of file system is NTFS

One of your disks needs to be checked for consistency. You may cancel the disk check, but it is strongly recommended that you continue.

To skip disk checking, press any key within  7  second(s).