IFR/Aeroflex 2975 HDD to CF conversion

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IFR/Aeroflex 2975 HDD to CF conversion

Post by duggerd »


The 2975 uses a 2.5" IDE hard drive that may fail over time. The software options and serial number are also stored on the hard drive. The hard drive can be backed up to a file, and restored to an identical model hard drive. However, there are only used/new old stock drives available and at some point all of those will eventually fail. Using a CF card with compatible geometry, the hard drive can be replaced. The following instructions also apply to backing up/restoring to a hard drive rather than a CF card.

I would like to thank Wowbagger on this forum for his posts over the years, with some very helpful technical insight into the 2975 architecture.


Only attempt this conversion if you feel you understand the following steps (read them first!) and have a basic understanding of Linux. There are no second chances when dealing with low level tools such as dd and raw access to hard drives. If you modify something, that's it, game over, that data is changed with no chance of recovery. Don't blame me when something goes wrong because you didn't know what you were doing.

Be careful when removing the processor backplane card PCB, as on my 2975 (S/N: 5980034XX) along with the backplane connectors on the bottom of the card, there are two connectors (0.1" and FFC) near the front panel. If you just pull the card out, you risk damaging these interconnects.

Also take pictures of all the BIOS settings of your unit (F2 on boot) before you open it up, as not only is that a good backup to have for when the CMOS battery dies, but if you happen to knock the CR2032 battery out or short out the battery positive line to ground you will have a backup.


1. USB to IDE adapter THAT YOU TRUST

I've owned several cheap USB (2.0 and 3.0) to IDE/SATA adapters over the years and have never been happy with the quality of any of them. If you work with computers for a living, consider getting a forensic adapter, which is of considerably better quality in addition to including a hardware write blocker (will prevent all writes to the connected disk - some can be disabled for when you need to write to the disk). I've been happy with my Tableau T35u (~$400 USD in 2019 including an assortment of adapters).

2. Swissbit 32GB C-56 CF card, Swissbit P/N: SFCF032GH1AF2TO-I-LT-51P-STD, Digi-Key P/N: 1052-1379-ND, Mouser P/N: 922-606718, ~$100 USD in 2019

This CF card has essentially the same geometry as the 30GB Hitachi Endurastar HEJ423030F9AT00 drive (Cylinders: 16383, Heads: 16, Sectors: 63). Due to the way LBA works, this will also mean it will have the same numbering for the first 30GB. It uses MLC flash, which usually isn't a good idea to install an OS on or to be used for cyclical logging due to the number of writes that happen in those use cases. However, the 2975 runs VxWorks which is designed for systems running on embedded hardware that might have these limitations. The Aeroflex applications running also do not write to the disk that much (maybe with the exception of the P25 logger). The Swissbit sales material say that the MLC is running in 'pSLC' mode, which I assume means it uses a FTL that has good wear leveling support.

IMPORTANT: If your drive is greater than 32GB in size, it may not be safe to write the entire image over and truncate the data that is over 32GB. I have not investigated the filesystems/partition architecture used to say for sure. I have read here that a 40GB drive was also used, so it would be safer to write that disk to a 64GB CF card (next larger size - Swissbit 64GB C-56 CF card, Swissbit P/N: SFCF064GH1AF4TO-I-LT-51P-STD, Digi-Key P/N: 1052-1380-ND, Mouser P/N: 922-606720, ~$200 USD in 2019). I have not tested this specific configuration, so I can't make any guarantees though. However, in all cases the drive CHS geometry MUST match the CF card. The 16GB/32GB/64GB variants of the Swissbit C-56 CF card all have the same CHS geometry (Cylinders: 16383, Heads: 16, Sectors: 63). If someone has a disk that is not 30/40GB 16383/16/63, let me know and I'll try to help out.

3. 44 pin 2.5" IDE (PATA) to CF adapter, Syba SD-ADA45006, ~$10 USD in 2019

These have been available for some time, and are overall of a decent quality. They are in the form factor of a 2.5" drive, so they have the mounting holes required to attach to the processor backplane card PCB. The conversion between IDE and CF is only physical, so really any IDE to CF adapter should work. One modification needed is to remove pin 20, which is the key and blocked in most mating connectors. It is on the top row of pins (when the slave CF slot is facing up and away from you), and the pin is the 10th from the left (after removing the pin there should be 9 pins on the left and 12 pins on the right). There is also no positive retention function on the CF card sockets used, so a piece of Kapton tape over the CF card and case should be used to prevent the CF card from falling out from vibration/handling over time. Only use the master CF slot - leave the slave slot empty.

4. Physical computer running Linux

I would NOT recommend using a virtual machine running on another OS, as when you first connect the USB to IDE adapter, the drive would first be connected to the host machine. Without a write blocker, it might get "automatically repaired" (written to and screwed up) by the host OS. The utilities dd, gzip, and sha256sum should also be available at a minimum.


1. disable automount of connected drive partitions

2. connect backup destination disk and mount

3. connect source disk but do NOT mount

4. read the source disk contents and stream them into a compressed file (gzip n flag as so not to record current timestamp in order to make output deterministic)
dd if=/dev/sdX status=progress | gzip -n > 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz

5. get the sha256 of the compressed disk image
sha256sum 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz > 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz.sha256

6. get the sha256 of the actual disk image (trusting that gzip does its job right)
gzip -d -c 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz | sha256sum > 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.sha256

7. disconnect source disk

8. dismount and disconnect backup destination disk


1. disable automount of connected drive partitions

2. connect backup source disk and mount

3. connect destination disk but do NOT mount

4. verify the checksum of the compressed disk image
cat 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz | sha256sum -c 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz.sha256

5. verify the checksum of the raw disk image
gzip -d -c 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz | sha256sum -c 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.sha256

6. decompress the compressed disk image and write it to the destination disk
gzip -d -c 2975_XXXXXXXXX_hdd_backup_YYYY-MM-DD_N.img.gz | dd of=/dev/sdX status=progress

7. disconnect destination disk

8. dismount and disconnect backup destination disk
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Re: IFR/Aeroflex 2975 HDD to CF conversion

Post by bigbop »

A frigg'in EXCELLENT writeup!!!

I did this 2 months ago to get a 2nd 2975 up and running again.
There is an eBay vendor selling the Endurastar drives but although the photo shows a date on the drive of 2016, the drives you get are from 2006.
They're around $13US ea so I bought 2 and cloned both so I have a spare.

For Linux, I just used a LiveCD of R.I.P. (Recovery is possible), opened a terminal window and used ddrescue instead of dd - in case the source drive had any issues (2975's are OLD).
Crazy thing is the source 2975 hangs on a front panel power-down but the target unit shuts down just fine.

I highly recommend duggerd's instructions.

Final thought: DO NOT try to look at the cloned drive on a Windows system - it WILL be corrupted.

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