Options for reading faulty hard disks - Page 1
Forum section: electronics / general

author: dexters_lab
author_rank: Unknown
timestamp: October 27, 2017, 12:55:35 pm
content: I have an old Seagate ST2502N (aka CDC) 5.25" half-height SCSI disk that i have not been able to read and want to run through any options i have to be able to recover the data off it.As it is now, it spins up, initialises, sounds normal, responds to SCSI commands and i am able to read sector 0, but any other sector throws up a CRC error.i wonder if there is a possibility of getting it to output data even though there is a CRC error, or maybe trying to find replacement controller board for it?any other thoughts?

author: alanb
author_rank: Frequent Contributor
timestamp: October 27, 2017, 03:13:32 pm
content: If it has a commercial value its worth contacting Kroll,https://www.krollontrack.co.uk/services/data-recovery/I used them a few years ago on a very difficult data recover job. They are expensive but their results are impressive.they also had a range of free and low cost data recovery tools for DIY jobs, I haven't checked recently to see what is currently available.

author: borjam
author_rank: Unknown
timestamp: October 27, 2017, 03:15:23 pm
content: There is a program called ddrescue that will try to read every block. If the disk only has certain areas damaged it may be able to recover the restof the information.https://www.gnu.org/software/ddrescue/I've used it successfully several times in the past.

author: dexters_lab
author_rank: Unknown
timestamp: October 27, 2017, 04:27:10 pm
content: Quote from: alanb on October 27, 2017, 03:13:32 pmit's nothing of value, it's just my stupid curiosity that makes me want to take a lookthanks for mentioning Kroll, they do seem to be well respected, i spoke with them recently about something unrelated to this

author: abraxa
author_rank: Frequent Contributor
timestamp: October 27, 2017, 08:50:16 pm
content: Did you rule out the cable and controller? Just wondering if the hard drive might not be to blame here.

author: cdev
author_rank: Super Contributor
timestamp: October 27, 2017, 09:03:48 pm
content: Newer Seagate drives have a UART interface which might be helpful?If you can get it to output a bit more... I don't know that much about SCSI.. I do remember termination was all important.. They are very very finicky.I second the ddrescue recommendation, I also have had success putting nonworking hard drives in a plastic bag (to keep moisture from condensation out- using a USB extension cable and a USB to IDE or USB to SATA converter and put them in a freezer. The freezer extends the period of time that they work. Alternatively keep it outside but train a very high intensity fan right on it. The cooling is important. I dont know if that would work with SCSI.. Is there any such thing as a USB SCSI adapter?Quote from: dexters_lab on October 27, 2017, 12:55:35 pm

author: johnkenyon
author_rank: Regular Contributor
timestamp: October 28, 2017, 12:29:40 am
content: Have you tried disabling or enabling parity checking on the drive?http://stason.org/TULARC/pc/hard-drives-hdd/seagate/ST2502N-WREN-435MB-5-25-HH-SCSI1-SE.htmlrefers to(3) CLOSED Parity checking by the WREN 6HH is enabled./John

author: dexters_lab
author_rank: Unknown
timestamp: October 29, 2017, 09:05:56 am
content: Quote from: abraxa on October 27, 2017, 08:50:16 pmIt is the drive, it does exactly the same on different systems with different cables etc.Quote from: johnkenyon on October 28, 2017, 12:29:40 amParity is a scsi protocol thing rather than a drive media setting, i will give it a try though

author: janoc
author_rank: Super Contributor
timestamp: October 29, 2017, 12:33:55 pm
content: If the drive is throwing CRC errors oneverysector except 0, that is very unlikely a media problem (bad blocks). So the ddrescue and similar tools won't help - you will get garbage.That sounds more like a misaligned/damaged head to me and probably not fixable without a clean room and special equipment.

author: Halcyon
author_rank: Unknown
timestamp: October 30, 2017, 11:15:54 pm
content: I use a number of different methods but they all involve some fairly expensive gear.Usually if you have a faulty head, you can disable that one but read back all the data from the good heads and create an image (albeit missing the data from the faulty head). From there, you can do a second pass using just the faulty head (reading back very slowly and disabling the drives ECC features) to "fill in" as much of the missing data as possible. Failing that, it usually involves a platter/head assembly swap.I also find reading data backwards on failing drives can be particularly effective.Again, these methods involve specialist hardware, but I thought I'd share some of the methods I've personally used.EDIT: I've also sent you a PM.

author: wraper
author_rank: Unknown
timestamp: October 30, 2017, 11:22:39 pm
content: Quote from: janoc on October 29, 2017, 12:33:55 pmFor this old drive clean room is not such a big issue. As it has very low data density, room with the least amount of dust like bathroom may work quiet fine.

author: Halcyon
author_rank: Unknown
timestamp: October 31, 2017, 02:19:14 am
content: Quote from: wraper on October 30, 2017, 11:22:39 pmI use a laminar flow cabinet within an ordinary office/lab and it does the job just fine, even on modern "high density" hard disks. The whole clean room thing is a bit of a wank. Sure if you're manufacturing or refurbishing hard disks, absolutely, a clean room is required, but not if you're just doing repairs in order to copy data to another target. The cabinet along with nitrile gloves and maybe a P2 face mask is usually enough to prevent contamination.That being said, those drives probably won't be viable for long given that they usually come past my desk with problems in the first place.

author: erikg
author_rank: Contributor
timestamp: November 02, 2017, 02:02:37 pm
content: Just a quick suggestion... in case the problem is caused or made worse by faulty drive electronics, it's fairly simple to acquire the same drive model from EBay and swap the circuit board.If it's a physical problem with the drive itself this won't help, but if it's actually a problem with the drive electronics this might let you read it.

author: CJay
author_rank: Super Contributor
timestamp: November 02, 2017, 04:31:06 pm
content: Quote from: erikg on November 02, 2017, 02:02:37 pmThis does work nicely with drives of that era, they're voicecoil drives so head alignment isn't an issue, they use an embedded servo track which allows them to self align, if they can't read it it's because there's a fault.I'd be paying attention to the contents of sector 0 to see if I could discern what format the drive thinks it is (I realise that it's the drive that's returning CRC errors whichis 'below' the format)It's also possible that the drive is using some very weird sector sizing, those drives were used in ICL mini and mainframe computers and they had some bizarre firmware on them, I had several dozen of them at one point and couldn't make them behave at all.

author: erikg
author_rank: Contributor
timestamp: November 02, 2017, 06:42:22 pm
content: QuoteThat's true, but of course it could also be that the circuitry that calculates the CRC value has blown a bit - that would create the same error message.

author: dexters_lab
author_rank: Unknown
timestamp: November 03, 2017, 10:29:57 am
content: there are drives of the same model on ebay and i did consider buying one and swapping the controller board but the ones available are all £100+ to buy. The data is not worth that much to meCjay: the drive is from one of my quantel paintboxes, it will be standard 512byte sectors etci have found i can read some sectors though after some playing with it... it seems to have areas of several 100 readable sectors then an area of 100s of sectors of unreadable etc etc i can't see any pattern to it though

author: CJay
author_rank: Super Contributor
timestamp: November 03, 2017, 01:28:21 pm
content: Quote from: dexters_lab on November 03, 2017, 10:29:57 amThen I think you've got a duff head or head amp in there, it's possible to repair the head amps but I believe replacing the head itself is nigh on impossible without a servo writer rig, they have a tendency to cost a *lot* of money and would destroy the data anyway.It might be worth poking and prodding about for dry joints on the board and of course reseating cables and connections between board and disk pack

author: Khendrask
author_rank: Contributor
timestamp: December 07, 2017, 03:58:40 pm
content: Off topic, but it is sad that none of the install programs I have for my job would even fit on that drive.For that matter, neither would the installer for the OS's I use.