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Mark Forrest wrote: > Does anyone have a checklist of ideal storage conditions for different > digital formats - CDs, different types of floppy disc, external hard drives, > etc. > > I've been debating whether to respond on this, but in the light of your own later followup, as well as other responses, I think I ought to. I think it's worth recognising that there's a world of difference between ideal storage conditions, acceptable storage conditions and risky ones. But one also needs to ask why this material is there and for how long. The TNA guidance that someone pointed to is a reasonable summary of the ideal requirements. It captures all of the essential information in the many parts of BS 4783 (which itself is strongly related to the ISO series that Stephen Gray referred to, so far as I know.) When I've given training courses for archivists and records managers in the past, I've started with that information about ideal conditions. Most of us can't afford to create storage environments with such ideal conditions, though. It then becomes useful to know what the effect is of being removed from the ideal. Luckily there's a fair amount of knowledge about that, for paper as well as digital media. So, to your next point: > Our film and sound archive seems to have been used as the default option, but > I'm not sjure if this is really necessary and wonder if storage in general > strongrooms or unreglated secure rooms is likely to cause long term damage > There are a number of ways in which non-ideal conditions affect digital media. By far the worst are conditions where temperature and/or humidity undergo significant rapid change on a regular basis. Continuous storage at a temperature that is somewhat higher than ideal is probably safer than storage in a room where temperature is usually within ideal limits but undergos fluctuations of over 10 degrees in under an hour on a regular basis, for instance. Very low humidity and/or significantly higher temperatures are also damaging. Humidity high enough to cause condensation also isn't good. But very low temperatures aren't a risk for most media - indeed some studies have shown that storage at typical refrigerator temperatures (about 4C) extends the life of many digital media. Whichever you choose, note also the part of the TNA guidance about acclimatisation. Storage temperatures are not operating temperatures; it's often ideal to allow media to undergo 24 hours of adjustment before trying to use it after long-term storage. (The same is true when bringing it in from an uncontrolled environment.) One other risk that's sometimes forgotten is from pollutants in the atmosphere. Volatile chemicals and hydrocarbons can cause significant damage to tape, CD and disk surfaces. So, don't use freshly-painted rooms and avoid air intakes that are close to streets full of heavy traffic if possible. If you can't avoid this, just accept that the predicted lifetime of your media is being reduced by some percentage. But even assuming you have some ideal storage conditions, you must think why you are planning to store these things for extended periods of time. No one should be planning long-term storage for floppy disks, for instance; they should be planning to copy the contents to something more durable in the short term. What conditions the floppies are stored in the interim probably won't matter that much. You should be checking the contents regularly for readability - ideally every six months (again, the TNA guidance covers this.) I think that you'll discover problems with this in timeframes of a few years with many types of media. CD and DVD, as widespread consumer formats, are likely to be supported by hardware and software longer than floppy disks, for instance. But I would not trust hard disks in storage for longer than 3 years if they are relatively recent. (Oddly enough older drives are likely to last longer; they weren't being manufactured to a price point quite as much as more modern portable drives.) So, don't store your media somewhere where the fluctuations are great, but beyond that don't worry. Worry more that you should be copying regularly to something else - even as simple disk images, without worrying about metadata and file format issues which you mention. Hope this is of some help. -- Kevin Ashley. Director, Digital Curation Centre http://www.dcc.ac.uk/ E: [log in to unmask] @kevingashley http://slideshare.net/kevinashley T: +44 131 651 3823 P: DCC, Appleton Tower, Crichton St, Edinburgh EH8 9LE M: +44 7817 402 498 DCC Helpdesk: +44 131 651 1239 Contact the list owner for assistance at [log in to unmask] For information about joining, leaving and suspending mail (eg during a holiday) see the list website at https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=archives-nra