Which is exactly what they are claiming. They "recycled" them, but only the ones that covered 2009-2011...you know, the ones that mattered.
Ed as I understand it this is the policy that the IRS had in place that they are claiming. Each employee has a quota in place of something like 150MB which is actually quite a bit for email if there isn't any attachments. Those are stored on the server, this server is going to have disks in RAID array which means it has multiple disks. If one disk fails you pop it out and put another in it's place and it can be rebuilt with data from the other disks. It has redundancy built in case of disk failures. The primary disks are in effect your primary backup because disk failure is the number one reason you would lose data. Had there been no disk quota we wouldn't be having this discussion.
The tapes they are talking about used to backup this server that are being recycled are really secondary backups but play a vital role in data integrity. These are probably full backups and they might make one every day or perhaps incremental backups in real time. Supposing they make full backups daily, if they are recycling them every 180 days they have 180 copies of the same data with each subsequent backup having the most recent emails. This may sound excessive at first but it is important because if the data on the server becomes corrupted you have snapshots in time of the state of the data for up to six months into the past. If you only have one backup and recycle it daily and the data on the server gets corrupted your single backup is corrupted as well if you don't catch it. Recycling some these would make sense however recycling all of them does not.
For example I make a daily backup of this forum, I have snapshot of the state of the database for each of the last 7 days and it rolls over deleting the oldest(this would be like recycling the tape). Every Saturday that backup goes into my weekly backup so I also have snapshot of the data for each of the last 4 weeks deleting the oldest one. Every first of the month it goes into my monthly backup so I have backup for each of the last 12 months deleting the oldest one. I also have a yearly backup that never gets deleted. This way you have snapshots but you don't have an excessive amount of redundant data. This is not perfect and I have plans to improve it with an additional incremental backup that will be taken every hour. Had the IRS used a similar policy we would not be having this discussion.
Getting back to the quota this is where the breakdown is, the IRS is saying it was their policy that once the user hit their quota limit they were supposed to move those emails onto their desktop PC's which is one of the most ridiculous things I have ever heard because now all these safeguards against data loss are no longer in play. Besides that since it's the law these emails be retained it has to be management nightmare, if this is in fact the IRS's policy it's a clear example of how inefficient our government could be. Lois Lerner or any other IRS employees shouldn't be spending their time managing their email account. One other thing on this disk quota, as I understand it with the software they were using by default this is a soft limit. When the user deletes an email it's not actually deleted but gets marked for deletion similar to having a recycle bin. Only a server admin would actually be able to delete the message or change how this default works.
As far as this drive goes they are claiming bad sectors which happens but the scenario they have outlined is impossible. Had they said some of the data was lost that is plausible but not all of it. The only way you lose that amount of data off a drive is catastrophic physical damage or someone purposely corrupted it before the technicians got to it. As far as it being recycled that is going to be normal protocol for a bad drive once it's no longer of use, I don't know what their policy is but usually they first going to wipe the drive either using software or a magnetic degausser which itself is going to render any data on the drive irretrievable. Then they are shredded just for the hell of it....