I have seen this before with both disk and tape media, where a backup
job with no errors cannot later be restored due to i/o errors. The
simple answer is that media can fail, even when offline, which is one of
the reasons we make more than one backup.
It is possible, if cumbersome and expensive, to write to RAID-1 storage,
which would practically eliminate this issue. If restore from a
secondary backup is not acceptable for whatever reason, then more fault
tolerant hardware is the only answer.
The alternative I would recommend, where restore from secondary backup
is acceptable, is to set a volume size limit for disk volumes. Disk
media usually fails in a small area of the media, meaning that if there
are multiple volumes on the disk then only one (or a few) are likely to
be affected. Huge volumes are at greater risk. Smaller volume size does
not eliminate the problem, but mitigates the risk at the expense of a
somewhat larger database size.
On 6/28/2014 3:30 AM, Kern Sibbald wrote:
> It is unlikely that this is a Bacula problem, especially considering
> your remark that you have
> used it for years and never had any problems.
>
> My best guess is that you have bad media or a bad medium or a bad
> connector. When writing, unless the OS reports an error, Bacula assumes
> the write is good. That is, it does not re-read the data. If you want
> to verify then you must run a Bacula verify job after the backup job.
>
> I suspect that there is no difference between Bacula and rsync except
> that rsync is writing on a part of the media that is good and Bacula is
> writing elsewhere.
>
> There are several solutions (this is not exhaustive): 1. Get new
> media. 2. Use a more reliable form of backup device (USB is relatively
> unreliable compared to SATA, ...). 3. Run read/write disk tests on your
> USB disk (note: this will destroy any existing data). 4. Check your OS
> logs. They may show low level errors that are not reported to Bacula.
> If you have such errors, you must eliminate them to have reliable
> backups (or said the other way around: reliable backups *never* generate
> any OS device errors).
>
> Best regards,
> Kern
>
> On 06/27/2014 04:36 PM, advantex AT posteo DOT de wrote:
>> Hi Liste,
>>
>> I am using Bacula for years now and had no trouble so far.
>> But now it really hits me.
>> Well it worked smoothly .. until restore. (on ubuntu 12LTS and ubuntu
>> 14, bacula version 5.2.6)
>> The files were on USB disk. To be on the safe side I recreated
>> everything on local sata again. Same result.
>> I do tons of rsync on that disc with no problem, checked with smart,
>> upgraded the system and no change. If I run bacula-sd with -p the
>> restore is pulled through but the files are really corrupted.
>>
>> Luckily I have another backup. But this is really a bad move.
>> How can I rely on the backup of bacula now? (i.e. Rsync tells me at
>> once if the file is corrupt) Do I really have to do a checking restore
>> on every job now?
>>
>> Could you give me a hint what might be the problem?
>> Thanks
>> G.
>>
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