On Aug 12 2015, Keebs <[email protected]> wrote:
> On Tuesday, August 11, 2015 at 1:42:15 PM UTC-4, Nikolaus Rath wrote:
>> On Aug 11 2015, Keebs <[email protected] <javascript:>> wrote:
>>> I have a backup saving to a samba share backed by S3QL. The file
>>> "saves" successfully to the share and S3QL starts the upload to S3
>>> as normal. After the save to the share completes a verify is run on
>>> the file, but this is where it fails.
>>
>> What exactly fails?
>
> I wish I could answer this in more detail. Backup Exec reports Error
> V-79-57344-33992 which correlates to:
> *Storage device has reported an error on a request to read data from media.
> Error reported: The request could not be performed because of an I/O device
> error.*
>
> The subcode for the failure is:
> *Error: e00084c8 - The backup storage device has failed*
In other words, you're having a problem with "Backup Exec" rather than
S3QL.
>> > I understand the eventual consistency issues, so I enlarged
>> > the s3ql cache to exceed the size of the file being saved thinking
>> > that
>> [...]
>>
>> No, quite obviously you don't understand the eventual consistency issues
>> :-). As long as the file system is mounted, they can not cause you any
>> problems.
>>
>>
> The way I understand it:
>
> Let's say I have an S3QL cache size of 2GB.
> Now I write a 4GB file. The first 2GB will copy quickly and fill the cache
> while the latter 2GB of the file will slowly save as cache is freed.
> Once the file has finished copying locally, the S3QL cache will still be
> full with the final 2GB of the file as it continues to upload to S3.
>
> Immediately after the backup thinks the file has been saved, it wants to
> verify the file so it is now requesting the file to be read back from the
> beginning, but the beginning of the file is no longer in the S3QL cache
> because the final 2gb of the file has the S3QL cache consumed until it
> frees some space to re-download the beginning of the file from S3 - which
> is where the eventual consistency could theoretically come into play. Until
> the time cache has been freed, the beginning of the file will not be
> available to be read.
>
> What am I misunderstanding?
The last part. S3QL knows that it has uploaded the data, so eventual
consistency will not come into play. If the data is not yet available
for download, S3QL will wait until it becomes available without the
client application ever noticing anything.
Best,
-Nikolaus
--
GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F
Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F
»Time flies like an arrow, fruit flies like a Banana.«
--
You received this message because you are subscribed to the Google Groups
"s3ql" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
