Ask HN: Is it necessary to backup S3? • Hacker News Board

Re: Ask HN: Is it necessary to backup S3?

#11

Post by chaosmachine » Mon, Sep 14, 2009, 2:51 PM UTC

It's necessary, because you never know when you'll accidentally corrupt all your data. Even if Amazon never fails, your application still can.

Re: Ask HN: Is it necessary to backup S3?

#12

Post by byoung2 » Mon, Sep 14, 2009, 2:55 PM UTC

At $0.15/GB it's a no-brainer for the piece of mind. I once heard of a case (not with Amazon) where data was replicated in 3 locations, and data got corrupted in one location and was copied to the others, resulting in corrupted data in all 3.

Re: Ask HN: Is it necessary to backup S3?

#13

Post by windsurfer » Mon, Sep 14, 2009, 3:13 PM UTC

Standard response from anyone: Backup everything, just in case

http://tvtropes.org/pmwiki/pmwiki.php/Main/CrazyPrepared

Re: Ask HN: Is it necessary to backup S3?

#14

Post by mgorsuch » Mon, Sep 14, 2009, 3:15 PM UTC

You should certainly backup your data. While the engineers at Amazon are certainly among the smartest, they are not infallible. Things do fail from time to time.

I lost 1TB of data several months ago due to some backend issues with EBS and S3. Fortunately for me, it was just a backup of a backup of a backup. ;-)

Re: Ask HN: Is it necessary to backup S3?

#15

Post by mgorsuch » Mon, Sep 14, 2009, 3:17 PM UTC

mgorsuch wrote: post #14

You should certainly backup your data. While the engineers at Amazon are certainly among the smartest, they are not infallible. Things do fail from time to time. I lost 1TB of data several months ago due to some backend issues with EBS and S3. Fortunately for me, it was just a backup of a backup of a backup. ;-)

It's also worth pointing out that this might have been more of a failure of EBS (elastic block storage, an abstraction over S3) than with native S3 buckets.

Ultimately, my EBS device become unusable by any operating system, and Amazon support stated that the data was lost due to several backend systems failing.

Re: Ask HN: Is it necessary to backup S3?

#16

Post by kierank » Mon, Sep 14, 2009, 3:19 PM UTC

Yes, Sometimes the software tools you use can mess up. I lost many production EC2 images because of this unfixed bug in elasticfox:

http://sourceforge.net/tracker/index.php?func=detail&aid...

(basically if you have similarly named images, they'll all get deleted with the "Delete AMI parts and deregister" feature)

Re: Ask HN: Is it necessary to backup S3?

#17

Post by garnaat » Mon, Sep 14, 2009, 3:27 PM UTC

jacquesm wrote: post #2

How would you feel if one day that data was lost ? There are already documented cases of Amazon losing data in S3. The Amazon S3 SLA does not cover data loss at all, only service unavailable situations, which they will cover by crediting you. http://aws.amazon.com/s3-sla/ http://www.datacenterknowledge.com/archives/2007/10/09/amazo... And even if all this was not the case you have a responsibility to your customers y…

I have never seen a documented case of S3 losing data. Please provide references.

I have recommended to some customers that they back up S3 data to the S3 service running in another region. The new export service also provides a way to get physical copies of your data but, depending on how much data you have, it might not be practical.

Re: Ask HN: Is it necessary to backup S3?

#18

Post by aolnerd » Mon, Sep 14, 2009, 3:36 PM UTC

keep multiple snapshots so that you can recover files after you delete them yourself.

#!/bin/sh

AWS_ACCESS_KEY_ID=

AWS_SECRET_ACCESS_KEY=

BUCKET=

DIR=

S3SYNC=/usr/bin/s3sync.rb

DAYS_TO_KEEP_BACKUPS=30

# colons in path confuse s3sync

DATE=$(date +%F_%H-%M-%S)

NEWEST=$(/bin/ls -r $DIR | grep -v current | head -1)

# copy the newest copy of files into a new directory, creating hardlinks instead of duplicate files

cp -al $DIR/$NEWEST/ $DIR/$DATE/

# sync the s3 bucket against the new directory

$S3SYNC --recursive --make-dirs --delete --no-md5 -v $BUCKET: $DIR/$DATE/ 2>&1 | grep -v 'Could not change owner'

# update the "current" symlink link

test -e $DIR/current && rm $DIR/current

ln -sf $DIR/$DATE $DIR/current

# remove snapshots older than DAYS_TO_KEEP_BACKUPS days

find $DIR -maxdepth 1 -type d -mtime +$DAYS_TO_KEEP_BACKUPS -print0 | xargs -0 --no-run-if-empty rm -rv

Re: Ask HN: Is it necessary to backup S3?

#19

Post by jacquesm » Mon, Sep 14, 2009, 3:37 PM UTC

garnaat wrote: post #17

jacquesm wrote: post #2

How would you feel if one day that data was lost ? There are already documented cases of Amazon losing data in S3. The Amazon S3 SLA does not cover data loss at all, only service unavailable situations, which they will cover by crediting you. http://aws.amazon.com/s3-sla/ http://www.datacenterknowledge.com/archives/2007/10/09/amazo... And even if all this was not the case you have a responsibility to your customers y…

I have never seen a documented case of S3 losing data. Please provide references. I have recommended to some customers that they back up S3 data to the S3 service running in another region. The new export service also provides a way to get physical copies of your data but, depending on how much data you have, it might not be practical.

http://developer.amazonwebservices.com/connect/thread.jspa?t...

Do you need more or do you think that is enough like that ?

We've been here before by the way:

http://news.ycombinator.com/item?id=528541

Re: Ask HN: Is it necessary to backup S3?

#20

Post by idlewords » Mon, Sep 14, 2009, 4:08 PM UTC

quellhorst wrote: post #7

If you are hacked, someone could get your S3 credentials and delete your content. You should backup.

It would be wonderful if S3 offered a write-only, no-overwrite mode so you could upload stuff from servers without storing credentials.