Re: backup postgresql with snapshot AWS - Mailing list pgsql-admin

Hi

pgpdbabe@elaawddbad00:/pgsql/pdbabe/data/pdbabe/pg_tblspc> df /pgsql/pdbabe/* | sort -u
/dev/mapper/pdbabe_2-lv_archive 102180192 60291608  36698136  63% /pgsql/pdbabe/archive
/dev/mapper/pdbabe_2-lv_staging  19610300  4810764  13803392  26% /pgsql/pdbabe/staging
/dev/mapper/pdbabe-lv_admin      10321208   241396   9555524   3% /pgsql/pdbabe/admin
/dev/mapper/pdbabe-lv_data       10321208   177628   9619292   2% /pgsql/pdbabe/data
/dev/mapper/pdbabe-lv_tsdata    258030980 45415480 199508300  19% /pgsql/pdbabe/tsdata
/dev/mapper/pdbabe-lv_tsindex   103212320   192268  97777172   1% /pgsql/pdbabe/tsindex
/dev/mapper/pdbabe-lv_tstemp     51606140   184268  48800432   1% /pgsql/pdbabe/tstemp
/dev/mapper/pdbabe-lv_xlog       51606140 16259012  32725688  34% /pgsql/pdbabe/xlog
Filesystem                      1K-blocks     Used Available Use% Mounted on

elaawddbad00:~ # pvs
  PV         VG       Fmt  Attr PSize   PFree
  /dev/sda2  system   lvm2 a--   50.00g 10.55g
  /dev/xvdc  pdbabe   lvm2 a--  510.00g 40.00g
  /dev/xvdd  pdbabe_2 lvm2 a--  120.00g  2.00g

Thanks & Regards
Gabriele

> Il 23 gennaio 2018 alle 12.08 Achilleas Mantzios <achill@matrix.gatewaynet.com> ha scritto:
>
>
> On 23/01/2018 13:02, flumbador@virgilio.it wrote:
> > Hi
> > I confirm that we have only one EBS volume, but Postgresql spans multiple filesystem on that EBS volume.
> > Filesystems are:
> >
> > /pgsql/pdbabe/data      => PGDATA
> > /pgsql/pdbabe/tsdata    => Tablespace Data
> > /pgsql/pdbabe/tsindex   => Tablespace Index
> > /pgsql/pdbabe/tstemp    => Tablespace temporary
> > /pgsql/pdbabe/xlog      => pg_xlog
>
> filesystem != directory. Do a
> % df /pgsql/pdbabe/* | sort -u
> to show you all filesystems involved. Might be only one.
>
> >
> > But all on the same EBS Volume.
> > Does snapshot work fine in this scenario?
> >
> > Thanks & Regards
> > Gabriele
> >
> >> Il 19 gennaio 2018 alle 20.39 Rui DeSousa <rui.desousa@icloud.com> ha scritto:
> >>
> >>
> >>
> >>> IMHO the more you intertwine things you cannot be certain of because they operate outside of your particular VM's
spacewith a process that relies on them the more you are risking finding out that your assumptions are wrong the hard
way. You *shouldn't* get bit by this in a well-designed cloud or cluster system but that's not an acceptable word to
describethe expected results when it's important. 
> >> One needs to understand their technology stack. You need to know where your data is after a sync() call… is it
cachedin the controller, some other application layer, or safely on disk? You also need to understand the relationship
betweenluns, volume managers, and filesystems and where your atomic operation are in your setup. 
> >>
> >> i.e. If the filesystem spans multiple EBS volumes then you can’t use EBS snapshots otherwise you end up with a
corruptedfilesystem/database; however, if you use one filesystem per EBS volume then EBS snapshots work fine.  Amazon’s
ownRDS service uses EBS snapshots for backups. 
>
>
> --
> Achilleas Mantzios
> IT DEV Lead
> IT DEPT
> Dynacom Tankers Mgmt
>
>