Hi there,

Do you have any experience with running a dbfarm over iSCSI?

We have tried to use the NAS in our 1Gbit LAN for our largish daily experiments with MonetDB. It's a very handy setup and seems more suited than NFS.

It seems to achieve reasonable performance, but we get quite regularly (though not predictably for now) commit failures during a rather long ETL.

We do not get such commit failures when the same db and ETL are run on a local disk.

Excerpt from merovingian.log (Jul2015-SP1):

2015-11-24 11:52:37 ERR trec01[19110]: !ERROR: bm_subcommit: commit failed

2015-11-24 11:52:37 ERR trec01[19110]: !ERROR: log_tend: write failed

2015-11-24 11:52:37 ERR trec01[19110]: !FATAL: 40000!COMMIT: transation commit failed (perhaps your disk is full?) exiting (kernel error: !ERROR: GDKsave: error on: name=07/717, ext=theap, mode=1

2015-11-24 11:52:37 ERR trec01[19110]: !OS: Input/output error

2015-11-24 11:52:37 ERR trec01[19110]: )

The disk is most definitely not full, 1.5 TB available (the same works on a local disk with less space available).

It looks like iSCSI is the problem (which works perfectly except these random failures).

Can you think of any reason why iSCSI could could fail where a real local block device would not?

iscsi client (where MonetDB runs): libiscsi 1.11.0

iscsi storage (where the dbfarm is stored): iscsid 2.0-871

The iSCSI LUN is created as regular file with thin provisioning (a file that dynamically grows on the NAS). We haven't tried yet with a fixed-size block-level LUN (trying this today anyway)

Hoping someone can have an idea already.

Roberto