Tag Archives: Debian

WSFC and iscsitarget: “does not have the inquiry data (SCSI page 83h VPD descriptor) that is required by failover clustering”

Last week whilst trying to get to grips with SQL Server AlwaysOn Failover Clusters, I set up a simple iSCSI target using the “iscsitarget” package as per the Debian docs. However when trying to validate the cluster in WSFC (Windows Server Failover Clustering) the disk checks failed with:

“does not have the inquiry data (SCSI page 83h VPD descriptor) that is required by failover clustering”

This has something to do with the scsiId, which is required by the cluster manager to control volume ownership, being supplied by iscsitarget in a format unsupported by WSFC.

I failed to find a workaround for this and instead switched to using “tgt” to serve the iSCSI targets. I was pushed for time, and couldn’t find a straightforward guide so I’m documenting my steps here.

1) Install tgt:

# apt-get install tgt

2) Enable and start tgt:

# systemctl enable tgt.service
# systemctl start tgt.service

3) Create the iSCSI target(s) and add their backing stores:

# tgtadm --lld iscsi --op new --mode target --tid 1 --targetname iqn.2001-04.com.example:storage.lun1
# tgtadm --lld iscsi --op new --mode logicalunit --tid 1 --lun 1 --backing-store /dev/sdb1

4) Bind the target to listen on all interfaces, with a user account:

# tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
# tgtadm --lld iscsi --op new --mode account --user mssql --password secret
# tgtadm --lld iscsi --op bind --mode account --tid 1 --user mssql

5) Dump the config out into a configuration file:

# tgt-admin --dump > /etc/tgt/conf.d/default.conf
# sed -i -e 's/PLEASE_CORRECT_THE_PASSWORD/secret/' /etc/tgt/conf.d/default.conf

6) Restart to ensure the configuration is picked up.

# systemctl restart tgt.service

Latest megacli 8.07.14 emits message “Configure Adapter Failed” on Perc5i (LSI MegaSAS 8408E)

This morning I came to reconfigure a raid array on an old Dell Perc5i with the LSI MegaRAID CLI tool megacli, and whilst displaying information and removing an old LD appeared to work fine, I was greeted with the following when trying to add a new LD:

# megacli -CfgSpanAdd -r10 -Array0[10:2,10:3] Array1[10:6,10:7] WB RA Direct CachedBadBBU -a0

Adapter 0: Configure Adapter Failed

Exit Code: 0x03

Balls. The “Exit Code: 0x03” is supposed to mean “Input parameters are invalid” (ref), but after a few moments of head scratching and checking my parameters I realised that shouldn’t have been it. The megacli package I’m using comes from the debian repository at hwraid.le-vert.net and always worked in the past. A quick check of their homepage reveals a news item on their front page stating.

2014/01/26 — I just updated megacli to release 8.07.14. Despite it seems to works for me, I’d really appreciate some feedbacks, especially if you’re running a 32 bits system. Please drop me a mail !

So something in the new version isn’t 100% compatible with the Perc5i, I’ll send them an email, but I needed to get the adapter configured and wasn’t too keen to trudge off to the server room. After a quick google search I managed to find a rather old v4.00.16 rpm package in an archive here here and pull out the amd64 binary with rpm2cpio:

$ wget http://docs.avagotech.com/docs-and-downloads/legacy-raid-controllers/legacy-raid-controllers-common-files/4-00-16_Linux_MegaCli.zip
$ unzip 4.00.16_Linux_MegaCli.zip
$ unzip MegaCliLin.zip
$ rpm2cpio MegaCli-4.00.16-1.i386.rpm | cpio -idmv
$ cd opt/MegaRAID/MegaCli/
# ./MegaCli64 -CfgSpanAdd -r10 -Array0[10:2,10:3] Array1[10:6,10:7] WB RA Direct CachedBadBBU -a0

Adapter 0: Created VD 1

Adapter 0: Configured the Adapter!!

Exit Code: 0x00


Edit: 2014/10/16 12:30 The package here here is much more up to date and also works for me with the Perc5i, however it’s not a trustworthy link and I had to do a little more diddling to get it to run on Wheezy:

# apt-get install libsysfs2
# ln -s /lib/x86_64-linux-gnu/libsysfs.so.2.0.1 /lib/x86_64-linux-gnu/libsysfs.so.2.0.2

Spatial capabilities in PostgreSQL with PostGIS

When dealing with geographic data in PostgreSQL, at some point we’re going to want to lookup rows based purely on their location relative to one another.

With smaller volumes of data, we can get away quite easily with just latitude / longitude and some maths, but once we get past a certain point we’re going to want to be able to do index lookups based on distance from a specific location; this is where the PostGIS extension is priceless.

Installing PostGIS on Debian Wheezy

Installing under Debian when PostgreSQL has been installed via the package manager is dead simple. I’m using the 2.1 version packaged for a 9.3 server from the apt.postgresql.org repository, but you should select the package that matches your server version. It’s also possible to install version 1.5 directly from Wheezy main if you don’t want to add other repositories to apt.

$ sudo apt-get install postgresql-9.3-postgis-2.1

This will install the PostGIS contrib modules into the /usr/share/postgresql/9.3/contrib directory rather than the “extension” directory used by most other PostgreSQL packages in Debian.

Some of the machines I look after have PostgreSQL installed from source for various reasons (but mainly because historically packages from Debain weren’t very timely), and these machines require a slightly more lengthy setup process. To compile PostGIS from source we need to install some dependencies, one of which is the development files for the geospatial data abstraction library and these are in the “libgdal-dev” package; however this depends on the “libpq-dev” package which will most likely interfere with our source install. There are two options here; either install the package without it’s dependencies (make a note you’ve done it to avoid future dependency problems), or roll gdal from source:

First we install the required dependencies, these are listed in the PostGIS docs and for my test machine that already has everything required to compile PostgreSQL already these are:

$ sudo apt-get install libgeos-dev libproj-dev libjson-c-dev libjson0-dev

Then install the gdal dev libraries in whichever manner suits:

$ sudo apt-get download libgdal-dev
$ sudo dpkg --force-all -i libgdal-dev_1.9.0-3.1_amd64.deb


$ cd /tmp
$ wget http://download.osgeo.org/gdal/1.10.1/gdal-1.10.1.tar.gz
$ tar xvfz gdal-1.10.1.tar.gz && cd gdal-1.10.1
$ ./configure
$ make
$ sudo make install

Once this is done we can compile and install PostGIS:

$ cd /tmp
$ wget http://download.osgeo.org/postgis/source/postgis-2.1.1.tar.gz
$ tar xvfz postgis-2.1.1.tar.gz && cd postgis-2.1.1
$ ./configure
$ make				
$ sudo make install

Getting started with PostGIS

Now we’ve got PostGIS installed we just need to create the extension in the database:

$ psql -U glyn -d test -c 'CREATE EXTENSION postgis; CREATE EXTENSION postgis_topology;'

OR on and on 9.0 and lower run the sql scripts in the contrib/postgis-2.1 directory:

$ psql -U glyn -d test -f postgis.sql
$ psql -U glyn -d test -f postgis_comments.sql
$ psql -U glyn -d test -f spatial_ref_sys.sql
$ psql -U glyn -d test -f rtpostgis.sql
$ psql -U glyn -d test -f raster_comments.sql
$ psql -U glyn -d test -f topology.sql
$ psql -U glyn -d test -f topology_comments.sql

So let’s generate some data for testing; we create a table called “friends” with 90k rows which stores their locations as latitude and longitude values. Admittedly the distribution in this table won’t be that realistic, but it should suffice for testing:

SELECT b.unnest || ‘ v.’ || generate_series,
CASE WHEN random() > 0.5 THEN ‘Somewhere Else’ ELSE ‘Somewhere’ END,
1.0838637+random()*(CASE WHEN random() > 0.5 THEN -1 ELSE 1 END),
52.7389201+random()*(CASE WHEN random() > 0.5 THEN -1 ELSE 1 END)
FROM generate_series(1,10000)
CROSS JOIN (SELECT unnest(ARRAY[‘White Wonder’,’Colonel K’,’El Loco’,’Count Duckula’,’Leatherhead’,’Barron Greenback’,’Ernest Penfold’,’Professor Heinrich Von Squawkencluck’,’Flying Officer Buggles Pigeon’])) b;

In the scenario where we don’t have PostGIS we can create an sql function to calculate earth distance between two points, but any relative distances will always be an unknown so can’t be indexed:

CREATE OR REPLACE FUNCTION earth_distance_miles(lat1 float, lat2 float, long1 float, long2 float)
RETURNS double precision
‘SELECT 3963.0*acos(sin($1/57.2958)*sin($2/57.2958)+cos($1/57.2958)*cos($2/57.2958)*cos(($4/57.2958)-($3/57.2958)));’

This makes listing out “friends” within a mile pretty easy:

earth_distance_miles(52.7389201, f.latitude, 1.0838637, f.longitude) AS dist_miles
FROM friends f WHERE earth_distance_miles(52.7389201, f.latitude, 1.0838637, f.longitude) <= 1
ORDER BY earth_distance_miles(52.7389201, f.latitude, 1.0838637, f.longitude);

                                           QUERY PLAN
 Sort  (cost=10988.40..11063.40 rows=30000 width=108) (actual time=160.006..160.013 rows=29 loops=1)
   Sort Key: ((3963::double precision * acos(((0.795884736186082::double precision * sin((latitude / 57.2958::double precision))) 
   	+ ((0.605448170123596::double precision * cos((latitude / 57.2958::double precision))) * cos(((longitude / 57.2958::double precision) 
   	- 0.0189169834438126::double precision)))))))
   Sort Method:  quicksort  Memory: 30kB
   ->  Seq Scan on friends f  (cost=0.00..7510.00 rows=30000 width=108) (actual time=19.993..159.930 rows=29 loops=1)
         Filter: ((3963::double precision * acos(((0.795884736186082::double precision * sin((latitude / 57.2958::double precision))) 
         	+ ((0.605448170123596::double precision * cos((latitude / 57.2958::double precision))) 
         	* cos(((longitude / 57.2958::double precision) - 0.0189169834438126::double precision)))))) <= 1::double precision)
 Total runtime: 160.069 ms

Now lets put PostGIS to work and add in an indexed geography column:

ALTER TABLE friends ADD COLUMN geog geography(Point,4326); — SRID 4326 for WGS84
UPDATE friends SET geog = ST_MakePoint(longitude, latitude);

Now let’s try to list out our “friends” within a mile again, this time making use of the PostGIS ST_Distance and ST_DWithin functions:

ST_Distance(f.geog, ST_MakePoint(1.0838637, 52.7389201))/1609 AS dist_miles
FROM friends f WHERE ST_DWithin(f.geog, ST_MakePoint(1.0838637, 52.7389201), 1609)
ORDER BY ST_Distance(f.geog, ST_MakePoint(1.0838637, 52.7389201));

                                           QUERY PLAN
 Sort  (cost=37.90..37.90 rows=1 width=108) (actual time=1.756..1.760 rows=29 loops=1)
   Sort Key: (_st_distance(geog, '0101000020E610000017258D768157F13FB4ED0FEF945E4A40'::geography, 0::double precision, true))
   Sort Method:  quicksort  Memory: 32kB
   ->  Bitmap Heap Scan on friends f  (cost=2.39..37.89 rows=1 width=108) (actual time=0.908..1.684 rows=29 loops=1)
         Recheck Cond: (geog && '0101000020E610000017258D768157F13FB4ED0FEF945E4A40'::geography)
         Filter: (('0101000020E610000017258D768157F13FB4ED0FEF945E4A40'::geography && _st_expand(geog, 1609::double precision)) 
         	AND _st_dwithin(geog, '0101000020E610000017258D768157F13FB4ED0FEF945E4A40'::geography, 1609::double precision, true))
         ->  Bitmap Index Scan on friends_geog_idx  (cost=0.00..2.39 rows=16 width=0) (actual time=0.351..0.351 rows=45 loops=1)
               Index Cond: (geog && '0101000020E610000017258D768157F13FB4ED0FEF945E4A40'::geography)
 Total runtime: 1.821 ms

This shows a marked improvement from a query time of 160.069ms down to 1.821 ms. Obviously our mileage will vary depending on the quantity of data in the table, it’s distribution and just how many rows we want to retrieve.