Hi Rick, hi all,
thanks for your responses so far.
To be a little more precise: I meant your environment behind a SAN
Gateway/Bridge, not natively attached zfcp devices.
With kind regards
Thorsten Diehl
System Test Linux on System z
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter
Geschaeftsfuehrung: Erich Baier
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294
Richard Troth schrieb am 07.07.2009 16:32:
We use SAN attached disk at my shop. I should refrain from indicating
which vendor (in this context) because I should not convey some kind
endorsement. We do not presently use SAN attached tape nor CD or DVD.
The devices are connected via switched fabric (yet another vendor used
for the switches), both production and dev/test. The production
volumes are replicated to secondary copies for disaster recovery.
(dev/test vols are not replicated) The production volumes are in
demand 24x7 so we lean heavily on the dual path capability: When one
path is taken down either for service or because of an error the other
carries the traffic. (This is a customer-facing workload.)
Once things are configured, they run without problems.
If you are using SLES 10, you will want to be on SP2 for improved SCSI
stack behavior. We encountered periodic filesystem errors resulting
in some filesystems being switched read-only (to prevent damage) on
both VMware hosted i386 and x86_64 and z/VM hosted s390x Linux guests
with SLES 10 SP1. (I cannot report on this problem on RHEL. Not
enough data there.)
I STRONGLY RECOMMEND that people considering SAN look into EDEV where
z/VM will present SAN disks as 9336 equivalent FBA DASD. This allows
the storage to be managed via the CP Directory, so that your SAN
backed storage can be managed as effectively as your ECKD backed
storage. We could not take this route initially because at the time
EDEV lacked dynamic path controls (presently an open req with IBM).
As a result, we plug our Linux guests directly into the fabric. This
has some value points, notably reduced I/O overhead, but presents a
serious storage management burden.
Vendors: Mixed IPL from installation media would be nice. What I mean
is, if a disk is attached via SAN, support the SAN IPL method,
obviously. But if a disk is attached via EDEV, also support the DASD
IPL method. The two should coexist quite well on any CD or DVD.
Clearly the 'zipl' bootstrap already contains everything that is
needed. Using an ISO 9660 filesystem gives ample room for the
bootstrap.
-- Rick; <><
On Tue, Jul 7, 2009 at 09:34, Thorsten Diehl<tdi...@linux.vnet.ibm.com> wrote:
Hi all,
I'm curious and would like to know, who is using zfcp attached SCSI
devices.
If you like, please answer the following questions:
1. Type (Manufacturer/Model) of the SAN Gateway/Bridge
2. Category, Type and number of attached SCSI devices (e.g. SCSI Tapes,
DVD drives, disks)
3. Your experience with the SAN gateway (configuration, reliability)
4. How often do you use the attached devices (daily, rarely, ....) and
for which purpose
Authentic example:
1. IBM 2108-G07 SAN gateway (aka PATHLIGHT)
2. 1x SCSI-DVD-ROM, 1x IDE-DVD-Multiburner via IDE-SCSI-Converter, 1x
4mm DDS3 SCSI Tape
3. easy to configure, runs without problems
4. regularly, for system z Linux installations via SCSI DVD (no ftp
server required).
Thanks in advance for your response!
--
With kind regards
Thorsten Diehl
System Test Linux on System z
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter
Geschaeftsfuehrung: Erich Baier
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294
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