Dumb IP Question
Tom Duerbusch [EMAIL PROTECTED] wrote:
From my understanding, when a client connected to the server stack at a
particular port, that port is tied up and no one else can connect to
it.
If I remember correctly, when you FTP to port 21, the FTP server
responses with another port that you should use for the rest of the FTP
session. This keeps port 21 from being tied up during long FTP
sessions. Right?
As far as TCP is concerned, a connection is identified by the
{source address, source port, destination address, destination port}
combination. When a packet comes in, that is what is used to find
the appropriate destination. Since TCP is a stream protocol,
the packets are processed by TCP, retransmissions are requested,
and data is delivered only after it is back in stream format.
Boundaries between requests to TCP don't necessarily generate
separate TCP packets, and packet boundaries aren't seen on
by receiving program.
UDP usually only processes the {destination address, destination port}
combination. Some servers will decode the source address, source
port, but it is the responsibility of the receiving program.
Many stateless servers can handle UDP without a subtask for
each client, just replying to each request. Data is delivered
preserving packet boundaries.
Under unix, programs accepting a TCP connection usually fork()
to create a subtask to handle the connection. It might be that
new requests that come in before the fork() get the busy signal.
Most print servers boxes can only handle one connection at a time,
and will refuse any additional connections. That is not a TCP
limitation, but a higher level protocol limitation. Sendmail,
I believe, also refuses connections when too many are already
open to avoid overloading the machine.
-- glen
vm alternat userid support
Is there any command or instruction that a worker machine can use to obtain the userid that it has been assigned by the set alternate user ( diagd4) The question is who do I work for? Regards Mats Westlund
Re: 3390 Huge Volumes
I greatly appreciate all the information everyone provided. Thank you. Cecelia Dusha
Re: vm alternat userid support
Get the LCLQRY package fromp VM's download lib and you'll get a CP Q ALTUSER command. Part of my RxServer package is a DIAGD4 MODULE to set the alternate userid. Kris, IBM Belgium, VM customer support Westlund, Mats (Mainframe servers) [EMAIL PROTECTED] Sent by: The IBM z/VM Operating System IBMVM@LISTSERV.UARK.EDU 2006-05-18 09:41 Please respond to The IBM z/VM Operating System To IBMVM@LISTSERV.UARK.EDU cc Subject vm alternat userid support Is there any command or instruction that a worker machine can use to obtain the userid that it has been assigned by the set alternate user ( diagd4) The question is who do I work for? Regards Mats Westlund
Re: vm alternat userid support
On Thursday, 05/18/2006 at 09:41 ZE2, Westlund, Mats (Mainframe servers) [EMAIL PROTECTED] wrote: Is there any command or instruction that a worker machine can use to obtain the userid that it has been assigned by the set alternate user ( diagd4) The question is who do I work for? No, though a nice little home-grown diagnose could retrieve it from VMDALTID in the VMDBK. That and the AUTOLOGged-by user would be good additions to diag 0x260. I'll see what I can do. (Kris' LCLQRY is a good start in the meantime.) [There is a kludge: you can create a spool file and look at the ORIGIN...it will have the alternate id. Eeeew.] Alan Altmark z/VM Development IBM Endicott
Re: vm alternat userid support
On Thu, 18 May 2006 09:48:10 -0400 Alan Altmark said: On Thursday, 05/18/2006 at 09:41 ZE2, Westlund, Mats (Mainframe servers) [EMAIL PROTECTED] wrote: Is there any command or instruction that a worker machine can use to obtain the userid that it has been assigned by the set alternate user ( diagd4) The question is who do I work for? No, though a nice little home-grown diagnose could retrieve it from VMDALTID in the VMDBK. That and the AUTOLOGged-by user would be good additions to diag 0x260. I'll see what I can do. (Kris' LCLQRY is a good start in the meantime.) [There is a kludge: you can create a spool file and look at the ORIGIN...it will have the alternate id. Eeeew.] Another would be to create a lock on an SFS access directory, and then query the lock create lock profile exec a share session query lock profile exec a will return Directory = fp:fs. Filename Filetype Fm TypeUserid Lock Duration PROFILE EXEC A1 BASEaltuserSHARE SESSION where fp is the filepool, fs is the filesystem and altuser is the D4 user There are other SFS tricks, like accessing a dircontrol directory and looking at the accessors, etc. Alan Altmark z/VM Development IBM Endicott /ahw
Re: VSWITCH and EtherChannel...can it be done?
On Wed, 17 May 2006 20:27:49 -0400, David Boyes [EMAIL PROTECTED] wrote: If not, how would you go about load balancing a couple of OSAs without running any routing protocols under VM? Incoming traffic can be balanced using equal-cost routing in the network devices. Outbound load balancing requires a routing daemon, but you could define a null interface and distribute routes only to the null interface and the local stack, which would let you use VIPA but not impact the network at large by sending routing updates. Took me a sec to catch your meaning here, but I finally twigged. I'll ju st settle for the incoming balancing for now as we really don't want to run any routing under VM. But, if push come to shove, I do like your idea of at least keeping the routing WITHIN VM. Pretty nifty. Leland
MAC Address
We are running z/VM 3.1 and 5.1 on an IBM z/890 with z/VM TCP/IP 510. We have 2 OSA cards with 2 ports each. My question, how do we find the MAC address from this system so that we can obtain PKI certificates? Ira Thompson 703-614-5677
Re: MAC Address
Hello Ira, Have done a NETSTAT ARP your IP address? Ed Martin Aultman Health Foundation 330-588-4723 [EMAIL PROTECTED] ext. 40441 -Original Message- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Thompson, Ira CTR WHS/ITMD/ZEN Sent: Thursday, May 18, 2006 1:10 PM To: IBMVM@LISTSERV.UARK.EDU Subject: MAC Address We are running z/VM 3.1 and 5.1 on an IBM z/890 with z/VM TCP/IP 510. We have 2 OSA cards with 2 ports each. My question, how do we find the MAC address from this system so that we can obtain PKI certificates? Ira Thompson 703-614-5677
Re: Emulated tape/ECKD disk
Dave ... Is this a product SNA or some would deliver? Or are you proposing that IBM step up to it? -- R; On Tue, 16 May 2006, David Boyes wrote: Several people asked off-list just what I had in mind wrt to emulated tape and disk over SCSI/FCP. Attached below is a draft of what I've got so far. If this is something you could support (and your company would support), please let me know. -- db SCSI Support Extension Proposal Desired Action: Complete the emulated device over SCSI/FCP support introduced in z/VM to include both ECKD disk emulation on SCSI/FCP and emulation of channel-attached tape to generic SCSI/FCP tape devices. If possible, the tape emulation should also support a remote tape server option, mapping the emulated device to a user specified process over a network connection. Business Justification: 1) In many small to medium-sized shops, the amount of money available to invest in mainframe technology is limited compared to the funding accessible to the open systems environment. Often, significant disk and tape resources are duplicated or over-provisioned in the open systems environment, but are not accessible for reuse in the mainframe environment due to the requirement for specialized interfaces and separate management to support mainframe-specific environments. Enabling software emulation of mainframe devices on top of a generic SCSI/FCP infrastructure would allow System z infrastructure to leverage these existing enterprise infrastructure investments directly, improving the TCO argument for maintaining System z-based infrastructure. (It is clearly acknowledged that software emulation has a performance impact compared to native ECKD over FICON. In many cases, this performance vs cost tradeoff is acceptable in that the development curve for device and storage area network performance often offsets the disadvantage within a relatively short period of time, and the cost savings is often an acceptable tradeoff vs execution time delays due to longer I/O delays. ) 2) Even given the recent price reductions for the System z BC and EC machines, in some cases, the cost differential to implement separate disk for a System z environment (or add specialized interfaces to support FICON attachment of an existing disk array) is such that disk pricing is a deciding factor to preserve a System z environment. Similarly, environmental issues (floor space, power consumption, heat dissipation) may dictate that additional disk units to support only a single platform argue against retaining the System z solution as a difficult to interoperate with solution. 3) Additional disk volume formats and attachment methods complicate storage management discipline, adding additional training costs for storage administrators and possibly additional costs for software implementation to manage the FICON-attached arrays (not all vendors support FICON-attached volumes in their basic management software, but market that support as a enhanced feature). This increase in complexity further impacts the ROI and TCO of the System z solution. 4) Currently, only VSE, Linux and VM fully support FBA DASD. We are aware of work being done to z/OS to tolerate FBA disk, but until this work is completed, ECKD disk is required. If IBM is to open up additional market opportunity for z/OS or other ECKD-only systems in the short term, ECKD emulation is necessary to open those opportunities. It is important to note that ECKD emulation on SCSI disk has been done in the past for the P/390, R/390, and Multiprise systems, and it is clear from a cursory examination of the z/VM EDEV SCSI stack that these previous attempts could be used as a starting point to provide this type of emulated function. 5) With regard to tape, currently the largest supported FICON-attached tape unit supports a 40G uncompressed volume. Open systems tape units regularly support 200G or greater volume sizes. With the dramatic increase in data volumes, the inability of System z to access these commonplace devices argues significanly against adoption of a System z based solution in place of a Intel or other platform solution. 6) Similar to the ECKD disk emulation code mentioned above, tape emulation code for 3420 and 3480/90 tape over SCSI also exists, and offers direct support for all System z operating systems currently supporting tape without additional development. Emulated tape devices could easily be mapped to higher-capacity SCSI devices, providing direct benefit for backup/DR and data exchange purposes. 7) Adding ECKD and tape emulation would allow dramatic simplification of software distribution for System z operating systems, allowing applications to be directly supplied as disk images on inexpensive
Re: Emulated tape/ECKD disk
Is this a product SNA or some would deliver? Or are you proposing that IBM step up to it? We'd be happy to do the coding as subcontractors, but long-term, this has to be a IBM-embraced effort to be successful. This really needs to be core VM function. -- db
