toasters August 2000

toasters@lists.teaparty.net

152 participants
177 discussions

RE: Snapshots and Oracle
by Yarmas, Tom 17 Aug '00

17 Aug '00

That's right. The SCN corresponds to the "The checkpoint, i.e., a record indicating the point in the redo log such that all database changes prior to this point have been saved in the datafiles." The part of my post that you included in your message was cut and pasted from the Oracle documentation. The TR produced by NetApp is intended as an example of how to use Snapshots to backup an Oracle database. It is certainly important that any DBA/SA familiarize themselves with the Oracle Backup and Recovery Guide, and fully understand what needs to be backed up in order to be able to recover from various failures as they relate to an Oracle Instance. It is also important that recovery scenarios be practiced. The Snapshot technology simply gives the DBA a virtual online copy of the datafiles that are stored on the Filer. There are many parts of the Oracle database, and many variations on which parts any individual might store on a Filer for any given Oracle Instance. It is important that no parts that are required for recovery are forgotten during a backup. -tom > -----Original Message----- > From: Gustavo Chaves [mailto:gustavo@cpqd.com.br] > Sent: Wednesday, August 16, 2000 8:02 AM > To: toasters(a)mathworks.com > Subject: Re: Snapshots and Oracle > > > >>>>> "Yarmas" == Yarmas, Tom <Tom.Yarmas(a)netapp.com> writes: > > Yarmas> The control file contains: The database name. The timestamp > Yarmas> of database creation. The names of the database's datafiles > Yarmas> and online and archived redo log files. The checkpoint, > Yarmas> i.e., a record indicating the point in the redo log such > Yarmas> that all database changes prior to this point have been > Yarmas> saved in the datafiles. Information on backups (when using > Yarmas> the Recovery Manager utility). > > I'm no expert but W. Curtis Preston tells on page 459 of his book > 'UNIX Backup & Recovery' (from O'Reilly) that Oracle's control files > keep something called an SCN (System Change Number) for each database > object. In particular, whenever a datafile is modified its SCN is > incremented in it and in the control files. From this I gather that > control files are changed after every database change, which means we > *must* back them up whenever we backup the database. > > Gustavo. >

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Re: Configuring Netbackup for NDMP 3.2
by Steve Kappel 17 Aug '00

17 Aug '00

Oye Akintan wrote: >I used tsdtest -r and I got a different kind of error >it says: >scsi command failed >Sense key: Illegal Request (0x5) >Invalid move attempted (ASC 0x24, ASCQ 0x0) > >The tape is set to target 6 on SCSI id 0 on netapp so i set the command > >I'm guessing something is wrong with this setting. How can I resolve this ? Someone here said that these DLT4700 stackers always have the drive on LUN 0 and the robotic control on LUN 1. Try set_ndmp_attr -robot servername spt0 0 6 1 __________________________________________________________________________ Steve Kappel steve.kappel(a)veritas.com VERITAS Software steve.kappel(a)iname.com (Personal)

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Re: Configuring Netbackup for NDMP 3.2
by Steve Kappel 17 Aug '00

17 Aug '00

>Oye Akintan wrote: >>We have a F230 running Data Ontap 5.2.3 with a Quantum DLT4700 directly >>attached to it. I'm running Netbackup for Veritas 3.2 and Netbackup for >>NDMP 3.2. I've installed jumbo patch 0820413. I'm having problem >>configuring the storage device. I ran the command set_ndmp_attr -robot . >>The sys admin guide says to test it using tldtest -r servername:spt0 but >>when I ran this command, the mode sense failed with the following error: >> >>mode_sense failed, CHECK CONDITION >>sense key = 0x5, asc = 0x24, ascq = 0x0, INVALID FIELD IN CDB >> Can anyone tell me what I can do to fix it ? > >Is this a standalone drive? If so, then there is no robot to configure. >tldtest -r tests the robot. I was just reminded (thanks Bill Roth @ NetApp) that DLT4700 drives only work in stackers. In NetBackup that is robot type TSD, not TLD. So the test program would be tsdtest. __________________________________________________________________________ Steve Kappel steve.kappel(a)veritas.com VERITAS Software steve.kappel(a)iname.com (Personal)

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Re: Snapshots and Oracle
by Gustavo Chaves 16 Aug '00

16 Aug '00

>>>>> "Yarmas" == Yarmas, Tom <Tom.Yarmas(a)netapp.com> writes: Yarmas> The control file contains: The database name. The timestamp Yarmas> of database creation. The names of the database's datafiles Yarmas> and online and archived redo log files. The checkpoint, Yarmas> i.e., a record indicating the point in the redo log such Yarmas> that all database changes prior to this point have been Yarmas> saved in the datafiles. Information on backups (when using Yarmas> the Recovery Manager utility). I'm no expert but W. Curtis Preston tells on page 459 of his book 'UNIX Backup & Recovery' (from O'Reilly) that Oracle's control files keep something called an SCN (System Change Number) for each database object. In particular, whenever a datafile is modified its SCN is incremented in it and in the control files. From this I gather that control files are changed after every database change, which means we *must* back them up whenever we backup the database. Gustavo.

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RE: Filer storage for databases, seriously? (Was: Re: NetApp ques tions)
by Sims, Aaron 16 Aug '00

16 Aug '00

You're right about one thing... all things are not equal. You raised some good points along the way... see below for my annotations. > -----Original Message----- > From: Brian Tao [mailto:taob@risc.org] > Sent: Thursday, August 10, 2000 2:33 PM > To: Pesce, Nicholas (FUSA) > Cc: keith(a)netapp.com; toasters(a)mathworks.com > Subject: RE: Filer storage for databases, seriously? (Was: Re: NetApp > ques tions) > > > On Wed, 9 Aug 2000, Pesce, Nicholas (FUSA) wrote: > > > > I'm sorry Keith. But I've heard this argument before. NFS versus > > Direct attatch storage? I'm going to have to vote for a good direct > > attach solution. Why? > > > > NFS and CIFS have huge overhead. > > Sure, as someone else mentioned, all other things being equal, > direct-attach storage is faster than network-attached storage. The > logic (which I've argued before as well) is simple: a NAS box talks > to its drives as DAS. Thus, the DAS must necessarily be "faster" > (yeah, a vague term). For example, setting caching aside, it is not > possible for a filer to pump 50MB/s of data to an NFS client if it can > only read 30MB/s off its own drives. One thing to remember in regards to caching... when you request a block on disk, your local OS (with direct attach storage) will read that block and read ahead several more blocks. Those read-ahead blocks will be transferred via your fibre channel, even if they aren't used by your application. The filer on the other hand will do the same read-ahead, but it will only transmit the block that was requested. If the application asks for the next block, then both have that block in memory. Now, in a database environment where blocks are very randomly placed within a filesystem, this read-ahead via direct attach storage is going to kill the efficiency of the bandwidth to your storage, and that's your OS's fault. Whereas with a filer, you can turn off read-ahead within the filer to minimize the work it does. > > However, all things are not equal, at least in benchmarks that are > possible in the real world. Yes, NFS and CIFS add overhead compared > to SCSI-over-FibreChannel or what have you. However, that is offset > by an optimized OS (Data ONTAP), by an efficient filesystem (WAFL), by > read and write caching, by an optimized TCP/IP stack, etc. If you > could port all that and run it to DAS, then you might have a fair > comparison. > > > I think I would like to see a test where the Disk sizes and number > > were similar, I sincerely doubt the Netapp would do as well. > > Depends on the application, of course, but I've been surprised > many times in the past when I thought for sure the Netapp would not be > able to keep up. I have a 4x450-MHz E420R with a VxVM RAID-0 device, > spread over 16 50GB 7200 rpm drives on two U2SCSI buses. The server > also has a Gigabit Ethernet connection to an F740 with one shelf of > 36GB 10000 rpm drives (5 data, 1 parity, 1 spare). The local > filesystem is vxfs, mounted with delaylog and the largest allowable > log area. > > I ran a few filesystem replication and backup/restore tests (this > is our central tape server). The local filesystem handily beat the > Netapp doing large sequential reads and writes (120MB/sec vs. > 22MB/sec)... no surprise there. File deletions were a little closer > (~2500 unlinks/sec on vxfs, ~2000 unlinks/sec on the Netapp). In all > other tests, the Netapp was as fast or faster (sometimes by a large > margin) than local filesystem. The Netapp seems to especially shine > when you have multiple processes reading and writing to all points on > the filesystem. vxfs does not appear to handle it as gracefully with > dozens or hundreds of concurrent access requests. This is an apples to oranges test. Sure, streaming to/from RAID0 will always kick ass. However, who really runs RAID0 these days??? (I'm sure there's about <.1% of applications where RAID0 is suitable, because the data is not critical) RAID 0+1 might be a slightly better comparison since the filer doesn't have a RAID0 mode. > I re-ran some of the same tests with a Veritas RAID-5 volume (to > be fair to the Netapp), but I stopped after the first couple. There > is no contest at that point. Veritas software RAID-5 is dog-slow (I > think I saw bursts of 8MB/sec sequential writes). Turn on a Veritas > snapshot, and writes to the snapped filesystem go even further into > the toilet. The performance degradation is cumulative with the number > of snapshots. There is no such penalty on the Netapp. Ok, this is apples to apples. > One caveat I should mention, since it bit us in the past: file > locking performance. We have one application that, when running on > the same type of hardware as above (E420R with those drives), spews > forth 150,000 syscalls per second, according to Solaris' "vmstat". > 80% of those calls are fcntl() locks/unlocks to various database files > on disk. Poor programming practice aside, this application runs very > slowly over NFS. It simply cannot match in-kernel file locking when > you're dealing with a local filesystem. Besides that one exceptional > application, we run Netapps for everything else (including Oracle). Ok, given the environment you just described, you could enable a undocumented feature within the solaris mount_nfs command, 'llock'. This tells the NFS client that he shouldn't use NLM to do file locking, I'll just do it locally. This will essentially give you in-kernel locking. The caveat here is that you can't share the filesystem with other clients, but you can't do that with today's direct attach storage either. I usually recommend using the llock option in a Solaris/Oracle/filer environment. Aaron

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RE: Snapshots and Oracle
by Yarmas, Tom 15 Aug '00

15 Aug '00

The control file contains: The database name. The timestamp of database creation. The names of the database's datafiles and online and archived redo log files. The checkpoint, i.e., a record indicating the point in the redo log such that all database changes prior to this point have been saved in the datafiles. Information on backups (when using the Recovery Manager utility). You should certainly backup the control file after any structural change to the database (i.e. addition of data or log files). Additionally, as part of a "normal" backup, I would issue - alter system archivelog current; This would cause a log switch, as well as archive the current redo log and all unarchived redo logs. I would then issue - alter system backup controlfile to 'PATH-TO-FILER' reuse; That way I would have a current copy of the control file included in the snapshot. I might also issue - alter system backup controlfile to trace, as well as copy the parameter file (init.ora and config.ora) to the Filer so I have them as part of the snapshot as well. Finally, I would not exclude any tablespaces from the alter tablespace begin backup. I figure if the snapshot is going to capture the datafiles anyway, I might as well have them in hot backup mode so they are valid for backup. And yes, I would also move the commands that manage the snapshots (except of course the creation of the snapshot) to before the tablespaces are actually put in hot backup mode. No doubt, the Oracle Backup and Recovery Guide is indispensable. You should fully understand what needs to be backed up and you should test your restore procedures. > -----Original Message----- > From: X X [mailto:gynt@post.com] > Sent: Tuesday, August 15, 2000 4:57 AM > To: toasters(a)mathworks.com > Subject: Re: Snapshots and Oracle > > > >Treat the control files just as you would any other critical DB > >file. When you shut your DB down and snapshot it, make a backup > >copy of the control files also. Control files only change when > >you do structural changes to your database, and thus must be > >backed up only then. Of course that is best case, just > >incorporate control files into your normal backups. As for redo > >logs they do not nee to be backed up. In fact you really cannot > >use them for anything other than instance recovery when you have > >the database crash. If you do a clean shutdown there is no data > >in these redo's. It gets flushed to disk during the shutdown. > > Shure! but I was talking about hot-backups. From what I under- > stand the control-file also contains info about the logfiles, > so it is important when and how it is copied. > > Should it not be a "ALTER SYSTEM SWITCH LOGFILE;" (that also > updates the control file) and then a "ALTER DATABASE BACKUP > CONTROLFILE TO '/SomeDirectory/SomeFileName.bkp' REUSE;" > before the snapshot is taken?? > > Also to minimize the time that the database is in backup > mode I would move all the "rsh -l root filer4 snap ..." > commands in dohotbackup.sh to a line before the dobegin.sql > script is run. > > /Gynt > > > ______________________________________________ > FREE Personalized Email at Mail.com > Sign up at http://www.mail.com/?sr=signup >

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Virus Scan
by Shaw, Kevin 15 Aug '00

15 Aug '00

Anyone virus scanning their filers from a unix system? What S/W is being used? Any major problems? Thanks in advance. Kevin

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Quick question
by kelvin tooth 15 Aug '00

15 Aug '00

Someone has just come up to me and asked me: "What is the maximum number of files on a fully populated (disk wise) F760?" I don't (sorry) know the volume configuration specified. have you guys got any ideas? I couldn't find the maximum value of the maxfiles command documented in the now site, or on my piece of paper from NTAP201/2. regards, Kelvin Tooth

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RE: Virus Scanning
by Lyons, Jim 15 Aug '00

15 Aug '00

Am using a pretty crude couple of batch files to do a dir against the volume, pipe that to a file. Then iterate through the file and scan each dir that is not named ~snapshot. Need to use the /NORESULTS switch on the navwnt command so that processing does not stop when a dialog is presented to the screen. We tried NAV corp edition 7.xx, but it lacked the email notification feature (you have to buy a separate product, Symantec System Center, to do this). It also did not do scheduled scans for some reason on our NT server, but would from a workstation. Also hit the known bug that you cannot start a manual scan as long as the service is running. Also note that in NAV5, the exclusions work, but not as I would like (thus the batch file). Even though a directory is excluded, NAV still reads each file in the directory, but does not scan it. In Corp edition 7.xx, the exclusions work properly, but we had so many other issues with it that we went back to NAV5. rgds, Jim -----Original Message----- From: Nail, Larry Sent: Friday, August 04, 2000 5:59 PM To: Lyons, Jim; 'toasters(a)mathworks.com' Subject: RE: Virus Scanning Jim, We're currently using NAV5 to do this however, we're having to move to Corp. Edition 7.02 because of Windoze 2000, so I'm looking for another command line driven virus scanner that I can use. On a side note, what are you using to exclude snapshots. My efforts to put ~snapshot in the exclusions have been futile. Regards, Larry -----Original Message----- From: Lyons, Jim Sent: Friday, August 04, 2000 3:58 PM To: Nail, Larry; 'toasters(a)mathworks.com' Subject: RE: Virus Scanning Larry, we are using NAV50 called from a scheduled nightly batch file in order to skip the snapshot directories. Jim -----Original Message----- From: Nail, Larry Sent: Friday, August 04, 2000 2:53 PM To: 'toasters(a)mathworks.com' Subject: Virus Scanning Just curious if anyone is running a virus scanner against filers for CIFS? ______________________________________ Lawrence D. Nail Microsoft Certified Systems Engineer Senior NT Systems Administrator MSPD NT Systems Engineering Mixed Signal Products http://www1.msp.sc.ti.com/nail/ <http://www1.msp.sc.ti.com/nail/>

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Re: Snapshots and Oracle
by X X 15 Aug '00

15 Aug '00

>Treat the control files just as you would any other critical DB >file. When you shut your DB down and snapshot it, make a backup >copy of the control files also. Control files only change when >you do structural changes to your database, and thus must be >backed up only then. Of course that is best case, just >incorporate control files into your normal backups. As for redo >logs they do not nee to be backed up. In fact you really cannot >use them for anything other than instance recovery when you have >the database crash. If you do a clean shutdown there is no data >in these redo's. It gets flushed to disk during the shutdown. Shure! but I was talking about hot-backups. From what I under- stand the control-file also contains info about the logfiles, so it is important when and how it is copied. Should it not be a "ALTER SYSTEM SWITCH LOGFILE;" (that also updates the control file) and then a "ALTER DATABASE BACKUP CONTROLFILE TO '/SomeDirectory/SomeFileName.bkp' REUSE;" before the snapshot is taken?? Also to minimize the time that the database is in backup mode I would move all the "rsh -l root filer4 snap ..." commands in dohotbackup.sh to a line before the dobegin.sql script is run. /Gynt ______________________________________________ FREE Personalized Email at Mail.com Sign up at http://www.mail.com/?sr=signup

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toasters August 2000