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by David West 22 Apr '98

22 Apr '98

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Re: Restoring A LOT from snapshot
by sirbruce＠ix.netcom.com 22 Apr '98

22 Apr '98

On 04/22/98 09:37:47 you wrote: > >In message <199804221400.KAA21557(a)prospero.dma.isg.mot.com>, Christoph Doerbeck > writes: >> Solution 1: use 'find' and 'cpio' and transfer all the data back. this >> would appear to require 2x current capacity of the filer to replicate >> all data out of snapshot. if you're using >50%, this method would >> fail. > >If the files in question have been removed, rather than modified, this >will only copy the files that have been removed. On other files, it >will either refuse to copy because it thinks its copying a file onto >itself. It will complain the whole while (slowing things down), but it >will only add the space consumed by the deleted files. At least that's >what happened when I tried it in my home directory. An interesting observation. One example where having the snapshot FSID the same as the filesystem FSID is actually an advantage. :) Bruce

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Restoring A LOT from snapshot
by Christoph Doerbeck 22 Apr '98

22 Apr '98

Question: When restoring from snapshot, is there a method which will not recreate data in the real data area. Example: Random files are removed throughout the filer. We decide to backtrack to Mondays snapshot. We plan to copy everything out of snapshot back to the real data area. Solution 1: use 'find' and 'cpio' and transfer all the data back. this would appear to require 2x current capacity of the filer to replicate all data out of snapshot. if you're using >50%, this method would fail. Solution 2: use 'find' and 'diff' and 'cpio' to enhance solution 1 with a check. Now only files which differ from the snapshot will be replaced. Solution 3: dump the snapshot to tape, and then restore from tape after removing existing snapshots. Solution 4: boot from floppy, use prev_cp and wack? Has anyone had any experience with 'prev_cp' and 'wack'? We're leaning at #4. Any comments would greatly be appreciated! ######################################## # Christoph Doerbeck # Motorola ISG # email: doerbeck(a)dma.isg.mot.com

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Re: backup times
by sirbruce＠ix.netcom.com 22 Apr '98

22 Apr '98

On 04/22/98 11:15:20 you wrote: >Because if you have 8 filers, most, potentially all with > 20GB of >compressed data, putting an autochanger on each filer is prohibitively >expensive. Going the other route and putting, say, a DLT7000 on each >filer is also nuts. Cost for one of those around here (toronto, >ontario, canada) is something like $12500 plus the cost of a tape >monkey to run around and change tapes daily. While I agree that ultimately network backup is a cheaper and easier to manage alternative solution, I think you overstate the case against local backup. There are several key points that you need to be aware of in a network backup solution: 1. If you have a good (read - frequent) backup scheme, and your filers are large, you won't save on the number of DLTs you buy. Consider the case where those 8 filers all have to be backed up once/day, and it takes about a day to run the backup. You'll have to have just as many DLTs streaming away on that backup host as you would if each one was attached to it's own filer. Now, a more realistic example would probably allow you to cut the number of DLTs in half, but you will have to make sure your schedule everything properly. And can recover quickly if you have a failure. 2. You probably can't afford to saturate whatever network you already have, so you'll need a dedicated backup network. So gigabit is overkill, but once you factor in your 100mbit hubs, the possible need to buy additional network interfaces on your filer and the backup hosts to support this, not to mention the backup host itself, the cost differential is less than it first appeared. 3. You SHOULD have a tape monkey running around to change tapes daily. You don't want those tapes sitting there; you want them labeled and catalogged and shipped off-site. This doesn't change if you have a central backup solution, and at the very least you'll still have to change tapes just as often. Unless you get a library with a bigger tape capacity for your central server than you would for an individial stacker for each filer, which again is a price consideration. 4. You will incur a performance penalty, although with the more recent releases that penalty may be less than 10%. So, IMHO, network backup is probably more expensive at 4 filers, cheaper but not worth the hassle at 6, and only becomes really preferable at, say, 8 filers. But these numbers all depend on how big your filers are and how frequently you want to do your backups. Bruce

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backup and Restore questions
by Menachem Kaiser 22 Apr '98

22 Apr '98

Hi, We are currently evaluating a network appliance solution for our site. We still have deep concerns about our abilities to backup such vast quantities of data from one source and even greater concerns on our ability to restore such vast quantities of data in the event of a disaster within a feasable time frame. I would like to hear from people about how they backup their systems - i.e.: What backup software do you use? What size is your file server and what size are the partitions? Is the tape directly connected to the file server or do you backup via the network? If you backup via the network, how is your file server interfaced to the network (dedicated backup network(s)? - 10/100 Mb/s?) Do you use ndmp? How many streams of backup do you use in parallel? What speed/rate do you backup (GB/Hr) per drive? Do you utilize more than one tape drive for backups? Have you needed to restore a file system? If so, how long did it take you (GB/Hr) ? Were you able to retore in parallel streams? Since the list of questions came out long, I will be more than happy to call you and poll you verbally on the above (send me your number). I will even be more than happy to post the statistical results of those willing to participate.

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Re: backup and Restore questions
by Mark D Simmons 22 Apr '98

22 Apr '98

> Hi, > > We are currently evaluating a network appliance solution > for our site. > > We still have deep concerns about our abilities to backup > such vast quantities of data from one source and even greater > concerns on our ability to restore such vast quantities > of data in the event of a disaster within a feasable time frame. > > I would like to hear from people about how they > backup their systems - i.e.: > > What backup software do you use? A cron job on an admin host kicks off a full-filer dump on each of our erm 9-going-on-10 filers using rsh and loggid the output to backups-logs. > > What size is your file server and what size are the partitions? Ranging from piddly 50GB ones to reasonably meaty 200MB. > > Is the tape directly connected to the file server > or do you backup via the network? We have 4 Exabyte stackers, 3 DLT4700's and a single DLT4000 all directly attached to filers. When there's a tape drive problem (infrequent but hey they involve lots of moving parts) we get a little downtime during lunch or beginning/end of business and perform a quick halt-detach-reboot cycle, work on the drive while providing service, then do a halt-attach-reboot to bring it back together. Sometimes this stalls a lot of machines and it'd be ideal if we didn't have to do it but pretty much everything recovers, though we have to get brutal with locks the filer wishes to honour after reboot when in actual fact the client has just gone awol and won't talk to the filer about the lock... > > If you backup via the network, how is your file server > interfaced to the network (dedicated backup network(s)? - 10/100 Mb/s?) We've considered the option but we'd need a dedicated LAN to get the performance and avoid loading the production network on the basis that we do serve sites around the world. > > Do you use ndmp? Still waiting for it to mature and appear in products we feel happy to use and rely upon. > > How many streams of backup do you use in parallel? One per filer, cos we've only *currently* got one device on each filer. > > What speed/rate do you backup (GB/Hr) per drive? About 2.3MB/sec. (I reduced the numbers to that dimension and can't recall what they were in GB/hr - I'm sure you can work them out). > > Do you utilize more than one tape drive for backups? One drive per box though we're looking at two or more per box in future. > > Have you needed to restore a file system? Sadly yes, way back a year or so ago on an older box on an older release of the software we suffered a catastrophic loss of a box. It took me a long time to restore the bits we needed because I was, at the time, reduced to using ufs_restore from a Sun over the network. Still managed 1MB/sec though. Otherwise I just smugly cp things out of snapshots. > > If so, how long did it take you (GB/Hr) ? Days. > > Were you able to retore in parallel streams? Nope. > > > Since the list of questions came out long, > I will be more than happy to call you > and poll you verbally on the above (send me your number). > I will even be more than happy to post the > statistical results of those willing to participate. I hope people chip in - it'll be interesting to see if backups on filers has become customer-target no 1, now that there're so many good things in DOT5 to play with.

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Re: Restoring A LOT from snapshot
by sirbruce＠ix.netcom.com 22 Apr '98

22 Apr '98

On 04/22/98 10:00:56 you wrote: > Solution 4: boot from floppy, use prev_cp and wack? > Has anyone had any experience with 'prev_cp' and 'wack'? > >We're leaning at #4. Any comments would greatly be appreciated! If support says #4 will work, and they'll "support" it, then I would choose that method myself. Bruce

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Re: backup times
by Mark D Simmons 22 Apr '98

22 Apr '98

> > On Mon, 20 Apr 1998, Stephen Manley wrote: > > > > > Depends. What version of ONTAP are you running right now that you see > > > this behavior? > > > > sorry, good question. 4.3.1D5, and possibly also with 4.3.3. > > > > The basic data I know, Data ONTAP 5.0 runs significantly faster (50%?) than 4.3. > Furthermore, it should not crank at 100% CPU for minutes/hours at a time. > We've gotten to the point here that people don't really notice an effect > when we run dumps, anymore. > > Also, if I could ask a survey question of people (if this is not an acceptable > forum for this, just flame me ;) How do people out there use dump? > > 1) rsh to local drive. Currently our only backup possibility, it's working fairly well for now but as I've mentioned previsouly we're looking to seriously load our filers (before getting some more 8) and the backup times are looking daft! Specially as we do full backups every night, and will continue to do so until such time as we have a sterling installation of something like Veritas such that incrementals become manageable and reliable. > 2) rsh to remote drive. Why? streaming across the main network is a bad idea (tm) and CIFS put paid to the utility of the technique anyhow. > 3) NDMP to local drive. This is what I want to move toward, using tape-drives attached to the filer (ie where the data lives) and control across the network to a Veritas/other control box, where the indexes get kept. > 4) NDMP to remote drive. Doh! Only when we've got our dedicated Gigabit Ethernet backup network in place, which current estimates place around the next ice-age. > 5) I don't. > > Inquiring engineering minds are curious to know. :) Forgive my sarcasm in the above - you wouldn't believe the angst the word 'backup' causes around here at times. Plus I think I got out the cynical side of my bed this morning. > > Sm

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Re: backup and Restore questions
by sirbruce＠ix.netcom.com 22 Apr '98

22 Apr '98

Just some comments from my own experiences with backup at Network Appliance: On 04/22/98 08:57:07 you wrote: >| Do you use ndmp? > >No. Although things have gotten better, directly attaching any device >with a robotic arm to a filer is not going to end in a pleasant way. >If the stacker hangs (as some do), you need to power-cycle the filer and >the stacker. This means downtime. I would rather reboot a dedicated >unix box that does backups (and will not interfere with anything). I can say that having used several DLT-4700 stackers attached to several filers over the years, I NEVER had one of those stackers hang. So I would have to say that this is pretty rare for the DLT-4700. If you use another stacker, I suppose it could be more of a problem. I did have some DLT-4000s fail, but nothing like an intermittent hang to be cleared via power-cycle; they busted completely, requiring them to be returned. It IS true that if your dump device goes out to lunch during a dump, and you started that dump via, say, rsh, you will have to reboot the filer to kill that dump session (otherwise you could ctrl-C). There was some talk of a dump abort command being done, and/or the notion that one might be able to use ndmp to kill that old session, but I don't know if either are possible with the latest software. However, rebooting was sufficient (no power cycle needed for the filer) to clear the session, and that usually takes less than 5 minutes, so downtime wasn't much of an issue either in those cases. For us, it was cheaper to have that directly attached device than to spend money on increased network infrastructure for network like dedicated gigabit, the dedicated UNIX server, the software, etc. For someone with different requirements, network backup might be the better way to go; it certainly scales better in the long run if you can set it up properly to start with. >| How many streams of backup do you use in parallel? > >I can only do 1 (only 1 drive). My friend does 4... >He also does something called vaulting. After a level0 >is done, the software then duplicates the tapes and spits them out. >Thus he sends the copies off site and can restore more effectively >in case of an emergency (no delay in getting tapes back). This software duplication sounds very cool... actually, something that did it in hardware would be even cooler. Allowing you to keep on copy on-site is a very nice idea. I'll have to try that in my next backup plan. >| What speed/rate do you backup (GB/Hr) per drive? > >Slow. 3-4GB/hr. My goal is to increase than an order of magnitude. >I would like to be able to restore 50GB in less than 1 hour. >AIT looks like the quickest (and least expensive) way of accomplishing >this. A word of caution here... I doubt changing your tape drive is going to increase your backup or restore times if you continue to do it via rsh dump/restore over the network, given the limitations of the software. Things may have improved with the more recent release, but my advice would be to either use local tape or use NDMP over the network if you want to get better performance. amd stick with DLT. To the original poster - Network Appliance can provide you with numbers for all of these things, and I can tell you that last year the numbers they were using were pretty authentic, having been put together from customers, in-house testing, and "real world" in-house testing (myself running the backups as an internal customer). I wouldn't have any reason to doubt the numbers they might give out today. Bruce

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backup times
by Tom Yates 21 Apr '98

21 Apr '98

people are familiar with the temporary performance hole in one's toaster when starting a backup via "rsh toaster dump 0fqwerty etc. etc.", right? am i imagining it, or is it getting worse with later versions of ONTAP? it's got to the point where users are substantially hampered in working over the weekend when the backups kick off becasue CPU goes to 100% used and stays there for tens of minutes (and, for that matter, at various times during the backups). am i doing something wrong? Tom Yates - Unix Chap - The Mathworks, Inc. - +1 (508) 647 7561 MAG#65061 DoD#0135 AMA#461546 1024/CFDFDE39 0C E7 46 60 BB 96 87 05 04 BD FB F8 BB 20 C1 8C

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