Slow Performance 7.6 Multi Server

[opj]

Hi Robin,

I've been using Multi Server 7.5/6 for 5 or more years. Six months ago I installed a new DLT S-4 drive on a dedicated scsi card in a Dell server, which previously had a SDLT 600 attached. Until a week ago, I was getting performance speeds of 1K or better. Now, with no apparent associated incident, I’m only getting 95MB; it starts off at 127 or so and within a minute or two it works its way down to 95-ish. This is true for both the local drive and its attached storage drives.

I’ve switch various devices and swapped out scsi cards and even reconfigured the attached storage device which it backs up, none of which has made a difference. At this point I can only assume it’s the software, which I did uninstall, removed folders and reinstall all without result.

I have several other servers, all running Windows 2003 R2 with SDLT 600 at Retrospect version 7.6.123 w/ hotfix 7.6.2.101.

Any suggestions from the Retrospect Backup Commando would be greatly appreciated.

 

[Ramon88]

These are always nasty things to resolve without having access to the system. But here are my 2 cts..

 

If you didn't change -anything- before the slowdown it also might be the drive or tape itself. Did you try a brand new tape? Did you use a cleaning tape on the drive?

 

Do you use anti virus software which might interfere (after an update) with Retrospect?

 

Can you swap the DLT drive from another server and see what happens?

[rhwalker]

It's possible that the system is thrashing, and doesn't have enough memory, and that something just pushed it over the edge where memory became tight.

[opj]

Thanks Ramon88 – your reply is worth way more than 2 cts.

Nothing was changed before the slowdown and I did switch out the tape drive to another 7.6 server and it worked flawlessly.

As for the AV, I’ll have to check on that as there was a recent version update. But, this AV version was applied to each of the other 7.6 servers each with a similar build to the troubled one.

Again, thanks for the response.

 

[Ramon88]

I'll make it 4ct then

 

Some AV software can (sometimes) slow down a backup. So it could be worth checking out.

 

Is it possible for you to create the same script from your troubled machine on one of your functioning machines and see how that performs? You could also create a smaller testing script and run it on both machines to compare.

 

And I have to agree with rhwalker that memory trashing might also be something to check.

 

Other things might be system related, like a malfunctioning network interface or defective network cable/switch or port.

 

Is it possible your DLT has termination trouble with that particular machine. It could be a SCSI controller problem.

 

If you have a bit of local storage you could try to create a Disk Backup and see if that is slow as well. That way you eliminate the DLT drive from the equation.

[opj]

Hi Rhwalker – Thanks for weighing in! After reading your note, I did several test backups while monitoring drive statistics and system use and nothing seemed abnormal – actually look pretty efficient.

This just may be an opportunity to rebuild the server, but I’ll entertain any other suggestions to avoid having to do so.

 

[opj]

Ok, I’ve stopped the AV service and did a tape (normal) test backup. The AV meddling thing was a great idea, but the same results.

OK, ok, ok, your “disk instead of tape†suggestion yielded results to the tune of 1750K! Alright, so now I’m looking into the scsi controller card. When I swapped scsi cards before, I swapped it with a spare - same model and type. Everything else, cable, terminator and various open pci slots in the server were tried, but not a completely different scsi card and driver.

It may just be, as you said, that combination of server, scsi card, and DLT drive that’s causing this problem.

Thanks, Ramon88, for putting me on the right track.

“forums are a great thingsâ€

ps. Let me know if there is some type of “kudos ranking†to which I can report you and rhwalker.

 

[Lennart_T]

It may be outdated firmware on the SCSI card.

[Ramon88]

Glad to be able to help. I'm not aware of any kudos ranking here and to be honest I don't think kudos harvesting would be a worthwhile pastime. It's nicer to know that one can help people out a bit and they appreciate it.

 

We've used various tape technologies with Retrospect since 1991 (I think). But we have switched to disks years ago because of the performance and non-linear aspects. Currently I'm beginning testing with a 16TB iSCSI appliance.

 

The only drawback is you don't have offline storage, which might be a wise thing. So we also pump data offsite through a fiber connection. Otherwise you can also let Retrospect duplicate data to removable/portable drives (even encrypt it).

 

As we need to back up a lot of data on a daily basis the speed of harddisks just makes a lot more sense. And it is cheaper than DLT or LTO.

 

But you need to make due with what you have. And if that's tape it needs to work.

 

One thing with tape is the need for 'streaming'. If the drive can't be fed data fast enough (maybe many small files - if you have developers working at you site, they generate large amounts of very small files) Retrospect might be struggling to keep the tape drive streaming. When that happens the tape drive needs to reposition a lot and that takes an insane (but understandable) amount of time. A harddisk just doesn't have that problem.

 

So maybe it's just the 'structure' of the data you are backing up that causes your problem.