QRecall Community Forum
  [Search] Search   [Recent Topics] Recent Topics   [Hottest Topics] Hottest Topics   [Top Downloads] Top Downloads   [Groups] Back to home page 
[Register] Register /  [Login] Login 

Simultaneous backups/copies RSS feed
Forum Index » General
Author Message
Mark B Anstendig


Joined: Jun 13, 2010
Messages: 4
Offline
Can QRecall simultaneously backup more than one script at a time, like Retrospect 8 can?

If so, can it simultaneously backup scripts that are on separate partitions of the same hard drive, which Retrospect cannot?

Can QRecall also simultaneously backup separate hard drives that are mounted in the same hard drive enclosure, like my Firmtek/Seritek 5 Bay drive enclosure. My Retrospect 8 will not simultaneously do the 5 separate drives mounted in my 5 Bay Firmtek/Seritek drive enclosure, but waits while each is copied separately, one after the other. That enclosure is connected to my Mac Pro computer by one single SATA cable. The five drives are 2 TB drives, formatted in Disk Utility as Mac OS Extended journaled.

My Computer info is:

Model Name: Mac Pro
Model Identifier: MacPro1,1
Processor Name: Dual-Core Intel Xeon
Processor Speed: 3 GHz
Number Of Processors: 2
Total Number Of Cores: 4
L2 Cache (per processor): 4 MB
Memory: 8 GB
Bus Speed: 1.33 GHz
Boot ROM Version: MP11.005C.B08
SMC Version (system): 1.7f10
Hardware UUID: 00000000-0000-1000-8000-0017F20265EE

Thanks for the answers to these questions.

Mark B Anstendig
James Bucanek


Joined: Feb 14, 2007
Messages: 1568
Offline
QRecall can perform any number of actions simultaneously, with some logical and practical limits:

The logical limit is that a QRecall archive can only be modified by one action at a time. For example, if you schedule multiple actions to act on the same archive, they will be performed one at a time.

QRecall can capture the same source item to more than one archive simultaneously.

By extension, it can capture multiple source items to multiple archives simultaneously.

Normally, QRecall (at least the current Beta) will try to avoid doing this because it often isn't very efficient. There's a hard disk phenomenon known as "thrashing" that can significantly reduce the efficiency of data I/O. A single process reading or writing to single physical drive is usually extremely efficient, reading or writing data at pretty close to the drive's maximum performance. However, if you start two processes reading or writing data to a single physical drive, the two compete with each other. They cause the drive to constantly jump back and forth between the two files—the drive spends more time seeking than it does reading/writing data. For example, verifying two archives on a volume might take an hour (30 mins each) if done sequentially. Try to verify them simultaneously, and it could 3 or 4 hours, to say nothing about the wear and tear on the drive. Reading/write to two volumes (partitions) of the same physical drive or RAID set is particularly bad.

Another factor is memory and CPU resource. QRecall uses a lot of memory and is highly optimized to use multiple CPU cores. Unless you have tons of RAM and lots of CPU cores, QRecall will quickly saturate your system. Too many heavy processes causes memory "thrashing", which can also degrade the performance of your system.

So to efficiently perform multiple actions simultaneously, you should (a) have lots of RAM and CPU cores, (b) be reading from volumes that are on physically separate hard drives, and (c) be writing to archives that are on physically separate hard drives.

The current beta release of QRecall has a number of settings to help you avoid thrashing and to run QRecall actions one at a time, because it's generally more efficient. These settings can be found in the Scheduler tab of the QRecall preferences. See the beta release notes for a complete description. Turn these limits down or off as you see fit.

- QRecall Development -
[Email]
James Bucanek


Joined: Feb 14, 2007
Messages: 1568
Offline
James Bucanek wrote:So to efficiently perform multiple actions simultaneously, you should (a) have lots of RAM and CPU cores, ...

To comment on my own post ...

You have 8GB of RAM and 2 CPUs with hyperthreading. This puts your system in the midrange of performance.

You can probably run two QRecall actions simultaneously with good to excellent performance, as long as those actions aren't thrashing a single drive.

- QRecall Development -
[Email]
Mark B Anstendig


Joined: Jun 13, 2010
Messages: 4
Offline
Retrospect (Ret) will run up to 8 scripts simultaneously if they do not have source or target on the same drive as another script. If two scripts have sources or targets on the same drive, then the last one will have to wait until the first one finishes. That is fine with me.

What Ret seems to not be able to do is run simultaneous scripts to the 5 separate drives installed on my Firmtek Seritek 5 Bay drive enclosure simultaneously. At the moment Ret is only running the otherwise unrelated scripts targeted for those 5 drives one drive at a time. (BTW, there is only one script per drive).

So my concern and interest in QRecall is to find a backup application that can address separate backup or copy scripts to each of those 5 hard drives installed in the SERITEK enclosure and run their backup scripts simultaneously, not one at a time.

Do you or anyone else know the Firmtek enclosures and know it QRecall can back up separate, unrelated scripts to each one simultaneously?

As soon as the next MacPro machines come out, I will be buying one. So capability should not be a big issue.

I would be very grateful for the answer to this question.

Thanks,

Mark B Anstendig
James Bucanek


Joined: Feb 14, 2007
Messages: 1568
Offline
QRecall's principle restriction is that it will only allow one action to update an archive at a time. Beyond that, you can create as many archives as you want and run as many simultaneous actions as you want.

What I was basically saying in my earlier post is that QRecall will let you start as many actions as you like—you could perversely schedule a hundred actions to run at once—it's just unlikely to be very efficient.

I encourage you to experiment and report your results. Schedule five actions to run at the same time and set the scheduler to allow unlimited number of concurrent actions. Then drop it down to 4, 3, 2, and 1 and see what gives you the best performance.

- QRecall Development -
[Email]
Mark B Anstendig


Joined: Jun 13, 2010
Messages: 4
Offline
Thanks,

I assume archive is different from a simple copy of a drive or a backup of a drive.

I am not interested in archiving. I just want to create a schedule to do around 5 separate copies of 5 hard drives containing my historic photograpgs (see www.anstendig.com) and to do them simultaneously. The copies will be, of course, on another 5 drives.

Also, does QRecall work with FIS based port
multiplier enclosures. FIRMTEK contacted me and thinks Retrospect cannot do simultaneous actions on their enclosures because Ret. has a problem working with that type of FIS based enclosures.

Thanks again,

M
James Bucanek


Joined: Feb 14, 2007
Messages: 1568
Offline
Mark B Anstendig wrote:I am not interested in archiving. I just want to create a schedule to do around 5 separate copies of 5 hard drives containing my historic photograpgs (see www.anstendig.com) and to do them simultaneously. The copies will be, of course, on another 5 drives.

QRecall does not copy drives. It's an advanced backup and document archiving system that analyses the data in a large collection of files and incrementally captures only unique data that has changed in a compact archive.

If you just want to copy five drives worth of data, everything you need is in the OS. iCal and few AppleScripts is all you need.

Personally, I think you're wasting a lot of CPU time and bandwidth with that approach, and you're gaining very little in the way of data integrity. A RAID would offer better security (and possibly better performance). QRecall would be a vastly more intelligent, efficient, and secure method of preserving your data.

Also, does QRecall work with FIS based port
multiplier enclosures. FIRMTEK contacted me and thinks Retrospect cannot do simultaneous actions on their enclosures because Ret. has a problem working with that type of FIS based enclosures.


QRecall will work with any volume you can mount in OS X.

- QRecall Development -
[Email]
Mark B Anstendig


Joined: Jun 13, 2010
Messages: 4
Offline
Thanks for your views. I respect them.

I reached Retrospect this morning and they found the problem. It was an easy fix.

Everything is running super again.

But I will suggest QRecall to my colleagues in my Mac User groups.

Thanks again....very much,

Mark B Anstendig
915 Fulton Street
San Francisco, CA 94117
415-775-3575
mba@anstendig.com
www.anstendig.org
www.anstendig.com
www.hamburgastrology.com
www.pathofliberation.com
 
Forum Index » General
Go to:   
Mobile view
Powered by JForum 2.8.2 © 2022 JForum Team • Maintained by Andowson Chang and Ulf Dittmer