Backup Software Skewes the cache

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ianmozzy
Posts: 10
Joined: Wed Nov 25, 2015 7:23 am

Backup Software Skewes the cache

Post by ianmozzy »

Hi
I use Macrium reflect to make a backup of my boot disk.
It is a 60 GB SSD

I cache it presently with 4GB of main memory.

I do a full backup once per month and differential backups daily. These are setup to be done automatically.

Each time the backup is done, all the taken SSD space is read, which will cause issues with the cache.

How do you instruct primocache to ignore this.

One method I can think of is pausing and restarting the cache automatically at specific times.

How is this done?

Thanks

InquiringMind
Posts: 365
Joined: Wed Oct 06, 2010 11:10 pm

Re: Backup Software Skewes the cache

Post by InquiringMind »

You could try using the Task Scheduler to call the appropriate commands to pause/restart PrimoCache at specific times. You could do a step further by creating a batch file to pause caching, take a differential backup and then restart it and use Task Scheduler to run that.

Another option - try Drive Snapshot for your backups. It doesn't affect the contents of PrimoCache (at least, it's never done so on my system) and, while commercial software, the download does offer a month's free backup and unlimited restore capability (so you could just download a new copy each month). It is also small enough (400KB) to fit on a floppy if you still use one, and very reliable (even able to copy data from failed hard drives).

BonzaiDuck
Posts: 76
Joined: Wed Jan 11, 2017 12:57 am

Re: Backup Software Skewes the cache

Post by BonzaiDuck »

I also use Macrium Reflect v.7. If there were ever any problems with using it, they likely derived from using L1+L2 caching strategy on a spinner, with SSD cache and a RAM cache. If it is indeed an issue using Macrium, eliminating the L1 cache in that caching strategy solved the problem.

I'm thinking that I could be the clueless person in this exchange, or -- alternatively -- that ianmozzy has some issue that derives from something else still related to the configuration, and that he has inferred that Macrium is reading through the cache. InquiringMind might accept this inference and makes his recommendations and suggestions.

But I never had a problem caching my boot-disk directly to RAM (L1) and using Macrium Reflect to backup my system. Instead, I'm pretty sure I MAY have had a problem using Macrium with an L1+L2-cache strategy on a secondary spinner drive, and eliminating the L1 part of it resolved things.

IanMozzy -- did you ever run it past Macrium tech-support to get their take on things? If you're using the Macrium Free version, I bought the license and I can probably use my tech-support subscription to run it past them. I hadn't thought to do so before.

So to summarize, Until about March this year, I had boot-drive cached to L1 and a spinner cached to L1 plus an SSD L2. Macrium would run regularly with daily backups until some point -- maybe a week or two -- when it would fail making the backup and I'd have to run CHKDSK repair on the source spinner disk. When I stopped caching the spinner to L1, continuing to cache it to L2, these difficulties disappeared.

But -- there was never a problem with the C: boot volume cached exclusively to L1 RAM.

tyraelmetanamede
Posts: 22
Joined: Tue Feb 05, 2019 11:17 pm

Re: Backup Software Skewes the cache

Post by tyraelmetanamede »

if you want to automatically pause and resume PrimoCache (so the L1/L2 Cache won't get tainted) you can use a small tool i wrote:

https://www.romexsoftware.com/bbs2/en-u ... 38&p=13264

rutra80
Posts: 55
Joined: Fri Aug 14, 2015 9:10 am

Re: Backup Software Skewes the cache

Post by rutra80 »

Or instead of pausing, change strategy to Write Only.

tyraelmetanamede
Posts: 22
Joined: Tue Feb 05, 2019 11:17 pm

Re: Backup Software Skewes the cache

Post by tyraelmetanamede »

wouldn't that destrooy the current read-cache - which in return would require the SSD to rebuild (many writes!) the read cache?

rutra80
Posts: 55
Joined: Fri Aug 14, 2015 9:10 am

Re: Backup Software Skewes the cache

Post by rutra80 »

no, Write Only strategy caches only writes.

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