Pause/Resume prefetch

[npelov]

Hi,

My SSD died and I've put an old 160 GB HDD for main OS temporarily while I wait for warranty service. The old hdd is terribly slow, especially when seeking. I'm using smaller SSD for L2 cache. I have this problem that prefetch takes forever if L2 cache is not present. I waited 10-20 minutes after login for 8 MB prefetch (8 MB, not GB). And yes, the prefetch was "delayed" type - does not start on windows boot. Once L2 is filled system boots fine. But the old ssd I have sometimes vanishes and L2 is reset. I have to power cycle the PC to get it back on, but L2 has to be filled again and the 30 minutes total boot time is awful.
Maybe there should be pause/resume prefetch function. Or if there is a way to block OS reading while prefetching to avoid seek overhead... On a system without fast L2 prefetch is not an option in the current state.

[minhgi]

You need to check your wiring for loose connection and update your AhCI driver. SSD should not loss cache a while in the middle of usage.

[npelov]

The SSD is not loosing cache. The SSD itself is disappearing, which is hard disk problem not primocache. The problem I have is with prefetch kicking in the wrong moment, while OS still haven't finished loading. If you have a lot of ram and slow hard disk the OS loading time is bigger and it overlaps with primocache prefetch and it gets really slow. Even if you have flash drive/ssd cache it still can happen after windows update. So pause/resume for prefetch would be nice.

I tried to uncheck the prefetch function and that sped up the OS load, but do I loose prefetch data when I do that?

[Support]

I think you may just uncheck the Prefetch function in PrimoCache. It is only for L1 cache, not L2.

[npelov]

I fixed the problem. The partition was copied 1:1 from an SSD. It has been on the SSD for ages, so it got very fragmented. When I copied it to a HDD booting got so slow that it was past the delay of prefetching. Defragmenting fixed it. Now booting stops before prefetch starts.

[Jaga]

That may be a good way to realign (and read-ahead tune) a SSD for long-term use without hammering it with writes. Make a copy to a spindle drive, fully defragment, image back over the original drive. Just one write per cell for the image task.