Why is avast! the only AV that I know which totally ruins SSD caching systems? I’ve used eBoostr in the past to cache hot data from HDD to SSD for significant speedup. And whenever I ran full system scan, avast! wrecked the eBoostr cache, filling it with cold data (stuff I haven’t executed or viewed for months), negating all SSD caching speedups because it’s the data I don’t need regularly. Same happens now with PrimoCache. And now I remembered it was also happening with Sandisk ExpressCache, but back then I couldn’t figure out why. Considering avast! wrecks software caches, I’m suspecting it’s doing the same to SSHD drives that have SSD integrated on circuitry. It’s all algorithm based so if avast! is accessing data in such a weird way that it confuses all caching apps, it’ll likely do the same to SSHD’s.
My main question here is, why is avast! the ONLY AV that does this? Windows Defender doesn’t, neither does Comodo (CIS). I don’t remember AVIRA, Panda Free and AVG doing this either.
I’ll ask someone to try to reproduce the behavior.
As for the full system scan… well, I don’t think Avast accesses files in any special way - it simply enumerates all the files on the local drives and reads them / scans them. The order of the files might differ according to the option “Scan files in order they are stored on disk” - but whatever the order is, if the cache is intercepting our reads, then I guess it would be flushed (unless we act as a cache ourselves and scan only recently accessed files - but then it wouldn’t be much of a full system scan). So I’m wondering what could be the difference… (but I’m not familiar with those caching tools, so I’m just wondering at the moment).
Must be the way how avast! parses the files that trips the caching software that no other AV does in such a way.
The thing is, when it’s on-access, you access files you need anyway, meaning they’ll be relevant anyway. But if you do on-demand scan, it parses files from start to end and that’s what wrecks the caching algorithms.
[ol]- Get away from an old 80 GB (6+ year) platter drive
Use the SSD drive as a consumer would; i.e., home environment with as few disk writes as possible[/ol]
Installed January 1, 2015 with 2.49 TB written to disk since install. Max TB rating is 75 TB.
Not seeing unusual disk write activity and system is used everyday.
So the point of caching is to minimize disk writes and speed up system performance but avast is somehow removing all cached SSD data on an on-demand scan, correct?
Not “removing” as is. It just fills entire cache with cold data that’s not helping to accelerate anything. I’ve noticed this the instant I’ve rebooted my system after full system scan with avast! and it took ages to boot with horrendous HDD grinding. Usual cached boots are super swift with zero HDD noise. I just see blinking HDD LED on case front, but no noise from HDD.
No, you’re missing the point here. It doesn’t wreck systems that use SSD as the only storage drive (or as a boot drive).
It’s causing huge problems to systems where HDD is still the primary storage, but is aided by the SSD cache to accelerate reads from HDD. It somehow interferes with the data caching algorithms and totally throws them off the track when doing full system scan. In theory, if you NEVER make an on-demand scan, everything will be fine.
I’m now going full SSD, but I’ve decided to post it here anyway because it is an issue. Plus, I don’t know if it affects SSHD hybrid drives that have caching algorithm and SSD embedded into the HDD itself.
Well, this all sounds like we’re doing something wrong… and while I may change my mind if we manage to reproduce the behavior, right now I don’t think it’s the case.
If you run an on-demand scan, scanning (= reading) all the files on all your hard drives, then I’m not surprised that a cache of a HDD-access caching software gets flushed; if it simply caches the last read files, I would expect it to be.
How it happens that it doesn’t behave like this with a different AV, I don’t know at the moment; I can speculate that the tool somehow detects that it’s an AV access and ignores it (= doesn’t cache). What this detection could be based on… well, it could be a known process name, could be an attempt to detect full disk enumeration (then the checkbox affecting the scan order could make a difference), could be something else (but I don’t think it could be the way the particular files are parsed; there’s no “standard” way of reading a file, and I definitely don’t believe everyone but us is reading the files in a “similar” way, just we are different).
We’ll see - I’ll keep you posted when we find out some more.
But why not a single OTHER antivirus does that? Caching software doesn’t just cache ALL data, it caches frequently accessed data. But in avast!'s case, even a single scan of a file seems to convince caching algorithms the file is a hot frequently accessed stuff and needs to be cached. Even though it’s really not.
I agree it’s weird… but that’s probably all I can say at the moment (not knowing what exactly the criteria for “frequently accessed data” might be).
A simple on-demand scan (context menu invoked, for example) opens every file just once (the subsequent reading of the data is kinda random, as there’s a lot of things going on - packer detection, scanning, possible signature verification etc.)
For full-system scan, it could be more (for some files) - due to the antirootkit scan and enumeration of autorun entries and running processes. If that could be the reason… we’ll see.
Usually single launch of the app or a game doesn’t cache the data on SSD. Unless the cache is already empty from start in which case it’ll try to fill it (first time fill). After that, caching algorithms decide what to keep and what to reject from the cache to utilize given capacity.
Launching apps and games 2 or 3 times, that however already creates significant boots in load times as well as responsiveness.
PrimoCache has a 60 days fully functional trial (no registration/account needed) if you want to poke it and see what’s going on. You’ll need any kind of SSD to use it for caching though.
in old days i had a sshd seagate with internal ssd 8gb , i remember few times after a scan with avast and follow a restart the sshd had the speed of hdd.
I dont know if it avast fault, but maybe connected with it, cache works like the cache of software solutions.