Thoughts on using SRT caching

[voodoodrul]

On one of my machines, I have an odd mash-up:

240gb Kingston Hyper-X Predator HHML M.2 add-in card
1tb Samsung 850 EVO
2 x 2tb WD Black RAID0
1 x 5tb Toshiba PH3500u

It's kind of a mess. Now because I like to live dangerously, I was considering enabling the Intel SRT caching so a 64gb slice of the EVO would cache the 2x2tb set and store "disposable" stuff like Steam games there. With caching enabled, it seems to have great perf in benchmarks, since it's really just exercising the SSD during that time.

But I have a few reservations for using SRT:

1) The RAID0 is already risky enough. Adding the cache to it adds yet another chance for data loss
2) The SRT caching will be writing to the SSD quite a bit. Since by definition there isn't enough room in the cache to hold everything being read, that means just reading some data from disk will involve writes. Probably not a big deal, but it could be useless wear.


What do you guys think about SRT being used to boost perf on large data (non-OS) drives?

 

[Cerb]

1) If SRT is in enhanced mode (default), you can rip the SSD out with the PC on and not lose any data. Only in the other one, maximal, I think, will the cache risk that. In the default mode, writes go to the SSD and HDD at about the same time, and the SSD is used only as a read cache.

2) Maybe, but the 850 Evo's 3D TLC has about the endurance of typical 2D MLC, so no worries.

You are adding complication with the RAID 0, so as with anything like that, have backups for your important files, and you should be OK.

 

[Dasa2]

out of curiosity how does the 5tb toshiba perform vs the raid0 wd black

from what i can tell the caching software chooses rather small chunks of data and shares the load with the hdd which perform fairly well with large sequential files so the wear and tear to the ssd is probably nowhere near as bad as you fear
my 128g ocz synapse has been working fine for ~4 years now acting as a 64g cache for up to 3tb hdd with both the os and ~1tb of games installed at any one time
its smart data still shows it in good health

 

[voodoodrul]

out of curiosity how does the 5tb toshiba perform vs the raid0 wd black

The 5tb Toshiba holds its own, sitting somewhere in the middle between a single WD2002FAEX and 2x RAID0, according to ATTO. It's a good drive and probably performs on par with the WD Black 4tb models, maybe a little better. It's not a quiet drive and appears to have no acoustic management, but it's not "loud" either. If I had to choose between a WD Black 4tb and the Toshiba, I'd go with the Toshiba, regardless of price. When price is factored in, it's a no-brainer to choose the Toshiba.

Thanks for the responses on the SRT caching behavior. I will keep running it. I've decided to rip out the M.2 drive - because it was causing UEFI boot issues and kicked my system down into legacy boot, increasing POST and boot times significantly. And I've moved the Toshiba drive off to my server for backups - really fast backups. Ha.

I don't keep anything on the desktop that is worth backing up; that's what the NAS and obsessive backup scheme is for.

One other question - is over-provisioning really worth doing? Right now on the SSD I have a 64gb unallocated chunk, a 64gb SRT cache, and the rest for the OS and apps. I suppose the 64gb unallocated makes sense, but maybe it should be larger.

 

[ShintaiDK]

I dont see the point in SRT. SRT was essentially the cheap mans SSD in the early days. Today that tech is pretty much dead. You would have to more or less access the same patterns on your HDs to make it worth while.

 

[Cerb]

I dont see the point in SRT. SRT was essentially the cheap mans SSD in the early days. Today that tech is pretty much dead. You would have to more or less access the same patterns on your HDs to make it worth while.

More specifically, you will have to blow out your RAM cache, but still have your last 64GB worth of data used be what you need to load into RAM, all the time. IIRC, SRT is just a LRU cache.

 

[voodoodrul]

More specifically, you will have to blow out your RAM cache, but still have your last 64GB worth of data used be what you need to load into RAM, all the time. IIRC, SRT is just a LRU cache.

This serves a useful purpose for me - essentially keeping the last couple of games played in cache. After a power cycle, the first load times for those games will be improved to SSD-like, negating much, if any, value of actually storing games directly on the SSD. I can store a couple of TB's of games on the HDD and not have to manually copy games I'm interested in playing at that moment back to the SSD. The worst penalty is choosing a new game to play, in which case the cache is primed with that data without having to do anything as a user. That's the theory anyway.

 

[ShintaiDK]

You got a 240GB+1TB SSD. Isnt it just a matter of cleaning up games you dont play anymore?

 

[voodoodrul]

You got a 240GB+1TB SSD. Isnt it just a matter of cleaning up games you dont play anymore?

True enough, but imagine that instead of getting rid of old games, they just automatically paged out to slow HDDs, then when needed, they are automatically paged into fast SSD storage.

The alternative approach is to manually manage aging data. It gets old, you delete it. Eventually you get interested in the data you deleted and now you have to restore it, download it again, copy files, whatever. In a controlled use case, SRT does this for you, more or less.

 

[BonzaiDuck]

ShintaiDK has always been a skeptic about ISRT, as have many whose names I could recall if I pondered it.

The first question to ask: Are the software drivers stable? Does the caching system occasionally become a crashing system? I've had enough experience with it to say "No, it does not." Any problems of instability are most likely due to something else, unless the SSD itself is not reliable.

The second question: Does it seem to make an improvement? (a) the answer is "yes" for benchmark tests, and (b) it depends for usage patterns. It's neither necessary nor much useful to cache BD rips, MPG or other HD video formats for playback. But either some caching programs or all of them get that straight without user intervention. Some sorts of activities don't benefit much from caching, if at all.

But I think the OP is a data point in my information on this practice, and I am another. I think many games load a lot of material into memory at the same time, and so a faster non-volatile source benefits performance in noticeable ways. I do it myself.

If you ask me whether you should use ISRT as opposed to something else, I'll say you're limited to the controller chip's way of doing it and to caching in RAID mode for all disks. This by itself is not a problem, since you can run a single disk in BIOS RAID mode. You could have a single disk to boot from, and in addition a RAID array of two or more other disks. Since you need RAID to implement ISRT in a peculiar "RAID" volume encapsulating the SSD cache drive and the accelerated HDD (when I did it with my Z68 chipset), you are totally stuck with RAID mode. This may not be a drawback for you, but there had been troubles implementing TRIM for normal RAID volumes of SSDs. It was only resolved subsequent to issue of the Z77 chipsets, and may have been BIOS-version dependent. Resolution seems to arise from simply updating a BIOS and/or installing a newer IRST version.

There are alternatives: for certain PCI-E SATA controllers with a particular group of Marvell controller chips, there is a feature called Hyper-Duo, which had looser requirements and allowed for use of SSD cache-drives larger than 64GB. It still required configuration within the controller-card's BIOS.

Finally, there is the Chinese company Romex and its software Primo-Cache. This is also a rock-stable software I've tested on a laptop and two desktops, and hasn't missed a lick since the beginning more than a year ago.

You can cache either RAID-mode drives or AHCI drives, or combinations of both on different controllers. You can use any size SSD to cache a large HDD, any various RAID arrays of HDDs, or combination of individual drive volumes configured by something like StableBit into a drive-pool.

The HDD caching to SSD is only a secondary feature, since the software has an "L1" which caches an SSD or RAID-SSD, HDD or RAID-HDD -- to RAM. You can cache an "L2" configuration of paired SSD/HDD to RAM.

Primo works to providing L1 and L2 caching for non-Samsung drives, in harmony with RAPID caching for the 840 and 850 drive. Or, you can simply disable RAPID for the Sammy and use Primo instead.

If you have a 16GB kit or kits installed, and you have certain usage patterns which don't take advantage of it, you can get some extra value this way with Primo's L1 caching.

It has been argued that spending money on a 60GB drive is more wasteful than buying a larger drive, and that it's better to use even a 60GB unit for an NTFS storage volume place for storage, or even part of a RAID. But some very large HDDs can cost $200 or more (last I looked!) and so even a modestly-sized SSD would have benefit and not add much more than $40 to the equation.

It may have been the poor man's SSD, but it is no less useful for better enabling large HDD capacity when anything over 1TB as an SSD would be hard to find unless it were Intel's recent NVMe card of 1.2GB at something as high as $700.

You don't add anything to power-consumption of any consequence. If the system is stable, the caching should be reliable, or so I have found. And caching has been done in hardware configurations from much earlier days in computing history.

 

[voodoodrul]

ShintaiDK has always been a skeptic about ISRT, as have many whose names I could recall if I pondered it.

The first question to ask: Are the software drivers stable? Does the caching system occasionally become a crashing system? I've had enough experience with it to say "No, it does not." Any problems of instability are most likely due to something else, unless the SSD itself is not reliable.

The second question: Does it seem to make an improvement? (a) the answer is "yes" for benchmark tests, and (b) it depends for usage patterns. It's neither necessary nor much useful to cache BD rips, MPG or other HD video formats for playback. But either some caching programs or all of them get that straight without user intervention. Some sorts of activities don't benefit much from caching, if at all.

But I think the OP is a data point in my information on this practice, and I am another. I think many games load a lot of material into memory at the same time, and so a faster non-volatile source benefits performance in noticeable ways. I do it myself.

If you ask me whether you should use ISRT as opposed to something else, I'll say you're limited to the controller chip's way of doing it and to caching in RAID mode for all disks. This by itself is not a problem, since you can run a single disk in BIOS RAID mode. You could have a single disk to boot from, and in addition a RAID array of two or more other disks. Since you need RAID to implement ISRT in a peculiar "RAID" volume encapsulating the SSD cache drive and the accelerated HDD (when I did it with my Z68 chipset), you are totally stuck with RAID mode. This may not be a drawback for you, but there had been troubles implementing TRIM for normal RAID volumes of SSDs. It was only resolved subsequent to issue of the Z77 chipsets, and may have been BIOS-version dependent. Resolution seems to arise from simply updating a BIOS and/or installing a newer IRST version.

There are alternatives: for certain PCI-E SATA controllers with a particular group of Marvell controller chips, there is a feature called Hyper-Duo, which had looser requirements and allowed for use of SSD cache-drives larger than 64GB. It still required configuration within the controller-card's BIOS.

Finally, there is the Chinese company Romex and its software Primo-Cache. This is also a rock-stable software I've tested on a laptop and two desktops, and hasn't missed a lick since the beginning more than a year ago.

You can cache either RAID-mode drives or AHCI drives, or combinations of both on different controllers. You can use any size SSD to cache a large HDD, any various RAID arrays of HDDs, or combination of individual drive volumes configured by something like StableBit into a drive-pool.

The HDD caching to SSD is only a secondary feature, since the software has an "L1" which caches an SSD or RAID-SSD, HDD or RAID-HDD -- to RAM. You can cache an "L2" configuration of paired SSD/HDD to RAM.

Primo works to providing L1 and L2 caching for non-Samsung drives, in harmony with RAPID caching for the 840 and 850 drive. Or, you can simply disable RAPID for the Sammy and use Primo instead.

If you have a 16GB kit or kits installed, and you have certain usage patterns which don't take advantage of it, you can get some extra value this way with Primo's L1 caching.

It has been argued that spending money on a 60GB drive is more wasteful than buying a larger drive, and that it's better to use even a 60GB unit for an NTFS storage volume place for storage, or even part of a RAID. But some very large HDDs can cost $200 or more (last I looked!) and so even a modestly-sized SSD would have benefit and not add much more than $40 to the equation.

It may have been the poor man's SSD, but it is no less useful for better enabling large HDD capacity when anything over 1TB as an SSD would be hard to find unless it were Intel's recent NVMe card of 1.2GB at something as high as $700.

You don't add anything to power-consumption of any consequence. If the system is stable, the caching should be reliable, or so I have found. And caching has been done in hardware configurations from much earlier days in computing history.

That's a great breakdown of some of the concerns, pros/cons. While SRT worked well for my scenario, I'm fickle and I've already moved on. I'm going all SSD with 2x 1tb RAID0.

 

[BonzaiDuck]

That's a great breakdown of some of the concerns, pros/cons. While SRT worked well for my scenario, I'm fickle and I've already moved on. I'm going all SSD with 2x 1tb RAID0.

. . . and you can cache that to RAM with Primo . . . and be sure that TRIM is implemented if it's implemented for the RAID.

 

[voodoodrul]

. . . and you can cache that to RAM with Primo . . . and be sure that TRIM is implemented if it's implemented for the RAID.

I'm pretty sure TRIM is enabled. X79 with latest UEFI and RST drivers. I'll have to check out Primo. It sounds like a great solution.

 

[BonzaiDuck]

I'm pretty sure TRIM is enabled. X79 with latest UEFI and RST drivers. I'll have to check out Primo. It sounds like a great solution.

I can see how you might spring for 2x 1TB SSDs for that board, BIOS and processor. But no matter. if you decide to put a higher-capacity GPT HDD in that box, the caching COULD be some advantage if you're pulling games and other items from it.

You wouldn't need caching, nor would you need SSDs for video captures, movies and so on. Even if you cached such a drive, I think the software would manage it to avoid cluttering the cache with large files you may only read one time here and there.

But the PRimo is a tool worth acquiring even if you're not sure how it might be used on that or another rig in the future. It's sort of a Swiss Army knife of caching options. With Samsung drives, you can kick RAPID out the door if you're configured in AHCI mode even to permit it, and you can use Primo with a medley of AHCI and RAID storage modes and controllers. You could use ISRT with your RAID-mode configuration, but it wouldn't do you any good to use an SSD to cache a RAID of SSDs. The only advantage left to reap would be RAM-caching. With Primo you can; with RAPID and RAID -- you can't.

At least with Primo, you can have many caching tasks all working at the same time. You could use it to RAM-cache an SSD while SSD-caching (with RAM-caching) an HDD or array thereof. And unlike ISRT, you can RAM-cache an HDD or HDD array directly.

 

[SickBeast]

Guys I have 2TB of games being enhanced with a 64gb SRT cache and it's absolutely great. After the first time loading them the load times are amazing, almost as fast as an SSD. I am a really big fan of this concept!

 

[AlienTech]