Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Ben Alex]

On Tue, Feb 2, 2016 at 5:19 AM, Tinker  wrote:
>  1) I need some SSD storage but don't like that it could break together - I
> mean, a bug in your system will feed your SSD at full bandwidth for ~7h-7
> days, it's completely fried - that's not OK, so putting a "redundance layer"
> in the from of an underlying magnet storage layer is really justified.
>
>  2) I need some bulk storage, and I want the terabytes to be really cheap so
> that i NEVER will run out of archival space. An 8TB magnet HDD costs in the
> range USD 500.

Last month I purchased another 400 TB of magnetic and SSD storage, so
with that recent research in mind:

* SSD models are differentiated by write endurance, interface
(SATA/SAS vs NVMe), and consumer vs data centre grade. The latter
offer continuous (24x7) workload latency guarantees and work well in
RAID configurations as there is minimal latency variability between
units. I'm unsure of the OpenBSD NVMe status, but you need NVMe if you
want to pull the rated ~2500 MB/sec out of NVMe units. Sticking with
SATA/SAS SSD means closer to 1/5th that maximum read performance,
although that may well be enough (and will save you a lot of money,
too). I'd avoid doing RAID with consumer grade SSDs if you have high
throughput expectations.

* Some magnetic drives are now also being rated with annual workload
limits and have associated warranty implications. See for example
http://www.seagate.com/au/en/products/enterprise-servers-storage/nearline-storage/.
Be careful to review the data sheets so you don't have future warranty
claims rejected.

I've found it's easy to KISS by grouping by file type (eg immutable or
mutable or append-only, sequentially accessed vs randomly accessed,
main reader bottleneck being CPU/RAM or IO etc) and putting them in
optimal primary and backup locations accordingly. I find the idea of
transparent storage tiers undesirable, as there's no way I can reason
about that and guarantee consistent throughput and latency results
(let alone how to recover when a few drives out of the 60+ fail, or a
non-JBOD controller dies).

Are you able to share more about your storage requirements (capacity,
sequential throughput, IO latency, resiliency, target chassis details
etc) so we can offer suggestions?

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Adam Thompson]

On 16-02-01 12:19 PM, Tinker wrote:

My purpose with asking for SSD-accelerated HDD was DOUBLE:

 1) I need some SSD storage but don't like that it could break 
together - I mean, a bug in your system will feed your SSD at full 
bandwidth for ~7h-7 days, it's completely fried - that's not OK, so 
putting a "redundance layer" in the from of an underlying magnet 
storage layer is really justified.


...so what?  I don't understand what your concern is here.  If you buy a 
batch of HDDs from the same lot, they'll probably all die around the 
same time, too.  I don't think I understand what you're trying to say.


If you're worried about SSD write endurance, I'd say... don't.  Or buy 
better-quality SSDs ;-).


See http://ssdendurancetest.com/  for real-world stress-test data. 
Especially 
http://ssdendurancetest.com/ssd-endurance-test-report/Intel-SSD-520-60.


The Intel DC P3700 series should last about 1.5yrs in an absolutely 
worst-case scenario.  Even the worst-case DC series I could find should 
still last about a month and a half under murderous stress-test conditions.


http://estimator.intel.com/ssdendurance/

This report 
(http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead) 
confirms that even if you completely fill an SSD, that's no big deal.


If your application has a "bug" it's unlikely the sort of bug that would 
fill the entire SSD, erase it all, fill it again, erase it all again, 
etc... and most SSDs can handle ~3000 full-device writes nowadays.


Also remember to factor in the fact that UFS/UFS2 doesn't (usually) 
saturate a block device with I/O write requests.  Maybe if it was just 
writing to a single enormous file it might, but could that actually 
happen in your situation?



2) I need some bulk storage, and I want the terabytes to be really 
cheap so that i NEVER will run out of archival space. An 8TB magnet 
HDD costs in the range USD 500.


Here, I like it to be stored "symmetrically" with how I store the 
other stuff, that is having separate disks, directories, mount points 
etc. for the two doesn't really appeal to me in this particular case -


Simply knowing that the less frequently accessed data will be 
taken from magnet and the more frequently accessed data from SSD seems 
both convenient and practical for my usecase, and, I'll try to have 
SSD volume to cover for *MORE THAN ALL* of my frequently stored data.


Perhaps knowing the prioritization algorithm as to be able to 
calculate more closely what's in the SSD and what's on the HDD only 
would make some sense, BUT, training it by telling it what's to load 
fast using "cat `find the-relevant-data/` > /dev/null" single-shot and 
perhaps via crontab, should deliver really well.


Cheap storage is a valid argument.  HDD vs SSD is still easily an order 
of magnitude difference in price.


So go run FreeNAS (or TrueNAS, or Solaris, or FreeBSD, or even 
Linux...), run ZFS with both a L2ARC and ZIL device on fast SSD, and 
remote-mount the directory.  You even have a choice of protocols :-).  
(NFS or iSCSI.  I suspect you'd want to use NFS, but YMMV.)


Short answer: I don't think any part of OpenBSD does what you're asking, 
natively.  Some supported hardware devices (like the MegaRAID Cachecade, 
et al.) do this for you.  But at that point, what's the difference 
between having the disks hooked up to some speciality hardware in an 
OpenBSD box, versus having the disks hooked up to generic, not-special 
hardware on a non-OpenBSD box? (Particularly given that UFS/UFS2 on 
OpenBSD isn't exactly known for its award-winning performance in the 
first place?)


FYI, even if Intel SRT was available on a Xeon board, you'd still be out 
of luck, because it requires device driver support  - it relies on the 
Intel fake-raid technology which, IIRC, is not supported at all under 
OpenBSD.


I'd also like to see something like this available in OpenBSD's VFS 
layer, but I'm not holding my breath.


IIRC there was some interest in integrating Hammer/Hammer2 into OpenBSD 
instead of ZFS due to licensing issues, but even Hammer2 doesn't appear 
to have tiered storage in its feature list.


Some more random thoughts:
- the Dell H800 supports up to 1GB NVRAM, which is just a CacheCade 
implementation.
- CacheVault is the newer version of CacheCade (AFAICT), and is 
supported on newer MegaRAID cards.  See 
http://www.avagotech.com/products/server-storage/raid-controllers/cache-protection#overview 
for some pretty skimpy info.
- moving your data from HDD to SSD isn't going to dramatically speed up 
READ operations.  Carefully examine the specsheets on both the HDDs and 
SSDs and compare read bandwidths.  Access time (latency) is where SSDs 
are useful, along with acting as write-back caches.
- Areca raid controllers support up to 8GB of cache and a sh*tload of 
SAS ports; this might be good enough for your needs - have a look.



Either iSCSI or NFS against a ZFS-based NAS is probably still your best 
bets 

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Janne Johansson]

2016-01-31 9:16 GMT+01:00 Tinker :

> This could be made in software with benefit, as a Softraid patch.
> So the frequently accessed stuff ends up cached on the SSD for faster read
> speed.
> There is some hardware solution, e.g. Intel made the
> http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
> using the "Nytro MegaRAID" chip.
> Also in the past there was a "Adaptec MaxIQ". Those are the only two "Raid
> controller cache" hardware solutions I am aware of, do you know any more?
>
>
Intel Z68 motherboards also have this in hardware. A bit tiresome to set up
for bootdrives (since the disk type changes from normal SATA to raid)
but should be transparent to the OS after it is set up.

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Janne Johansson]

I saw it on a desktop, didn't think to see if it was ever used or not on
motherboards for other types of machines, I just assumed that Z68 could be
used on other places also.


2016-02-01 11:00 GMT+01:00 Tinker :

> On 2016-02-01 16:33, Janne Johansson wrote:
>
>> 2016-01-31 9:16 GMT+01:00 Tinker :
>>
>> This could be made in software with benefit, as a Softraid patch.
>>> So the frequently accessed stuff ends up cached on the SSD for faster
>>> read
>>> speed.
>>> There is some hardware solution, e.g. Intel made the
>>>
>>> http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
>>> using the "Nytro MegaRAID" chip.
>>> Also in the past there was a "Adaptec MaxIQ". Those are the only two
>>> "Raid
>>> controller cache" hardware solutions I am aware of, do you know any more?
>>>
>>>
>>> Intel Z68 motherboards also have this in hardware. A bit tiresome to set
>> up
>> for bootdrives (since the disk type changes from normal SATA to raid)
>> but should be transparent to the OS after it is set up.
>>
>
> Thanks for mentioning, however, this tech (called "Intel Smart Response")
> is a laptop/desktop thing only currently isn't it, you don't see it on any
> 1-2-4x Xeon:s at least now right?
>
>


-- 
May the most significant bit of your life be positive.

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

On 2016-02-01 16:33, Janne Johansson wrote:

2016-01-31 9:16 GMT+01:00 Tinker :


This could be made in software with benefit, as a Softraid patch.
So the frequently accessed stuff ends up cached on the SSD for faster 
read

speed.
There is some hardware solution, e.g. Intel made the
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
using the "Nytro MegaRAID" chip.
Also in the past there was a "Adaptec MaxIQ". Those are the only two 
"Raid
controller cache" hardware solutions I am aware of, do you know any 
more?



Intel Z68 motherboards also have this in hardware. A bit tiresome to 
set up

for bootdrives (since the disk type changes from normal SATA to raid)
but should be transparent to the OS after it is set up.


Thanks for mentioning, however, this tech (called "Intel Smart 
Response") is a laptop/desktop thing only currently isn't it, you don't 
see it on any 1-2-4x Xeon:s at least now right?

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[patric conant]

On Sun, Jan 31, 2016 at 8:42 PM, Tinker  wrote:

> Patrick,
>
> On 2016-02-01 07:10, Patrick Dohman wrote:
>
>> There is some hardware solution, e.g. Intel made the
>>>
>>
>>
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB04
>> 0LX using the "Nytro MegaRAID" chip.
>>
>>>
>>> Someone would need to port its driver to OpenBSD.
>>>
>>> Also in the past there was a "Adaptec MaxIQ". Those are the only two
>>> "Raid
>>>
>> controller cache" hardware solutions I am aware of, do you know any more?
>>
>>>
>>>
>>>
>>>
>> Some of the MegaRaid cards feature cache cade.
>>
>
> Do you know any MegaRaid that a) supports that, b) is modern and not
> archaic, and c) is supported by OpenBSD?
>
> Essentially disk cache is written to SSD before being “copied” to
spinning
>> disk.
>>
>
> I was mostly considering read acceleration.
>
> (
>
>> Keep in mind DRAM based cache can improve performance when implemented in
>> conjunction with hardware write back.
>>
>
> Sure.
>
> Also magnetic disk & SSD with super cap / fault tolerant on disk cache can
>> seed up I/O significantly..
>>
>
> Can you give a practical example of this?
> )
>
> Thanks,
> Tinker
>
>
Why can't the solution be all flash? $400 for 1 TB flash, * 7 sata ports on
a decent $100 Motherboard, gets you 7TB of flash for under $3000

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[andrew fabbro]

On Mon, Feb 1, 2016 at 8:16 AM, patric conant 
wrote:

> Why can't the solution be all flash? $400 for 1 TB flash, * 7 sata ports on
> a decent $100 Motherboard, gets you 7TB of flash for under $3000
>

Well, yes, and for a few hundred thousand you can get persistent DRAM
fusion-io.

OTOH, you can get 4TB SATA drives for $250.

The OP was just pointing out that SSD-acceleted (aka SSD-cached) SATA/SAS
is very common in Win/Lin/OSX and was wondering what the status is on
OpenBSD.


-- 
andrew fabbro
and...@fabbro.org

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

On 2016-02-01 22:13, andrew fabbro wrote:
On Mon, Feb 1, 2016 at 8:16 AM, patric conant 


wrote:

Why can't the solution be all flash? $400 for 1 TB flash, * 7 sata 
ports on

a decent $100 Motherboard, gets you 7TB of flash for under $3000



Well, yes, and for a few hundred thousand you can get persistent DRAM
fusion-io.

OTOH, you can get 4TB SATA drives for $250.

The OP was just pointing out that SSD-acceleted (aka SSD-cached) 
SATA/SAS

is very common in Win/Lin/OSX and was wondering what the status is on
OpenBSD.



My purpose with asking for SSD-accelerated HDD was DOUBLE:

 1) I need some SSD storage but don't like that it could break together 
- I mean, a bug in your system will feed your SSD at full bandwidth for 
~7h-7 days, it's completely fried - that's not OK, so putting a 
"redundance layer" in the from of an underlying magnet storage layer is 
really justified.


 2) I need some bulk storage, and I want the terabytes to be really 
cheap so that i NEVER will run out of archival space. An 8TB magnet HDD 
costs in the range USD 500.


Here, I like it to be stored "symmetrically" with how I store the 
other stuff, that is having separate disks, directories, mount points 
etc. for the two doesn't really appeal to me in this particular case -


Simply knowing that the less frequently accessed data will be taken 
from magnet and the more frequently accessed data from SSD seems both 
convenient and practical for my usecase, and, I'll try to have SSD 
volume to cover for *MORE THAN ALL* of my frequently stored data.


Perhaps knowing the prioritization algorithm as to be able to 
calculate more closely what's in the SSD and what's on the HDD only 
would make some sense, BUT, training it by telling it what's to load 
fast using "cat `find the-relevant-data/` > /dev/null" single-shot and 
perhaps via crontab, should deliver really well.



Tinker

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Patrick Dohman]

> There is some hardware solution, e.g. Intel made the
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB04
0LX using the "Nytro MegaRAID" chip.
>
> Someone would need to port its driver to OpenBSD.
>
> Also in the past there was a "Adaptec MaxIQ". Those are the only two "Raid
controller cache" hardware solutions I am aware of, do you know any more?
>
>
>

Some of the MegaRaid cards feature cache cade.

Essentially disk cache is written to SSD before being “copied” to spinning
disk.

Keep in mind DRAM based cache can improve performance when implemented in
conjunction with hardware write back.

Also magnetic disk & SSD with super cap / fault tolerant on disk cache can
seed up I/O significantly..

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

Patrick,

To sum up, neat to see that (from what we can see without having tested 
it,) there is (even inexpensive) hardware for this on the market, neat!



My last question related to this would be, what if drives start breaking 
down (storage or CacheCade drives), would the OpenBSD system learn to 
know somehow, is there any tool or would the MFI driver report it in the 
syslog?


(So you as admin will know and can go and shut it down and replace the 
broken drive.)





On 2016-02-01 11:14, Patrick Dohman wrote:

Do you know any MegaRaid that a) supports that, b) is modern and not

archaic, and c) is supported by OpenBSD?




It appears the MFI driver provides support for the MegaRAID SAS 9260-8i

Pleas note I’ve not tested the 9260-8i on openbsd

http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man4/mfi.4


My current understanding is that Cache Cade is licensed add-on for the 
9260-8i

that can be configured in the RAID bios.


Without having tried it myself, I share your understanding.

You buy a separate license that is distributed in the form of a tiny PCB 
that you mount on the controller card.



http://www.avagotech.com/products/server-storage/raid-controllers/megaraid-ca
checade-pro-software#specifications


http://www.avagotech.com/products/server-storage/raid-controllers/megaraid-sa
s-9260-8i




I was mostly considering read acceleration.


Read Ahead caching is supported by the 9260-8i this essentially caches 
to
onboard DRAM contiguous blocks if the controllers algorithm determines 
they

will be needed.


What I see is that it will use the whole SSD for read acceleration.

BUT, the current version (that is CacheCadePro 2.0) only supports "512GB 
of CacheCade [i.e. read acceleration] per controller".


Luckily, 
http://docs.avagotech.com/docs-and-downloads/advanced-software/lsi-megaraid-cachecade-software/CacheCadePro2_TechBrief.pdf 
points out that an "upcoming release" will support ">2TB".


I emailed them and asked for clarification.





Can you give a practical example of this?
)


A RAID 10 with four disks running enterprise Intel SSD disk drives with
MegaRAID disk caching enabled, Essentially the Intel Enterprise SSD on 
board

cache augments the NAND flash. Fault tolerance is provided by a
“capacitor†that flushes the cache to disk after a power loss..


Right - and now we see that actual read acceleration of a magnet HDD 
using SSD is possible, that is what CacheCade is about.

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

Patrick,

On 2016-02-01 07:10, Patrick Dohman wrote:

There is some hardware solution, e.g. Intel made the

http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB04
0LX using the "Nytro MegaRAID" chip.


Someone would need to port its driver to OpenBSD.

Also in the past there was a "Adaptec MaxIQ". Those are the only two 
"Raid
controller cache" hardware solutions I am aware of, do you know any 
more?






Some of the MegaRaid cards feature cache cade.


Do you know any MegaRaid that a) supports that, b) is modern and not 
archaic, and c) is supported by OpenBSD?


Essentially disk cache is written to SSD before being “copied” to 
spinning

disk.


I was mostly considering read acceleration.

(
Keep in mind DRAM based cache can improve performance when implemented 
in

conjunction with hardware write back.


Sure.

Also magnetic disk & SSD with super cap / fault tolerant on disk cache 
can

seed up I/O significantly..


Can you give a practical example of this?
)

Thanks,
Tinker

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Patrick Dohman]

> Do you know any MegaRaid that a) supports that, b) is modern and not
archaic, and c) is supported by OpenBSD?
>

It appears the MFI driver provides support for the MegaRAID SAS 9260-8i

Pleas note I’ve not tested the 9260-8i on openbsd

http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man4/mfi.4


My current understanding is that Cache Cade is licensed add-on for the 9260-8i
that can be configured in the RAID bios.

http://www.avagotech.com/products/server-storage/raid-controllers/megaraid-ca
checade-pro-software#specifications


http://www.avagotech.com/products/server-storage/raid-controllers/megaraid-sa
s-9260-8i


>
> I was mostly considering read acceleration.

Read Ahead caching is supported by the 9260-8i this essentially caches to
onboard DRAM contiguous blocks if the controllers algorithm determines they
will be needed.

>
> Can you give a practical example of this?
> )

A RAID 10 with four disks running enterprise Intel SSD disk drives with
MegaRAID disk caching enabled, Essentially the Intel Enterprise SSD on board
cache augments the NAND flash. Fault tolerance is provided by a
“capacitor” that flushes the cache to disk after a power loss..

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

If there is nothing like this implemented in software in OpenBSD,

 * If someone implemented it, would there be interest to actually 
include the patch in OpenBSD?


 * Could a direct personal donation (separate from the normal donations 
to the OpenBSD project) to a developer be of use for making this happen, 
if so how big a donation, of what value would USD 1,000 be in 
proportion?


   Not sure right now but next 12 months I could consider this, if you 
have any ideas about who feel free to respond or PM or anything you 
like.




On 2016-01-31 16:16, Tinker wrote:

This could be made in software with benefit, as a Softraid patch.

So the frequently accessed stuff ends up cached on the SSD for faster
read speed.


ZFS on FreeBSD etc. does it in its "ARC"/"ARC2L" feature?


There is some hardware solution, e.g. Intel made the
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
using the "Nytro MegaRAID" chip.

Someone would need to port its driver to OpenBSD.

Also in the past there was a "Adaptec MaxIQ". Those are the only two
"Raid controller cache" hardware solutions I am aware of, do you know
any more?



(Was not sure if this belonged on tech@ or misc@, any clarification
for me to never more crosspost please let me know)

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Tinker]

Ah, I now understand that this problem is mindbogglingly complex because 
of tons and tons of work needed to make it work, including the storage 
format on the SSD cache, and tools for "fsck":ing it etc etc. In a way 
that maybe answered my question, thanks!



On 2016-01-31 19:00, Tinker wrote:

If there is nothing like this implemented in software in OpenBSD,

 * If someone implemented it, would there be interest to actually
include the patch in OpenBSD?

 * Could a direct personal donation (separate from the normal
donations to the OpenBSD project) to a developer be of use for making
this happen, if so how big a donation, of what value would USD 1,000
be in proportion?

   Not sure right now but next 12 months I could consider this, if you
have any ideas about who feel free to respond or PM or anything you
like.



On 2016-01-31 16:16, Tinker wrote:

This could be made in software with benefit, as a Softraid patch.

So the frequently accessed stuff ends up cached on the SSD for faster
read speed.


ZFS on FreeBSD etc. does it in its "ARC"/"ARC2L" feature?


There is some hardware solution, e.g. Intel made the
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
using the "Nytro MegaRAID" chip.

Someone would need to port its driver to OpenBSD.

Also in the past there was a "Adaptec MaxIQ". Those are the only two
"Raid controller cache" hardware solutions I am aware of, do you know
any more?



(Was not sure if this belonged on tech@ or misc@, any clarification
for me to never more crosspost please let me know)

Re: Can I accelerate my magnet HDD using a SSD in any way?? E.g. softraid patch/ARC, dedicated hardware e.g. Intel RCS25ZB040LX="Nytro MegaRAID", anything

[Karel Gardas]

IMHO it's for misc.

So, yes, feel free to donate to either OpenBSD foundation or directly
to interested developer. I'm sure your donation will be appreciated.

In your list you omitted two other options how to speed your hdd access:

- buy more RAM and increase caching, on AMD64 it would probably need
to use IOMMU so either new development or resurrection of this from
the past would be needed. This should help you with read.

- sponsor WAPBL enhancements to support data logging and external
journal. This should speed your write access.

If you are interested in softraid, then perhaps some funding of fixes
which would allow running several softraid drives on top of another
would be great way to reuse your specific caching softraid discipline
with whatever softraid OpenBSD supports now.

And do not forget that development takes time so I would strongly
recommend you to contact OpenBSD foundation just on Monday morning and
send them your money contribution with a plea for work -- especially
if you like to use that in 12 month timeframe in production
environment.

On Sun, Jan 31, 2016 at 12:45 PM, Tinker  wrote:
> Ah, I now understand that this problem is mindbogglingly complex because of
> tons and tons of work needed to make it work, including the storage format
> on the SSD cache, and tools for "fsck":ing it etc etc. In a way that maybe
> answered my question, thanks!
>
>
>
> On 2016-01-31 19:00, Tinker wrote:
>>
>> If there is nothing like this implemented in software in OpenBSD,
>>
>>  * If someone implemented it, would there be interest to actually
>> include the patch in OpenBSD?
>>
>>  * Could a direct personal donation (separate from the normal
>> donations to the OpenBSD project) to a developer be of use for making
>> this happen, if so how big a donation, of what value would USD 1,000
>> be in proportion?
>>
>>Not sure right now but next 12 months I could consider this, if you
>> have any ideas about who feel free to respond or PM or anything you
>> like.
>>
>>
>>
>> On 2016-01-31 16:16, Tinker wrote:
>>>
>>> This could be made in software with benefit, as a Softraid patch.
>>>
>>> So the frequently accessed stuff ends up cached on the SSD for faster
>>> read speed.
>>>
>>>
>>> ZFS on FreeBSD etc. does it in its "ARC"/"ARC2L" feature?
>>>
>>>
>>> There is some hardware solution, e.g. Intel made the
>>>
>>> http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
>>> using the "Nytro MegaRAID" chip.
>>>
>>> Someone would need to port its driver to OpenBSD.
>>>
>>> Also in the past there was a "Adaptec MaxIQ". Those are the only two
>>> "Raid controller cache" hardware solutions I am aware of, do you know
>>> any more?
>>>
>>>
>>>
>>> (Was not sure if this belonged on tech@ or misc@, any clarification
>>> for me to never more crosspost please let me know)