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From Sergey Kozlov <skoz...@gridgain.com>
Subject Re: Ignite as distributed file storage
Date Tue, 03 Jul 2018 07:39:58 GMT
Dmitriy

You're right that that large objects storing should be optmized.

Let's assume the large object means the regular object having large fields
and such fileds won't be used for comparison thus we can do not restore the
BLOB fields in offheap page memory e.g for sql queries if select doesn't
include them explicitly. It can reduce page eviction and speed up the
perfomance and make less chance to get OOM.



On Tue, Jul 3, 2018 at 1:06 AM, Dmitriy Setrakyan <dsetrakyan@apache.org>
wrote:

> To be honest, I am not sure if we need to kick off another file system
> storage discussion in Ignite. It sounds like a huge effort and likely will
> not be productive.
>
> However, I think an ability to store large objects will make sense. For
> example, how do I store a 10GB blob in Ignite cache? Most likely we have to
> have a separate memory or disk space, allocated for blobs only. We also
> need to be able to efficiently transfer a 10GB Blob object over the network
> and store it off-heap right away, without bringing it into main heap memory
> (otherwise we would run out of memory).
>
> I suggest that we create an IEP about this use case alone and leave the
> file system for the future discussions.
>
> D.
>
> On Mon, Jul 2, 2018 at 6:50 AM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>
> > Pavel,
> >
> > Thank you. I'll wait for feature comparison and concrete use cases,
> because
> > for me this feature still sounds too abstract to judge whether product
> > would benefit from it.
> >
> > On Mon, Jul 2, 2018 at 3:15 PM Pavel Kovalenko <jokserfn@gmail.com>
> wrote:
> >
> > > Dmitriy,
> > >
> > > I think we have a little miscommunication here. Of course, I meant
> > > supporting large entries / chunks of binary data. Internally it will be
> > > BLOB storage, which can be accessed through various interfaces.
> > > "File" is just an abstraction for an end user for convenience, a
> wrapper
> > > layer to have user-friendly API to directly store BLOBs. We shouldn't
> > > support full file protocol support with file system capabilities. It
> can
> > be
> > > added later, but now it's absolutely unnecessary and introduces extra
> > > complexity.
> > >
> > > We can implement our BLOB storage step by step. The first thing is
> > > core functionality and support to save large parts of binary objects to
> > it.
> > > "File" layer, Web layer, etc. can be added later.
> > >
> > > The initial IGFS design doesn't have good capabilities to have a
> > > persistence layer. I think we shouldn't do any changes to it, this
> > project
> > > as for me is almost outdated. We will drop IGFS after implementing File
> > > System layer over our BLOB storage.
> > >
> > > Vladimir,
> > >
> > > I will prepare a comparison with other existing distributed file
> storages
> > > and file systems in a few days.
> > >
> > > About usage data grid, I never said, that we need transactions, sync
> > backup
> > > and etc. We need just a few core things - Atomic cache with
> persistence,
> > > Discovery, Baseline, Affinity, and Communication.
> > > Other things we can implement by ourselves. So this feature can develop
> > > independently of other non-core features.
> > > For me Ignite way is providing to our users a fast and convenient way
> to
> > > solve their problems with good performance and durability. We have the
> > > problem with storing large data, we should solve it.
> > > About other things see my message to Dmitriy above.
> > >
> > > вс, 1 июл. 2018 г. в 9:48, Dmitriy Setrakyan <dsetrakyan@apache.org>:
> > >
> > > > Pavel,
> > > >
> > > > I have actually misunderstood the use case. To be honest, I thought
> > that
> > > > you were talking about the support of large values in Ignite caches,
> > e.g.
> > > > objects that are several megabytes in cache.
> > > >
> > > > If we are tackling the distributed file system, then in my view, we
> > > should
> > > > be talking about IGFS and adding persistence support to IGFS (which
> is
> > > > based on HDFS API). It is not clear to me that you are talking about
> > > IGFS.
> > > > Can you confirm?
> > > >
> > > > D.
> > > >
> > > >
> > > > On Sat, Jun 30, 2018 at 10:59 AM, Pavel Kovalenko <
> jokserfn@gmail.com>
> > > > wrote:
> > > >
> > > > > Dmitriy,
> > > > >
> > > > > Yes, I have approximate design in my mind. The main idea is that
we
> > > > already
> > > > > have distributed cache for files metadata (our Atomic cache), the
> > data
> > > > flow
> > > > > and distribution will be controlled by our AffinityFunction and
> > > Baseline.
> > > > > We're already have discovery and communication to make such local
> > files
> > > > > storages to be synced. The files data will be separated to large
> > blocks
> > > > > (64-128Mb) (which looks very similar to our WAL). Each block can
> > > contain
> > > > > one or more file chunks. The tablespace (segment ids, offsets and
> > etc.)
> > > > > will be stored to our regular page memory. This is key ideas to
> > > implement
> > > > > first version of such storage. We already have similiar components
> in
> > > our
> > > > > persistence, so this experience can be reused to develop such
> > storage.
> > > > >
> > > > > Denis,
> > > > >
> > > > > Nothing significant should be changed at our memory level. It will
> be
> > > > > separate, pluggable component over cache. Most of the functions
> which
> > > > give
> > > > > performance boost can be delegated to OS level (Memory mapped
> files,
> > > DMA,
> > > > > Direct write from Socket to disk and vice versa). Ignite and File
> > > Storage
> > > > > can develop independetly of each other.
> > > > >
> > > > > Alexey Stelmak, which has a great experience with developing such
> > > systems
> > > > > can provide more low level information about how it should look.
> > > > >
> > > > > сб, 30 июн. 2018 г. в 19:40, Dmitriy Setrakyan <
> > dsetrakyan@apache.org
> > > >:
> > > > >
> > > > > > Pavel, it definitely makes sense. Do you have a design in mind?
> > > > > >
> > > > > > D.
> > > > > >
> > > > > > On Sat, Jun 30, 2018, 07:24 Pavel Kovalenko <jokserfn@gmail.com>
> > > > wrote:
> > > > > >
> > > > > > > Igniters,
> > > > > > >
> > > > > > > I would like to start a discussion about designing a new
> feature
> > > > > because
> > > > > > I
> > > > > > > think it's time to start making steps towards it.
> > > > > > > I noticed, that some of our users have tried to store large
> > > > homogenous
> > > > > > > entries (> 1, 10, 100 Mb/Gb/Tb) to our caches, but without
big
> > > > success.
> > > > > > >
> > > > > > > IGFS project has the possibility to do it, but as for me
it has
> > one
> > > > big
> > > > > > > disadvantage - it's in-memory only, so users have a strict
size
> > > limit
> > > > > of
> > > > > > > their data and have data loss problem.
> > > > > > >
> > > > > > > Our durable memory has a possibility to persist a data
that
> > doesn't
> > > > fit
> > > > > > to
> > > > > > > RAM to disk, but page structure of it is not supposed to
store
> > > large
> > > > > > pieces
> > > > > > > of data.
> > > > > > >
> > > > > > > There are a lot of projects of distributed file systems
like
> > HDFS,
> > > > > > > GlusterFS, etc. But all of them concentrate to implement
> > high-grade
> > > > > file
> > > > > > > protocol, rather than user-friendly API which leads to
high
> entry
> > > > > > threshold
> > > > > > > to start implementing something over it.
> > > > > > > We shouldn't go in this way. Our main goal should be providing
> to
> > > > user
> > > > > > easy
> > > > > > > and fast way to use file storage and processing here and
now.
> > > > > > >
> > > > > > > If take HDFS as closest possible by functionality project,
we
> > have
> > > > one
> > > > > > big
> > > > > > > advantage against it. We can use our caches as files metadata
> > > storage
> > > > > and
> > > > > > > have the infinite possibility to scale it, while HDFS is
> bounded
> > by
> > > > > > > Namenode capacity and has big problems with keeping a large
> > number
> > > of
> > > > > > files
> > > > > > > in the system.
> > > > > > >
> > > > > > > We achieved very good experience with persistence when
we
> > developed
> > > > our
> > > > > > > durable memory, and we can couple together it and experience
> with
> > > > > > services,
> > > > > > > binary protocol, I/O and start to design a new IEP.
> > > > > > >
> > > > > > > Use cases and features of the project:
> > > > > > > 1) Storing XML, JSON, BLOB, CLOB, images, videos, text,
etc
> > without
> > > > > > > overhead and data loss possibility.
> > > > > > > 2) Easy, pluggable, fast and distributed file processing,
> > > > > transformation
> > > > > > > and analysis. (E.g. ImageMagick processor for images
> > > transformation,
> > > > > > > LuceneIndex for texts, whatever, it's bounded only by your
> > > > > imagination).
> > > > > > > 3) Scalability out of the box.
> > > > > > > 4) User-friendly API and minimal steps to start using this
> > storage
> > > in
> > > > > > > production.
> > > > > > >
> > > > > > > I repeated again, this project is not supposed to be a
> high-grade
> > > > > > > distributed file system with full file protocol support.
> > > > > > > This project should primarily focus on target users, which
> would
> > > like
> > > > > to
> > > > > > > use it without complex preparation.
> > > > > > >
> > > > > > > As for example, a user can deploy Ignite with such storage
and
> > > > > web-server
> > > > > > > with REST API as Ignite service and get scalable, performant
> > image
> > > > > server
> > > > > > > out of the box which can be accessed using any programming
> > > language.
> > > > > > >
> > > > > > > As a far target goal, we should focus on storing and
> processing a
> > > > very
> > > > > > > large amount of the data like movies, streaming, which
is the
> big
> > > > trend
> > > > > > > today.
> > > > > > >
> > > > > > > I would like to say special thanks to our community members
> > Alexey
> > > > > > Stelmak
> > > > > > > and Dmitriy Govorukhin which significantly helped me to
put
> > > together
> > > > > all
> > > > > > > pieces of that puzzle.
> > > > > > >
> > > > > > > So, I want to hear your opinions about this proposal.
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>



-- 
Sergey Kozlov
GridGain Systems
www.gridgain.com

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