The 6TB limit (or recommendation as described) is when you're using TSM's dedup
capabilities on the filepool, not when using the DD dedup.
Setup sounds great as long as your TSM system doesnt suffer from a logical
error (since logical errors will be deduplicated from your primary DD to your
secondary DD). In that case, you risk loosing data. Since TSM verifies data
being written between primary and copypools, the risk of duplicating the
logical error is much less likely to happen when doing a backup storagepool
compared to using DD replication (which doesnt take in account TSM logical
errors). This would also be the case if your DD environment suffers a hash
conflict (not likely to happen, but still a real threat).
I'm guessing you're only using your DD setup for TSM then?
Best Regards
Daniel
Daniel Sparrman
Exist i Stockholm AB
Växel: 08-754 98 00
Fax: 08-754 97 30
daniel.sparrman AT exist DOT se
http://www.existgruppen.se
Posthusgatan 1 761 30 NORRTÄLJE
-----"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> skrev: -----
Till: ADSM-L AT VM.MARIST DOT EDU
Från: Rick Adamson <RickAdamson AT WINN-DIXIE DOT COM>
Sänt av: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
Datum: 09/28/2011 15:17
Ärende: Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] vtl versus file
systems for pirmary pool
Really appreciate everyone's feedback.
In an attempt to clear up a few points and questions that Daniel (and others)
brought up and something that has surprisingly been left out of the
conversation is DD's replication capabilities.
Since TSM uses the infamous incremental forever approach, very well I may add,
de-duplication is a plus, but being able to utilize an efficient method to get
the data to a DR site as an exact duplicate of your production TSM data is
huge. Our DD system gets an average of 10:1 de-dup ratio on storage across all
data types. Comparatively, my main-frame counterpart gets about 35:1, which
emphasizes the job TSM incr. forever does.
If there is a 6tb limit on file device storage, IBM said nothing about it when
they approved our design, and I have several that are well above that and
performance could not be better. In reference to the LAN vs. Lan-free, the only
data that traverses the LAN is from client to TSM server, except special needs
systems, VMware, Exchange, etc.
The TSM servers have a 10gb FcoE back end network that is used strictly for the
data transport between TSM and DD (plus the special cases mentioned above). The
storage hierarchy uses fibre attached EMC Clarrion for the random-access disk
pools which then migrates to the DD880 where deduplication and compression
takes place.
Once in the DD880 all data including the TSM server database backups are
replicated to another DD device at our DR facility where I have virtual TSM
servers as warm stand-bys. In the case we declare a disaster, or a BCP test,
the TSM databases are restored to the warm TSM servers and I'm up and running
with all of my TSM servers in under an hour. (yes, I've tested it). As far as
TSM support, there comments were that they will not support the replication
component simply because that piece is DD not IBM.
Lastly, I guess I always looked at the VTL choice as being something additional
to maintain (define drives, paths, etc). File device class for our operation
just works, and works, and works :)
As always, questions and comments appreciated.
~Rick Adamson
JaX, Fl.
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Hans Christian Riksheim
Sent: Wednesday, September 28, 2011 3:57 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] vtl versus file
systems for pirmary pool
This 6 TB supported limit for deduplicated FILEPOOL does this limit
apply when one does client side deduplication only?
Just wondering since I have just set up a 30 TB FILEPOOL for this purpose.
Regards
Hans Chr.
On Tue, Sep 27, 2011 at 8:44 PM, Daniel Sparrman
<daniel.sparrman AT exist DOT se> wrote:
> Just to put an end to this discussion, we're kinda running out of limits here:
>
> a) No VTL solution, neither DD, neither Sepaton, neither anyone, is a
> replacement for random diskpools. Doesnt matter if you can configure 50
> drives, 500 drives or 5000 drives, the way TSM works, you're gonna make the
> system go bad since the system is made from having random pools infront,
> sequential pools in the back. A sequential device is not gonna replace that,
> independent being a sequential file pool or a VTL (or, for that question, a
> tape library).
>
> b) VTL's where invented because most backup software (I've only worked with
> TSM, Legato & Veritas aka Symantec) is used to working with sequential
> devices. That havent changed, and wont change in the near future. VTL's (and
> the file device option) is just a replacement. Performance wise, VTL's are
> gonna win all the time compared to a file device, question you need to ask
> yourself is, do I need the VTL, or can I go along with using file devices.
> According to the TSM manual (dont have the link , but if you want i'll find
> it) the maximum supported file device pool for deduplication is 6TB... so if
> you're thinking of replacing a VTL with a seq. file pool, keep that in mind.
> The limit is because the amount of resources needed by TSM to do the file
> deduplication is limited, or as the manual says, "until new technologies are
> available".
>
> The discussion here where people are actually planning on just having a
> sequential pool (since noone is actually discussing that there's a random
> pool infront) is plain scary. No sequential device is gonna have their time
> of the life having a fileserver serving 50K blocks at a time.
>
> So my last 50 cents worth is:
>
> a) Have a random pool infront
>
> b) Depending on the size of your environment, you're either gonna go with a
> filepool and use de-dup (limit is 6TB for each pool, you might not want to
> de-dup everything), or you're gonna go with a fullscale VTL. Choice here is
> size vs costs.
>
> I've seen alot of posts here lately about the disadvantages with VTL's ..
> well, I havent seen one this far with mine. I have a colleague who bought a
> XXXX VTL and found out he needed another VTL just todo the de-dup, since one
> VTL wasnt a supported configuration to do de-dup. I have another colleague
> who bought a very cheap VTL solution (from a very mentioned name around here)
> and ended up with having same hashes, but different data, leaving him with
> unrestorable data.
>
> Comparing eggs to apples just isnt fair. Different manufactures of VTL's do
> different things, meaning both performance and availability is completely
> different.
>
> Just to sum up, we've had both 3584's and (back in the days) 3575, and I've
> never been happier with our VTL (and yes, we do restore tests).
>
> Best Regards
>
> Daniel
>
>
>
> Daniel Sparrman
> Exist i Stockholm AB
> Växel: 08-754 98 00
> Fax: 08-754 97 30
> daniel.sparrman AT exist DOT se
> http://www.existgruppen.se
> Posthusgatan 1 761 30 NORRTÄLJE
>
>
>
> -----"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> skrev: -----
>
>
> Till: ADSM-L AT VM.MARIST DOT EDU
> Från: Rick Adamson <RickAdamson AT WINN-DIXIE DOT COM>
> Sänt av: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
> Datum: 09/27/2011 18:02
> Ärende: Re: [ADSM-L] Ang: Re: [ADSM-L] vtl versus file systems for pirmary
> pool
>
> Interesting. Every VTL based solution, including data domain, that I looked
> at had limits on the amount of drives that could be emulated which were
> nowhere near a hundred let alone a thousand. Perhaps it's time to revisit
> this.
>
> The license is a data domain fee, and a hefty one at that.
>
> The bigger question I have is since the file based storage is native to TSM
> why exactly is using a file based storage not supported?
>
> ~Rick
>
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
> Of Daniel Sparrman
> Sent: Tuesday, September 27, 2011 10:30 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: [ADSM-L] Ang: Re: [ADSM-L] vtl versus file systems for pirmary pool
>
> Not really sure where the general idea that a VTL will limit the number of
> available mount points.
>
> I'm not familiar with Data Domain, but generally speaking, the number of
> virtual tape drives configured within a VTL is usually thousands. Not sure
> why you'd want that many though, I always prefer having a small diskpool
> infront of whatever sequential pool I have, and let the bigger files pass the
> diskpoool and go straightly to the seq. pool.
>
> As far as for LAN-free, the only available option I know of is SANergy. And
> going down that road (concerning both price & complexity) will probably make
> the VTL look cheap.
>
> Not sure what kind of licensing you're talking about concerning VTL, but I
> assume it's a Data Domain license and not a TSM license?
>
> Best Regards
>
> Daniel Sparrman
>
>
>
> Daniel Sparrman
> Exist i Stockholm AB
> Växel: 08-754 98 00
> Fax: 08-754 97 30
> daniel.sparrman AT exist DOT se
> http://www.existgruppen.se
> Posthusgatan 1 761 30 NORRTÄLJE
>
>
>
> -----"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> skrev: -----
>
>
> Till: ADSM-L AT VM.MARIST DOT EDU
> Från: Rick Adamson <RickAdamson AT WINN-DIXIE DOT COM>
> Sänt av: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
> Datum: 09/27/2011 16:52
> Ärende: Re: [ADSM-L] vtl versus file systems for pirmary pool
>
> A couple of things that I did not see mentioned here which I experienced
> was.... for Data Domain the VTL is an additional license and it does
> limit the available mount points (or emulated drives), where a TSM file
> based pool does not. Like Wanda stated earlier depends what you can
> afford !
>
> I myself have grown fond of using the file based approach, easy to
> manage, easy to configure, and never worry about an available tape drive
> (virtual or otherwise). The lan-free issue is something to consider but
> from what I have heard lately is that it can still be accomplished using
> the file based storage. If anyone has any info on it I would appreciate
> it.
>
> ~Rick
> Jax, Fl.
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
> Of
> Tim Brown
> Sent: Monday, September 26, 2011 4:05 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: [ADSM-L] vtl versus file systems for pirmary pool
>
> What advantage does VTL emulation on a disk primary storage pool have
>
> as compared to disk storage pool that is non vtl ?
>
>
>
> It appears to me that a non vtl system would not require the daily
> reclamation process
>
> and also allow for more client backups to occur simultaneously.
>
>
>
> Thanks,
>
>
>
> Tim Brown
> Systems Specialist - Project Leader
> Central Hudson Gas & Electric
> 284 South Ave
> Poughkeepsie, NY 12601
> Email: tbrown AT cenhud DOT com <<mailto:tbrown AT cenhud DOT com>>
> Phone: 845-486-5643
> Fax: 845-486-5921
> Cell: 845-235-4255
>
>
>
>
> This message contains confidential information and is only for the
> intended recipient. If the reader of this message is not the intended
> recipient, or an employee or agent responsible for delivering this
> message to the intended recipient, please notify the sender immediately
> by replying to this note and deleting all copies and attachments.
|
