On 14 okt. 2011, at 04:09, Prather, Wanda wrote:
> Just asking,
> I was told that a Protectier doesn't use SHA1 and can't have a hash collision.
I was told that a protectier uses full (bitwise) matching of chunks, so indeed
can't have hash collisions because there are none.
> Can anybody verify that?
>
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
> Of Remco Post
> Sent: Wednesday, October 05, 2011 3:15 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: [ADSM-L] vtl versus file systems for pirmary pool
>
> Hi,
>
> I saw last week that about half of the people visiting the TSM Symposium were
> running V6, it's been stable for me so far.
>
> The likeliness of an accidental SHA1 hash collision is relatively small even
> compared to the total number of objects that a TSM server could possibly ever
> store during its entire lifetime, insignificant. That being said, if you
> think that your data is to valuable to even risk that, don't dedup.
>
>
> --
>
> Gr., Remco
>
> Op 5 okt. 2011 om 19:24 heeft Shawn Drew <shawn.drew AT AMERICAS.BNPPARIBAS
> DOT COM> het volgende geschreven:
>
>> Along this line, we are still using TSM5.5 Some of the features
>> mentioned previously require TSM6. TSM6 still feels risky to me.
>> Maybe more risky than a hash collision.
>> Just looking for a consensus, Do people think its mature enough now
>> that it is as stable/reliable as TSM5 ?
>>
>> PS. Test restores are the only way to be sure your backups are good.
>> You shouldn't just "trust" TSM.
>>
>> Regards,
>> Shawn
>> ________________________________________________
>> Shawn Drew
>>
>>
>>
>>
>>
>> Internet
>> rrhodes AT FIRSTENERGYCORP DOT COM
>>
>> Sent by: ADSM-L AT VM.MARIST DOT EDU
>> 10/05/2011 11:03 AM
>> Please respond to
>> ADSM-L AT VM.MARIST DOT EDU
>>
>>
>> To
>> ADSM-L
>> cc
>>
>> Subject
>> Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] Ang:
>> Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] Ang: Re: [ADSM-L] vtl
>> versus file systems for pirmary pool
>>
>>
>>
>>
>>
>>
>>> When TSM is duplicating your data (aka backing up storage pools),
>>> there is no logical connection between your primary storage pool and
>>> your copypool.
>>
>> Well . . .yes . .. no . . .
>>
>> All our eggs are in one basket no matter what. The logical connection
>> between pri and copy pools is TSM itself. A logical corruption in TSM
>> can take out both. Your data could be sitting there on tape and
>> completely useless. Yes, that's why we have TSM db backups, but are
>> they good? What if there is a TSM bug that renders all your backups
>> bad - we don't find out until we need it!
>>
>> At some point you have to trust something. We all trust TSM. Yes, we
>> do the db backup, create pri and copy pools, use reuse delay . .
>> .everything to allow for problems . . . but we are still trusting that
>> TSM workss as advertised. A really, really paranoid would run two
>> complete separate/different backup systems - but who can afford that, or
>> want to?
>> But then, we do do that for our biggest SAP/ORacle systems. We use
>> Oracle/RMAN-to-flasharea/RMAN-to-TDPO/TSM, but we also run EMC/clone
>> backups off our DR sites R2's . . but also to TSM.
>>
>>
>> Rick
>>
>>
>>
>>
>>
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--
Met vriendelijke groeten/Kind Regards,
Remco Post
r.post AT plcs DOT nl
+31 6 248 21 622
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