OOOOOOooooh, you're gonna like these drives! They're fast.
The mount and tension up times on our DLT7000's are 2.5 - 3 minutes, on a
good day (not that we have many good days...)
But what really kills you if you're doing a lot of restores is that the
rewind and dismount is ALSO at least 3 minutes.
Unless you get hit with a clean request on dismount, in which case the
cleaning adds another 5-6 minutes, with the robot disabled the entire time.
And we are unable to use collocation on the DLT7000's, they just don't hold
up under the stress. Too many I/O errors (we back up 400 clients with many
many many tiny files....).
With the 9840's, I can start a LABEL LIBV for a range of 10 new tapes, and
get all 10 done in about 10 minutes - mount, ready, write label, rewind,
dismount, checkin, average 60-70 seconds.
I haven't done any careful measurement of time-to-data for the 9840's - I've
been so happy I just didn't care!
From very unscientific sampling of the "waiting for mount of tape xxxx (yy
seconds)" messages on my MOVE DATA processes, I'd guess time-to-data is
going to average around 65-80 seconds. Again, I haven't looked at this
carefully, and not at all for massive restores.
But I'm a happy camper....
************************************************************************
Wanda Prather
The Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu
"Intelligence has much less practical application than you'd think" -
Scott Adams/Dilbert
************************************************************************
> -----Original Message-----
> From: Cris Robinson [SMTP:Cris.Robinson AT LIBERTYMUTUAL DOT COM]
> Sent: Friday, February 18, 2000 8:31 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: ADSM 9840 & Compression
>
> Hi Wanda -
>
> What you found out is very interesting. Looks like you are getting decent
> capacity on the 9840.We would like to improve our restore times by doing
> the
> same conversion from DLT 7000 to 9840 that you now have in progress. I am
> curious what you have seen in your environment as far as tape mount times
> and time to data.
>
> Thanks -
> CR
>
> __________________________________________________
> Cris Robinson
> Sr. Technical Analyst
> Enterprise Storage Management / TSM (ADSM)
> Liberty Mutual Insurance
> Portsmouth, New Hampshire
> 603.431.8400.54837
> mailto:cris.robinson AT libertymutual DOT com
>
> -----Original Message-----
> From: Prather, Wanda [SMTP:Wanda.Prather AT JHUAPL DOT EDU]
> Sent: Monday, February 14, 2000 12:49 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: ADSM 9840 & Compression
>
> We are running 9840's, converting all our old data from DLT7000.
>
> I'm getting exactly the same results on the 9840's that I saw on
> the
> DLT7000's.
>
> If I take a DLT7000 tape that filled at native capacity (35 GB),
> then I know
> it was already-compressed data. A MOVE DATA to a 9840 ends up
> filling the
> 9840 at 20 GB.
>
> If I take a DLT7000 that filled at 70-100GB, I know the data was
> not
> compressed to start with, and a MOVE DATA to a 9840 ends up
> filling
> the 9840
> at 70-80GB.
>
> So it's working about as expected. If the data is compressed by
> the
> software, it isn't going to compress much more in the hardware -
> you'll get
> an additional 10% if you're lucky.
>
> Remember that even if you don't have COMPRESSION ON in the ADSM
> client, some
> types of data are already naturally compressed - Windows machines
> with
> stacking or compression on in the disk file system; Microsoft
> Exchange
> files, SQL data base files, some types of graphics files such as
> .tif and
> .gif files will compress little if at all.
>
> So I find the results on tape vary a whole lot.
>
>
> ************************************************************************
> Wanda Prather
> The Johns Hopkins Applied Physics Lab
> 443-778-8769
> wanda_prather AT jhuapl DOT edu
>
> "Intelligence has much less practical application than you'd
> think"
> -
> Scott Adams/Dilbert
>
> ************************************************************************
>
>
>
>
>
> > -----Original Message-----
> > From: Long, Matt [SMTP:Matt.Long AT MARRIOTT DOT COM]
> > Sent: Monday, February 14, 2000 9:45 AM
> > To: ADSM-L AT VM.MARIST DOT EDU
> > Subject: Re: ADSM 9840 & Compression
> >
> > John,
> >
> > We are also seeing some bizzare compression rates with
> the
> 9840.
> > Some of our tapes are reporting over 80Gig of data. I don't know
> if this
> > is
> > a bug or what. We are using ADSM attached to an AIX RS6000.
> Thanks
> >
> > Matt Long
> > Systems Administration
> > Marriott International
> >
> >
> > -----Original Message-----
> > From: Doherty, John (ANFIS) [mailto:jdohe1 AT ANFIS.CO DOT UK]
> > Sent: Monday, February 14, 2000 5:46 AM
> > To: ADSM-L AT VM.MARIST DOT EDU
> > Subject: ADSM 9840 & Compression
> >
> >
> > ADSM ver 3 rel 1 level 2.20, device class defined as follows
> >
> > <<...>>
> >
> > What level of the ADSM server are you running?
> >
> > Have you specified "9840C" as the format when configuring your
> device
> > class?
> > (Q
> > DEVCLASS)
> >
> >
> > regards,
> >
> > Stuart Robertson
> > Unitech Open Systems Scotland
> >
> >
> > > John Doherty. Tel: +44 (0) 141 275 7793
> > > Fax: +44 (0) 141 275 9199
> > > Email: JDohe1 AT Anfis.co DOT uk
> > >
> > > Technical Specialist, Storage Management L02S
> > >
> > > Email communications are not necessarily secure and may be
> intercepted
> > or
> > > changed after they are sent. Abbey National Financial and
> Investment
> > > Services does not accept liability for any such changes. If
> you
> wish to
> > > confirm the origin or content of this communication, please
> contact the
> > > sender using an alternative means of communication. This
> communication
> > > does not create or modify any contract. If you are not the
> intended
> > > recipient of this communication you should destroy it without
> copying,
> > > disclosing or otherwise using its contents. Please notify the
> sender
> > > immediately of the error.
> > >
> > > ABBEY NATIONAL FINANCIAL AND INVESTMENT SERVICES plc
> > > Registered Office Abbey National House 287 St Vincent
> Street
> > > Glasgow G2 5NB United Kingdom Registered in Scotland
> No
> 159852
> > >
|
