120MB/s uncompressed. With a 2:1 compression ratio you're looking at 240MB/s to a single drive, in real life usually around 100-200MB/s. So if not all of your data is already compressed, encrypted or deduped a single LTO4 drive is limited by a one gigabit transport.
-km On 12 feb 2013, at 20:38, Shawn DREW <[email protected]> wrote: > LTO4 is rated at 120MB/s max speed, which comes out to just under 1gbit/sec > (1gbit/s = 125MB/s). I normally reserve 1gbit for each LTO4 drive. (i.e. 4 > drives on a 4gb HBA) > I do see 110+MB/s streaming on those guys. (using topas -T on AIX, so not > sure about the accuracy) > > > Regards, > Shawn > ________________________________ > Shawn Drew >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] >> Sent: Tuesday, February 12, 2013 12:04 PM >> To: [email protected] >> Subject: Re: [ADSM-L] 1 GBit FC sufficient for tape library? >> >> Another thought: You really want to avoid the LTO4 drives dropping out of >> streaming mode, even if 1Gb/s is enough bandwidth to theoretically move >> the amount of data you need to move. I believe LTO4 will operate down to >> 30-40MB/s. Worth checking, since I'm not sure, but I'm pretty sure you can >> drop as low as 40MB/s and still stay in streaming mode. Once you drop out of >> streaming mode, your throughput will go in the dumper, and you won't get >> anything close to 1Gb/s throughput. >> >> At 10:15 AM 2/12/2013, Michael Roesch wrote: >>> Hi Stefan, >>> >>> one quick question: what are the numbers you are using for your >>> calculation? >>> >>> Did you convert 240 MB/s into Gigabit/s? >>> >>> Thanks >>> >>> Regards, >>> Michael >>> >>> >>> >>> On Tue, Feb 12, 2013 at 1:01 PM, Stefan Folkerts >>> <[email protected]>wrote: >>> >>>> Yes, two LTO4 drives would not be happy at all behind a 1Gb/s HBA, >>>> even two 1Gb/s HBA's are not enough to fully utilize the drives. >>>> I would imagine you could also run into driver/firmware issues with >>>> this combination since it's a very strange one but then again....it >>>> would probably work just slow. >>>> >>>> >>>> On Tue, Feb 12, 2013 at 12:34 PM, Michael Roesch >>>> <[email protected]>wrote: >>>> >>>>> Hi Stefan, >>>>> >>>>> the drives are LTO4 ones. So the HBA would be the bottleneck >>>>> >>>>> >>>>> On Tue, Feb 12, 2013 at 11:36 AM, Stefan Folkerts < >>>>> [email protected] >>>>>> wrote: >>>>> >>>>>> If it is LTO1 or LTO2 you would be OK, if it is LTO3 or higher >>>>>> you are limiting your drivers with your HBA. >>>>>> >>>>>> >>>>>> On Tue, Feb 12, 2013 at 10:39 AM, Michael Roesch >>>>>> <[email protected]>wrote: >>>>>> >>>>>>> Hi all, >>>>>>> >>>>>>> we have an old HP MSL 6030 with two drives that share one 1 >>>>>>> GBit FC >>>>> port. >>>>>>> Would that be enough to use with TSM? I have a feeling that says >> "no" >>>>>> but I >>>>>>> couldn't find any minimum FC requirements. >>>>>>> Anyone having more info? Maybe even an IBM technote? >>>>>>> >>>>>>> Thanks >>>>>>> >>>>>>> Regards, >>>>>>> Michael Roesch >> >> >> -- >> Paul Zarnowski Ph: 607-255-4757 >> CIT Infrastructure / Storage Services Fx: 607-255-8521 >> 719 Rhodes Hall, Ithaca, NY 14853-3801 Em: [email protected] > > > This message and any attachments (the "message") is intended solely for > the addressees and is confidential. If you receive this message in error, > please delete it and immediately notify the sender. Any use not in accord > with its purpose, any dissemination or disclosure, either whole or partial, > is prohibited except formal approval. The internet can not guarantee the > integrity of this message. BNP PARIBAS (and its subsidiaries) shall (will) > not therefore be liable for the message if modified. Please note that certain > functions and services for BNP Paribas may be performed by BNP Paribas RCC, > Inc.
