Re: [Bacula-users] LTO3 tape capacity lower than expected
2010-01-07 01:37:32
>> > With
>> >
>> > Maximum File Size = 5G
>> > Maximum Block Size = 262144
>> > Maximum Network Buffer Size = 262144
>> >
>> > I get up to 150M MB/s while despooling to LTO-4 drives. Maximum File
>> > Size gave me some extra MB/s, I think it's as important as the
>> > Maximum Block Size.
>> >
>> >
>> thanks for providing this hints. just searching why my lto-4 is writing
>> just at 40mb/s. will try them out!
>>
>> searching the "Maximum File Size" in the manual I found this:
>>
>> If you are configuring an LTO-3 or LTO-4 tape, you probably will want
>> to set the Maximum File Size to 2GB to avoid making the drive stop to
>> write an EOF mark.
>>
>> maybe this is the reason for the "extra mb/s".
>
> Modifying the Maximum Block Size to more than 262144 didn't change much
> here. But changing the File Size did. Much.
I found a post from Kern saying that Quantum told him, that about 262144
is the best blocksize - increasing it would increase error rate too.
>
> Anyway, 40 MB/s seems a bit low, even with the defaults. Before tuning
> our setup I got ~75 MB/s. Are you spooling the data to disk or writing
> directly to tape?
yes, i was surprised too that it is that slow.
I'm spooling to disk first (2x 1TB disk as RAID0, dedicated to bacula for
spooling). i will also start a sequential read test to check if the disks
are the bottleneck. The slow job was the only one running.
watching iotop i saw the "maximum file size" problem: it stops writing
after 1 GB (default file size) and writes to the DB and then continues
writing. so for a LTO-4 it stops nearly 800 times until the tape is full.
- Thomas
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- Re: [Bacula-users] LTO3 tape capacity lower than expected, (continued)
- Re: [Bacula-users] LTO3 tape capacity lower than expected, John Drescher
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Tino Schwarze
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Ralf Gross
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Thomas Mueller
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Ralf Gross
- Re: [Bacula-users] LTO3 tape capacity lower than expected,
Thomas Mueller <=
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Ralf Gross
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Jesper Krogh
- Re: [Bacula-users] LTO3 tape capacity lower than expected, Brian Debelius
- [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Steve Costaras
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Dan Langille
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Steve Costaras
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Martin Simmons
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Steve Costaras
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Dan Langille
- Re: [Bacula-users] bacula 3.0.3 maintain ctime on restored files?, Steve Costaras
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