[Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread ekke85
Hi I have a Quantum Scalar i500 and it works in Bacula, but it is very slow. It writes at 22mb/sec. The drives should be able to do a lot more then that. I have to backup 11TB that takes a couple of days to complete, I don't want to think how long it would take to restore :( This is the output

[Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread ekke85
Quote: Hi I have a Quantum Scalar i500 and it works in Bacula, but it is very slow. It writes at 22mb/sec. The drives should be able to do a lot more then that. I have to backup 11TB that takes a couple of days to complete, I don't want to think how long it would take to restore Sad This is the

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Thomas Mueller
Am Thu, 05 Aug 2010 05:57:06 -0400 schrieb ekke85: > Hi > > I have a Quantum Scalar i500 and it works in Bacula, but it is very > slow. It writes at 22mb/sec. The drives should be able to do a lot more > then that. I have to backup 11TB that takes a couple of days to > complete, I don't want to t

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Thomas Mueller
> > Hi Thomas > > The spooling attribute was not enabled, I have enabled it now. This is > what I get writing to disk and then also writing that file to tape with > tar: > > > This is a 10gb file to disk: > ]# dd if=/dev/zero of=/home/bigfile bs=1M count=1 1+0 > records in > 1+0 re

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Alan Brown
ekke85 wrote: > The spooling attribute was not enabled, I have enabled it now. This is what I > get writing to disk and then also writing that file to tape with tar: Tape speed testing while writing a repetitive file is useless as hardware compression makes it go a lot faster than natually. Fo

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Cejka Rudolf
ekke85 wrote (2010/08/05): > I do not have spooling on and I don't have software compression on. It seems that you have LTO-3 drive(s). If you are not able to constantly backup data atleast at rate 27 MB/s (HP LTO-3) or 40 MB/s (IBM LTO-3), you need the spooling - which is a must. Note that requir

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Cejka Rudolf
ekke85 wrote (2010/08/05): > slow. It writes at 22mb/sec. The drives should be able to do a lot more > then that. I have to backup 11TB that takes a couple of days to Try tar -cf /dev/null /data-with-11-tb and you will see, if the bottleneck is data source, or something else. How many files do you

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Henry Yen
On Thu, Aug 05, 2010 at 12:46:49PM +0100, Alan Brown wrote: > Tape speed testing while writing a repetitive file is useless as > hardware compression makes it go a lot faster than natually. > > For tape tests use /dev/random On (at least) Linux, /dev/random will quickly block - use /dev/urandom

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread John Drescher
On Thu, Aug 5, 2010 at 8:57 AM, Henry Yen wrote: > On Thu, Aug 05, 2010 at 12:46:49PM +0100, Alan Brown wrote: > >> Tape speed testing while writing a repetitive file is useless as >> hardware compression makes it go a lot faster than natually. >> >> For tape tests use /dev/random > > On (at least

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Henry Yen
On Thu, Aug 05, 2010 at 10:09:06AM -0400, John Drescher wrote: > On Thu, Aug 5, 2010 at 8:57 AM, Henry Yen wrote: > > On (at least) Linux, /dev/random will quickly block - use /dev/urandom > > instead. > > Since these tend to be slow I would just create a large file from one of > these. Well,

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Christian Gaul
Am 05.08.2010 16:57, schrieb Henry Yen: > On Thu, Aug 05, 2010 at 10:09:06AM -0400, John Drescher wrote: > >> On Thu, Aug 5, 2010 at 8:57 AM, Henry Yen wrote: >> > >>> On (at least) Linux, /dev/random will quickly block - use /dev/urandom >>> instead. >>> >> Since these tend to

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-05 Thread Henry Yen
On Thu, Aug 05, 2010 at 17:17:39PM +0200, Christian Gaul wrote: > Am 05.08.2010 16:57, schrieb Henry Yen: First, I welcome this discussion, however arcane (as long as the List permits it, of course) -- I am happy to discover if I'm wrong in my thinking. That said, I'm not (yet) convinced. This p

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-06 Thread Christian Gaul
Am 05.08.2010 21:56, schrieb Henry Yen: > On Thu, Aug 05, 2010 at 17:17:39PM +0200, Christian Gaul wrote: > >> Am 05.08.2010 16:57, schrieb Henry Yen: >> > First, I welcome this discussion, however arcane (as long as the > List permits it, of course) -- I am happy to discover if I'm wrong >

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-06 Thread Paul Mather
On Aug 6, 2010, at 4:48 AM, Christian Gaul wrote: > Am 05.08.2010 21:56, schrieb Henry Yen: >> On Thu, Aug 05, 2010 at 17:17:39PM +0200, Christian Gaul wrote: >> [[...]] >> /dev/urandom seems to measure about 3MB/sec or thereabouts, so creating a large "uncompressible" file could be do

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-08 Thread Henry Yen
On Fri, Aug 06, 2010 at 10:48:10AM +0200, Christian Gaul wrote: > Even when catting to /dev/dsp i use /dev/urandom.. Blocking on > /dev/random happens much too quickly.. and when do you really need that > much randomness. I get about 40 bytes on a small server before blocking. > > Reason 1: the e

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-09 Thread Christian Gaul
Am 09.08.2010 08:55, schrieb Henry Yen: > On Fri, Aug 06, 2010 at 10:48:10AM +0200, Christian Gaul wrote: > >> Even when catting to /dev/dsp i use /dev/urandom.. Blocking on >> /dev/random happens much too quickly.. and when do you really need that >> much randomness. >> > I get about 40 by

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-09 Thread Paul Mather
On Aug 9, 2010, at 2:55 AM, Henry Yen wrote: > On Fri, Aug 06, 2010 at 10:48:10AM +0200, Christian Gaul wrote: >> Even when catting to /dev/dsp i use /dev/urandom.. Blocking on >> /dev/random happens much too quickly.. and when do you really need that >> much randomness. > > I get about 40 bytes

Re: [Bacula-users] Quantum Scalar i500 slow write speed

2010-08-09 Thread Richard Scobie
Paul Mather wrote: > By definition, random data are not compressible. It's my understanding that > the "compressed capacity" of tapes is based explicitly on an expected 2:1 > compression ratio for source data (and this is usually cited somewhere in the > small print). That is a reasonable est