Thread: Slow restoration question
Hello list, what is the quickest way of dumping a DB and restoring it? I have done a "pg_dump -D database | split --line-bytes 1546m part" Restoration as "cat part* | psql database 2> errors 1>/dev/null" all dumpfiles total about 17Gb. It has been running for 50ish hrs and up to about the fourth file (5-6 ish Gb) and this is on a raid 5 server. A while back I did something similar for a table with where I put all the insert statements in one begin/end/commit block, this slowed down the restoration process. Will the same problem [slow restoration] occur if there is no BEGIN and END block? I assume the reason for slow inserts in this instance is that it allows for rollback, if this is the case can I turn this off? Thanks in advance Eric Lam
Eric Lam <elam@lisasoft.com> writes:
> what is the quickest way of dumping a DB and restoring it? I have done a
> "pg_dump -D database | split --line-bytes 1546m part"
Don't use "-D" if you want fast restore ...
regards, tom lane
Tom Lane <tgl@sss.pgh.pa.us> schrieb: > Eric Lam <elam@lisasoft.com> writes: > > what is the quickest way of dumping a DB and restoring it? I have done a > > > "pg_dump -D database | split --line-bytes 1546m part" > > Don't use "-D" if you want fast restore ... hehe, yes ;-) http://people.planetpostgresql.org/devrim/index.php?/archives/44-d-of-pg_dump.html Andreas -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknow) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote: > all dumpfiles total about 17Gb. It has been running for 50ish hrs and up > to about the fourth file (5-6 ish Gb) and this is on a raid 5 server. RAID5 generally doesn't bode too well for performance; that could be part of the issue. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Everyone here always says that RAID 5 isn't good for Postgres. We have an Apple Xserve RAID configured with RAID 5. We chose RAID 5 because Apple said their Xserve RAID was "optimized" for RAID 5. Not sure if we made the right decision though. They give an option for formatting as RAID 0+1. Is that the same as RAID 10 that everyone talks about? Or is it the reverse? Thanks, ____________________________________________________________________ Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com ClickSpace Interactive Inc. Suite L100, 239 - 10th Ave. SE Calgary, AB T2G 0V9 http://www.clickspace.com On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote: > On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote: >> all dumpfiles total about 17Gb. It has been running for 50ish hrs >> and up >> to about the fourth file (5-6 ish Gb) and this is on a raid 5 server. > > RAID5 generally doesn't bode too well for performance; that could be > part of the issue. > -- > Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com > Pervasive Software http://pervasive.com work: 512-231-6117 > vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 > > ---------------------------(end of > broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org >
They are not equivalent. As I understand it, RAID 0+1 performs about the same as RAID 10 when everything is working, but degrades much less nicely in the presence of a single failed drive, and is more likely to suffer catastrophic data loss if multiple drives fail. -- Mark On Tue, 2006-05-02 at 12:40 -0600, Brendan Duddridge wrote: > Everyone here always says that RAID 5 isn't good for Postgres. We > have an Apple Xserve RAID configured with RAID 5. We chose RAID 5 > because Apple said their Xserve RAID was "optimized" for RAID 5. Not > sure if we made the right decision though. They give an option for > formatting as RAID 0+1. Is that the same as RAID 10 that everyone > talks about? Or is it the reverse? > > Thanks, > > ____________________________________________________________________ > Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com > > ClickSpace Interactive Inc. > Suite L100, 239 - 10th Ave. SE > Calgary, AB T2G 0V9 > > http://www.clickspace.com > > On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote: > > > On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote: > >> all dumpfiles total about 17Gb. It has been running for 50ish hrs > >> and up > >> to about the fourth file (5-6 ish Gb) and this is on a raid 5 server. > > > > RAID5 generally doesn't bode too well for performance; that could be > > part of the issue. > > -- > > Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com > > Pervasive Software http://pervasive.com work: 512-231-6117 > > vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 > > > > ---------------------------(end of > > broadcast)--------------------------- > > TIP 4: Have you searched our list archives? > > > > http://archives.postgresql.org > > > > > > ---------------------------(end of broadcast)--------------------------- > TIP 9: In versions below 8.0, the planner will ignore your desire to > choose an index scan if your joining column's datatypes do not > match
RAID 10 is better than RAID 0+1. There is a lot of information on the net about this, but here is the first one that popped up on google for me. http://www.pcguide.com/ref/hdd/perf/raid/levels/multLevel01-c.html The quick summary is that performance is about the same between the two, but RAID 10 gives better fault tolerance and rebuild performance. I have seen docs for RAID cards that have confused these two RAID levels. In addition, some cards claim to support RAID 10, when they actually support RAID 0+1 or even RAID 0+1 with concatenation (lame, some of the Dell PERCs have this). RAID 10 with 6 drives would stripe across 3 mirrored pairs. RAID 0+1 with 6 drives is a mirror of two striped arrays (3 disks each). RAID 0+1 (with concatenation) using 6 drives is a mirror of two volumes (kind of like JBOD) each consisting of 3 drives concatenated together (it's a cheap implementation, and it gives about the same performance as RAID 1 but with increased storage capacity and less fault tolerance). RAID 10 is better than RAID 5 (especially with 6 or less disks) because you don't have the performance hit for parity (which dramatically affects rebuild performance and write performance) and you get better fault tolerance (up to 3 disks can fail in a 6 disk RAID 10 and you can still be online, with RAID 5 you can only lose 1 drive). All of this comes with a higher cost (more drives and higher end cards). -- Will Reese http://blog.rezra.com On May 2, 2006, at 1:49 PM, Mark Lewis wrote: > They are not equivalent. As I understand it, RAID 0+1 performs about > the same as RAID 10 when everything is working, but degrades much less > nicely in the presence of a single failed drive, and is more likely to > suffer catastrophic data loss if multiple drives fail. > > -- Mark > > On Tue, 2006-05-02 at 12:40 -0600, Brendan Duddridge wrote: >> Everyone here always says that RAID 5 isn't good for Postgres. We >> have an Apple Xserve RAID configured with RAID 5. We chose RAID 5 >> because Apple said their Xserve RAID was "optimized" for RAID 5. Not >> sure if we made the right decision though. They give an option for >> formatting as RAID 0+1. Is that the same as RAID 10 that everyone >> talks about? Or is it the reverse? >> >> Thanks, >> >> ____________________________________________________________________ >> Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com >> >> ClickSpace Interactive Inc. >> Suite L100, 239 - 10th Ave. SE >> Calgary, AB T2G 0V9 >> >> http://www.clickspace.com >> >> On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote: >> >>> On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote: >>>> all dumpfiles total about 17Gb. It has been running for 50ish hrs >>>> and up >>>> to about the fourth file (5-6 ish Gb) and this is on a raid 5 >>>> server. >>> >>> RAID5 generally doesn't bode too well for performance; that could be >>> part of the issue. >>> -- >>> Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com >>> Pervasive Software http://pervasive.com work: 512-231-6117 >>> vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 >>> >>> ---------------------------(end of >>> broadcast)--------------------------- >>> TIP 4: Have you searched our list archives? >>> >>> http://archives.postgresql.org >>> >> >> >> >> ---------------------------(end of >> broadcast)--------------------------- >> TIP 9: In versions below 8.0, the planner will ignore your desire to >> choose an index scan if your joining column's datatypes do not >> match > > ---------------------------(end of > broadcast)--------------------------- > TIP 6: explain analyze is your friend
BTW, you should be able to check to see what the controller is actually doing by pulling one of the drives from a running array. If it only hammers 2 drives during the rebuild, it's RAID10. If it hammers all the drives, it's 0+1. As for Xserve raid, it is possible to eliminate most (or maybe even all) of the overhead associated with RAID5, depending on how tricky the controller wants to be. I believe many large storage appliances actually use RAID5 internally, but they perform a bunch of 'magic' behind the scenes to get good performance from it. So, it is possible that the XServe RAID performs quite well on RAID5. If you provided the results from bonnie as well as info about the drives I suspect someone here could tell you if you're getting close to RAID10 performance or not. On Tue, May 02, 2006 at 02:34:16PM -0500, Will Reese wrote: > RAID 10 is better than RAID 0+1. There is a lot of information on > the net about this, but here is the first one that popped up on > google for me. > > http://www.pcguide.com/ref/hdd/perf/raid/levels/multLevel01-c.html > > The quick summary is that performance is about the same between the > two, but RAID 10 gives better fault tolerance and rebuild > performance. I have seen docs for RAID cards that have confused > these two RAID levels. In addition, some cards claim to support RAID > 10, when they actually support RAID 0+1 or even RAID 0+1 with > concatenation (lame, some of the Dell PERCs have this). > > RAID 10 with 6 drives would stripe across 3 mirrored pairs. RAID 0+1 > with 6 drives is a mirror of two striped arrays (3 disks each). RAID > 0+1 (with concatenation) using 6 drives is a mirror of two volumes > (kind of like JBOD) each consisting of 3 drives concatenated together > (it's a cheap implementation, and it gives about the same performance > as RAID 1 but with increased storage capacity and less fault > tolerance). RAID 10 is better than RAID 5 (especially with 6 or less > disks) because you don't have the performance hit for parity (which > dramatically affects rebuild performance and write performance) and > you get better fault tolerance (up to 3 disks can fail in a 6 disk > RAID 10 and you can still be online, with RAID 5 you can only lose 1 > drive). All of this comes with a higher cost (more drives and higher > end cards). > > -- Will Reese http://blog.rezra.com > > > On May 2, 2006, at 1:49 PM, Mark Lewis wrote: > > >They are not equivalent. As I understand it, RAID 0+1 performs about > >the same as RAID 10 when everything is working, but degrades much less > >nicely in the presence of a single failed drive, and is more likely to > >suffer catastrophic data loss if multiple drives fail. > > > >-- Mark > > > >On Tue, 2006-05-02 at 12:40 -0600, Brendan Duddridge wrote: > >>Everyone here always says that RAID 5 isn't good for Postgres. We > >>have an Apple Xserve RAID configured with RAID 5. We chose RAID 5 > >>because Apple said their Xserve RAID was "optimized" for RAID 5. Not > >>sure if we made the right decision though. They give an option for > >>formatting as RAID 0+1. Is that the same as RAID 10 that everyone > >>talks about? Or is it the reverse? > >> > >>Thanks, > >> > >>____________________________________________________________________ > >>Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com > >> > >>ClickSpace Interactive Inc. > >>Suite L100, 239 - 10th Ave. SE > >>Calgary, AB T2G 0V9 > >> > >>http://www.clickspace.com > >> > >>On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote: > >> > >>>On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote: > >>>>all dumpfiles total about 17Gb. It has been running for 50ish hrs > >>>>and up > >>>>to about the fourth file (5-6 ish Gb) and this is on a raid 5 > >>>>server. > >>> > >>>RAID5 generally doesn't bode too well for performance; that could be > >>>part of the issue. > >>>-- > >>>Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com > >>>Pervasive Software http://pervasive.com work: 512-231-6117 > >>>vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 > >>> > >>>---------------------------(end of > >>>broadcast)--------------------------- > >>>TIP 4: Have you searched our list archives? > >>> > >>> http://archives.postgresql.org > >>> > >> > >> > >> > >>---------------------------(end of > >>broadcast)--------------------------- > >>TIP 9: In versions below 8.0, the planner will ignore your desire to > >> choose an index scan if your joining column's datatypes do not > >> match > > > >---------------------------(end of > >broadcast)--------------------------- > >TIP 6: explain analyze is your friend > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Hi Jim,
The output from bonnie on my boot drive is:
File './Bonnie.27964', size: 0
Writing with putc()...done
Rewriting...done
Writing intelligently...done
Reading with getc()...done
Reading intelligently...done
Seeker 2...Seeker 1...Seeker 3...start 'em...done...done...done...
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %
CPU /sec %CPU
0 36325 98.1 66207 22.9 60663 16.2 50553 99.9 710972
100.0 44659.8 191.3
And the output from the RAID drive is:
File './Bonnie.27978', size: 0
Writing with putc()...done
Rewriting...done
Writing intelligently...done
Reading with getc()...done
Reading intelligently...done
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %
CPU /sec %CPU
0 40365 99.4 211625 61.4 212425 57.0 50740 99.9 730515
100.0 45897.9 190.1
Each drive in the RAID 5 is a 400 GB serial ATA drive. I'm not sure
the manufacturer or the model number as it was all in a packaged box
when we received it and I didn't check.
Do these numbers seem decent enough for a Postgres database?
Thanks,
____________________________________________________________________
Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com
ClickSpace Interactive Inc.
Suite L100, 239 - 10th Ave. SE
Calgary, AB T2G 0V9
http://www.clickspace.com
On May 2, 2006, at 3:53 PM, Jim C. Nasby wrote:
> BTW, you should be able to check to see what the controller is
> actually
> doing by pulling one of the drives from a running array. If it only
> hammers 2 drives during the rebuild, it's RAID10. If it hammers all
> the
> drives, it's 0+1.
>
> As for Xserve raid, it is possible to eliminate most (or maybe even
> all)
> of the overhead associated with RAID5, depending on how tricky the
> controller wants to be. I believe many large storage appliances
> actually
> use RAID5 internally, but they perform a bunch of 'magic' behind the
> scenes to get good performance from it. So, it is possible that the
> XServe RAID performs quite well on RAID5. If you provided the results
> from bonnie as well as info about the drives I suspect someone here
> could tell you if you're getting close to RAID10 performance or not.
>
> On Tue, May 02, 2006 at 02:34:16PM -0500, Will Reese wrote:
>> RAID 10 is better than RAID 0+1. There is a lot of information on
>> the net about this, but here is the first one that popped up on
>> google for me.
>>
>> http://www.pcguide.com/ref/hdd/perf/raid/levels/multLevel01-c.html
>>
>> The quick summary is that performance is about the same between the
>> two, but RAID 10 gives better fault tolerance and rebuild
>> performance. I have seen docs for RAID cards that have confused
>> these two RAID levels. In addition, some cards claim to support RAID
>> 10, when they actually support RAID 0+1 or even RAID 0+1 with
>> concatenation (lame, some of the Dell PERCs have this).
>>
>> RAID 10 with 6 drives would stripe across 3 mirrored pairs. RAID 0+1
>> with 6 drives is a mirror of two striped arrays (3 disks each). RAID
>> 0+1 (with concatenation) using 6 drives is a mirror of two volumes
>> (kind of like JBOD) each consisting of 3 drives concatenated together
>> (it's a cheap implementation, and it gives about the same performance
>> as RAID 1 but with increased storage capacity and less fault
>> tolerance). RAID 10 is better than RAID 5 (especially with 6 or less
>> disks) because you don't have the performance hit for parity (which
>> dramatically affects rebuild performance and write performance) and
>> you get better fault tolerance (up to 3 disks can fail in a 6 disk
>> RAID 10 and you can still be online, with RAID 5 you can only lose 1
>> drive). All of this comes with a higher cost (more drives and higher
>> end cards).
>>
>> -- Will Reese http://blog.rezra.com
>>
>>
>> On May 2, 2006, at 1:49 PM, Mark Lewis wrote:
>>
>>> They are not equivalent. As I understand it, RAID 0+1 performs
>>> about
>>> the same as RAID 10 when everything is working, but degrades much
>>> less
>>> nicely in the presence of a single failed drive, and is more
>>> likely to
>>> suffer catastrophic data loss if multiple drives fail.
>>>
>>> -- Mark
>>>
>>> On Tue, 2006-05-02 at 12:40 -0600, Brendan Duddridge wrote:
>>>> Everyone here always says that RAID 5 isn't good for Postgres. We
>>>> have an Apple Xserve RAID configured with RAID 5. We chose RAID 5
>>>> because Apple said their Xserve RAID was "optimized" for RAID 5.
>>>> Not
>>>> sure if we made the right decision though. They give an option for
>>>> formatting as RAID 0+1. Is that the same as RAID 10 that everyone
>>>> talks about? Or is it the reverse?
>>>>
>>>> Thanks,
>>>>
>>>> ___________________________________________________________________
>>>> _
>>>> Brendan Duddridge | CTO | 403-277-5591 x24 |
>>>> brendan@clickspace.com
>>>>
>>>> ClickSpace Interactive Inc.
>>>> Suite L100, 239 - 10th Ave. SE
>>>> Calgary, AB T2G 0V9
>>>>
>>>> http://www.clickspace.com
>>>>
>>>> On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote:
>>>>
>>>>> On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote:
>>>>>> all dumpfiles total about 17Gb. It has been running for 50ish hrs
>>>>>> and up
>>>>>> to about the fourth file (5-6 ish Gb) and this is on a raid 5
>>>>>> server.
>>>>>
>>>>> RAID5 generally doesn't bode too well for performance; that
>>>>> could be
>>>>> part of the issue.
>>>>> --
>>>>> Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
>>>>> Pervasive Software http://pervasive.com work: 512-231-6117
>>>>> vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
>>>>>
>>>>> ---------------------------(end of
>>>>> broadcast)---------------------------
>>>>> TIP 4: Have you searched our list archives?
>>>>>
>>>>> http://archives.postgresql.org
>>>>>
>>>>
>>>>
>>>>
>>>> ---------------------------(end of
>>>> broadcast)---------------------------
>>>> TIP 9: In versions below 8.0, the planner will ignore your
>>>> desire to
>>>> choose an index scan if your joining column's datatypes do
>>>> not
>>>> match
>>>
>>> ---------------------------(end of
>>> broadcast)---------------------------
>>> TIP 6: explain analyze is your friend
>>
>>
>> ---------------------------(end of
>> broadcast)---------------------------
>> TIP 5: don't forget to increase your free space map settings
>>
>
> --
> Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
> Pervasive Software http://pervasive.com work: 512-231-6117
> vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
Tom Lane wrote: >Eric Lam <elam@lisasoft.com> writes: > > >>what is the quickest way of dumping a DB and restoring it? I have done a >> >> > > > >> "pg_dump -D database | split --line-bytes 1546m part" >> >> > >Don't use "-D" if you want fast restore ... > > regards, tom lane > > > thanks, I read that from the doco, the reason why I am using the -D option is because I was informed by previous people in the company that they never got a 100% strike rate in database restoration without using the -D or -d options. If I have enough space on the QA/staging machine I'll give the no options dump restoration a try. Anyone have any estimates the time differences between the -D, -d and [using no option]. regards Eric Lam
On Tue, May 02, 2006 at 08:09:52PM -0600, Brendan Duddridge wrote: > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- >Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec % CPU /sec %CPU > 0 40365 99.4 211625 61.4 212425 57.0 50740 99.9 730515 100.0 45897.9 190.1 [snip] >Do these numbers seem decent enough for a Postgres database? These numbers seem completely bogus, probably because bonnie is using a file size smaller than memory and is reporting caching effects. (730MB/s isn't possible for a single external RAID unit with a pair of 2Gb/s interfaces.) bonnie in general isn't particularly useful on modern large-ram systems, in my experience. Mike Stone
On May 3, 2006, at 8:18 AM, Michael Stone wrote: > On Tue, May 02, 2006 at 08:09:52PM -0600, Brendan Duddridge wrote: >> -------Sequential Output-------- ---Sequential >> Input-- --Random-- >> -Per Char- --Block--- -Rewrite-- -Per Char- -- >> Block--- --Seeks--- >> Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec % >> CPU /sec %CPU >> 0 40365 99.4 211625 61.4 212425 57.0 50740 99.9 >> 730515 100.0 45897.9 190.1 > [snip] >> Do these numbers seem decent enough for a Postgres database? > > These numbers seem completely bogus, probably because bonnie is > using a file size smaller than memory and is reporting caching > effects. (730MB/s isn't possible for a single external RAID unit > with a pair of 2Gb/s interfaces.) bonnie in general isn't > particularly useful on modern large-ram systems, in my experience. > Bonnie++ is able to use very large datasets. It also tries to figure out hte size you want (2x ram) - the original bonnie is limited to 2GB. -- Jeff Trout <jeff@jefftrout.com> http://www.jefftrout.com/ http://www.stuarthamm.net/
On May 3, 2006, at 9:19 AM, Jeff Trout wrote: > Bonnie++ is able to use very large datasets. It also tries to > figure out hte size you want (2x ram) - the original bonnie is > limited to 2GB. but you have to be careful building bonnie++ since it has bad assumptions about which systems can do large files... eg, on FreeBSD it doesn't try large files unless you patch it appropriately (which the freebsd port does for you).
Attachment
On May 3, 2006, at 10:16 AM, Vivek Khera wrote: > > On May 3, 2006, at 9:19 AM, Jeff Trout wrote: > >> Bonnie++ is able to use very large datasets. It also tries to >> figure out hte size you want (2x ram) - the original bonnie is >> limited to 2GB. > > but you have to be careful building bonnie++ since it has bad > assumptions about which systems can do large files... eg, on > FreeBSD it doesn't try large files unless you patch it > appropriately (which the freebsd port does for you). > On platforms it thinks can't use large files it uses multiple sets of 2GB files. (Sort of like our beloved PG) -- Jeff Trout <jeff@jefftrout.com> http://www.jefftrout.com/ http://www.stuarthamm.net/
On Wed, May 03, 2006 at 09:19:52AM -0400, Jeff Trout wrote: >Bonnie++ is able to use very large datasets. It also tries to figure >out hte size you want (2x ram) - the original bonnie is limited to 2GB. Yes, and once you get into large datasets like that the quality of the data is fairly poor because the program can't really eliminate cache effects. IOW, it tries but (in my experience) doesn't succeed very well. Mike Stone
On Wed, 2006-05-03 at 10:59, Michael Stone wrote: > On Wed, May 03, 2006 at 09:19:52AM -0400, Jeff Trout wrote: > >Bonnie++ is able to use very large datasets. It also tries to figure > >out hte size you want (2x ram) - the original bonnie is limited to 2GB. > > Yes, and once you get into large datasets like that the quality of the > data is fairly poor because the program can't really eliminate cache > effects. IOW, it tries but (in my experience) doesn't succeed very well. I have often used the mem=xxx arguments to lilo when needing to limit the amount of memory for testing purposes. Just google for limit memory and your bootloader to find the options.
On Wed, May 03, 2006 at 11:07:15AM -0500, Scott Marlowe wrote: >I have often used the mem=xxx arguments to lilo when needing to limit >the amount of memory for testing purposes. Just google for limit memory >and your bootloader to find the options. Or, just don't worry about it. Even if you get bonnie to reflect real numbers, so what? In general the goal is to optimize application performance, not bonnie performance. A simple set of dd's is enough to give you a rough idea of disk performance, beyond that you really need to see how your disk is performing with your actual workload. Mike Stone
On Wed, May 03, 2006 at 01:06:06PM -0400, Michael Stone wrote: > On Wed, May 03, 2006 at 11:07:15AM -0500, Scott Marlowe wrote: > >I have often used the mem=xxx arguments to lilo when needing to limit > >the amount of memory for testing purposes. Just google for limit memory > >and your bootloader to find the options. > > Or, just don't worry about it. Even if you get bonnie to reflect real > numbers, so what? In general the goal is to optimize application > performance, not bonnie performance. A simple set of dd's is enough to > give you a rough idea of disk performance, beyond that you really need > to see how your disk is performing with your actual workload. Well, in this case the question was about random write access, which dd won't show you. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
On Wed, May 03, 2006 at 01:08:21PM -0500, Jim C. Nasby wrote: >Well, in this case the question was about random write access, which dd >won't show you. That's the kind of thing you need to measure against your workload. Mike Stone
On Wed, 2006-05-03 at 14:26, Michael Stone wrote: > On Wed, May 03, 2006 at 01:08:21PM -0500, Jim C. Nasby wrote: > >Well, in this case the question was about random write access, which dd > >won't show you. > > That's the kind of thing you need to measure against your workload. Of course, the final benchmarking should be your application. But, supposed you're comparing 12 or so RAID controllers for a one week period, and you don't even have the app fully written yet, and because of time constraints, you'll need the server ready before the app is done. You don't need perfection, but you need some idea how the array performs. I maintain that both methodologies have their uses. Note that I'm referring to bonnie++ as was an earlier poster. It certainly seems capable of giving you a good idea of how your hardware will behave under load.
On Wed, May 03, 2006 at 02:40:15PM -0500, Scott Marlowe wrote: >Note that I'm referring to bonnie++ as was an earlier poster. It >certainly seems capable of giving you a good idea of how your hardware >will behave under load. IME it give fairly useless results. YMMV. Definately the numbers posted before seem bogus. If you have some way to make those figures useful in your circumstance, great. Too often I see people taking bonnie numbers at face value and then being surprised that don't relate at all to real-world performance. If your experience differs, fine. Mike Stone
On Wed, 2006-05-03 at 15:53, Michael Stone wrote: > On Wed, May 03, 2006 at 02:40:15PM -0500, Scott Marlowe wrote: > >Note that I'm referring to bonnie++ as was an earlier poster. It > >certainly seems capable of giving you a good idea of how your hardware > >will behave under load. > > IME it give fairly useless results. YMMV. Definately the numbers posted > before seem bogus. If you have some way to make those figures useful in > your circumstance, great. Too often I see people taking bonnie numbers > at face value and then being surprised that don't relate at all to > real-world performance. If your experience differs, fine. I think the real problem is that people use the older bonnie that can only work with smaller datasets on a machine with all the memory enabled. This will, for certain, give meaningless numbers. OTOH, having used bonnie++ on a machine artificially limited to 256 to 512 meg or ram or so, has given me some very useful numbers, especially if you set the data set size to be several gigabytes. Keep in mind, the numbers listed before likely WERE generated on a machine with plenty of memory using the older bonnie, so those numbers should be bogus. If you've not tried bonnie++ on a limited memory machine, you really should. It's a quite useful tool for a simple first pass to figure out which RAID and fs configurations should be tested more thoroughly.
On Wed, May 03, 2006 at 04:30:32PM -0500, Scott Marlowe wrote: >If you've not tried bonnie++ on a limited memory machine, you really >should. Yes, I have. I also patched bonnie to handle large files and other such nifty things before bonnie++ was forked. Mostly I just didn't get much value out of all that, because at the end of theago day optimizing for bonnie just doesn't equate to optimizing for real-world workloads. Again, if it's useful for your workload, great. Mike Stone