DS3200 single controller (12x 146GB SAS) connected to x3650 using IBM SAS HBA Controller (LSI 1068E). OS: Win2003 Ent. server x64 SP2, tested also with WinXP x32 SP2 with same results...
I am experiencing very low write performance (about 15 MB/s sequential write on RAID0 array no matter how many hard drives are in, same with 1 or 10). I have already upgraded the HDD firmware, SAS controller firmware and driver to latest releases. The DS3200 has also latest firmware. Is there any setting, that could improve the write performance, that I am missing? Is there anything I could do about it?
Re: DS3200 write performance2008-08-20T20:48:27ZThis is the accepted answer. This is the accepted answer.I am also having write performance issues on a the DS3200 connected to a xSeries 3650, Windows Server 2003 R2 SP2, dual IBM SAS HBA's, dual controllers in the DS3200.
When copying files up to about 4.5 GB the performance is as expected, and the file transfer times are linear for various file sizes up to about 4.5Gb (1.0 Gb = 7 sec, 2.0 Gb = 14 sec, 4.0 Gb = 28 sec). However, if I transfer files larger than about 4.5Gb, the transfer times start to increase exponentially. (I have attached a chart showing this - INT means logical drive internal to the 3650, EXT means logical drive in the DS3200).
When the file transfer starts, Windows estimates a transfer time that is in line with what I would expect for the file size, but at a point about 75% along, the estimated completion time starts to climb dramatically, and then it eventually drops back down to where it should be and the file transfer completes.
I have tried to eliminate the cache in the tests by never transferring the same file twice in a row, and I can recreate the results easily.
IBM will not support 'performance issues', even though I think there is a problem with the firmware, so I'm hoping someone else can either offer some insight into a solution, or confirm my findings so I have some ammunition to drive my point home with their support department.
Re: DS3200 write performance2008-08-21T07:49:52ZThis is the accepted answer. This is the accepted answer.
- SystemAdmin 110000D4XK
I have been working on the topic and in my case, the performance issues were caused mostly by write caching, that was disabled. I had a single controller DS3200, where the write cache is disabled by default, as the cache is not backed up by second controller. After enabling write-cache, the performance went really higher. Therefor I would advise to check if writecache is enabled on all luns you created, even if you write, that you have a dual-controller setup, where the writecaching should be enabled by default. If you intend to transfer mostly large files, you could also consider using higher stripe size (ie 256 or even 512kb). Do your own tests, what will work for you...
Re: DS3200 write performance2008-08-22T20:30:21ZThis is the accepted answer. This is the accepted answer.Write caching is enabled, and disabling it had no effect on the transfer times until I got up to the 7Gb file, and I went from about 4 minutes with write-caching to 11 minutes without it for the file copy. Transfer times for the other smaller file sizes were almost identical to the times with write caching enabled.
I figured this would be the case as the read/write cache is substantially smaller than the files I am testing with, which is by design.
As this storage unit is used primarily for database files and their backups, I will increase the stripe size and re-test.
When watching the file transfer staus indicator, it seems to be around the 5 Gb mark that things slow down. Whether it's a 6, 7, or 10 Gb file, the slowdown always seems to happen about 5 Gb in to the file transfer.
Re: DS3200 write performance2008-08-24T17:52:07ZThis is the accepted answer. This is the accepted answer.Dear ,
You had better check if you mirror cahche is disable. if you are use the single controller and enable the mirror cache . The performance will be became to very lowly, because the sigle controller can't mirror cache. when you enable it,the write cache will be suspension
Re: DS3200 write performance2008-08-25T20:47:02ZThis is the accepted answer. This is the accepted answer.Still hitting a wall on this one. I recreated the array and logical drive using a 512Kb Segment Size and that substantially increased the transfer performance for files up to about 6Gb instead of 5 Gb, but as soon as the transfer hits some point just over 6 Gb, the transfer rate just falls off. Very frustrating.
I even tried formatting a partition on the logical drive with a larger Allocation Unit size, but that proved detrimental.
I'd really like to put this unit into production, but I can't if it's going to underperform on large files. Starting to consider returning the unit to IBM and finding someone else's. IBM won't support me because it's a 'Performance Issue', but this is clearly more than that.
Is there anyone out there with a DS3200 that can recreate the issues I'm having?