Re: Extremely slow read performance, but write speeds are near-perfect!
On Sep 12, 8:08 am, Bart Van Assche [EMAIL PROTECTED] wrote: Are you aware that not only the readahead settings on the initiator side count, but also on the target side ? I would assume there are, but I don't see options to change that under Windows Storage Server. Wouldn't the write speed be just as bad if this was the cause? - Arnim. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~---
Re: Extremely slow read performance, but write speeds are near-perfect!
When we copy a file from the local disk array to the iSCSI target, the write performance is amazing: we max out the gigabit link immediately (100MB/sec writes easily). When we copy a file from the iSCSI target to the local disk array however, performance is absolutely *dreadful*: Can you try to copy the file from the iSCSI target to /dev/null? This will narrow down whether the problem is with the iSCSI target (or the read mechanism in the iSCSI layer) or with your local disk. Is the 'local disk array' a software RAID ? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~---
Re: Extremely slow read performance, but write speeds are near-perfect!
On Sep 12, 3:49 pm, Konrad Rzeszutek [EMAIL PROTECTED] wrote: Can you try to copy the file from the iSCSI target to /dev/null? Yes, no difference. It's still going at a decidedly unimpressive 1.5MB/ sec. Is the 'local disk array' a software RAID ? No, it's a hardware RAID5 setup over 12 disks, on the HP ProLiant's internal Compaq RAID controller. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~---
Re: Extremely slow read performance, but write speeds are near-perfect!
On Sep 12, 1:29 am, A. Eijkhoudt [EMAIL PROTECTED] wrote: Hello and thanks in advance for reading, We've been having serious read performance issues with Open-iSCSI. I am having a similar problem, with good write performance and dreadful read performance, but with bursts of good speed. I am not entirely sure that this will be the final answer (too many dead ends already), but for me it seems it was a mismatched block size between the target and initiator devices (and upgrading the iSCSI target). The target device had a block size of 4096, while on the initiator side the block size was 512. This issue seemed to manifest itself particularly with multipathing. In my case I am using two Ubuntu boxes (open-iscsi v2.0-865 and IET v0.4.15/0.4.16). I am using software raid (this is a test box) with LVM, and the LV is presented to the iSCSI target. Just my 2c. D.A. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~---
Re: Extremely slow read performance, but write speeds are near-perfect!
More 2c, for everyone. I had unacceptable speeds in general when I first started using open-iscsi, mainly manifested when reading from my IET target (both Ubuntu BTW). One issue was as another user mentioned, I was reading from a fast target (2x3Ghz Xeons) and writing to a slower (1x2.4Ghz P4) more taxed system running software raid. After I realized that the speed issue made more sense as the bottleneck was the writing to the software raid. Anyhow... I enabled jumbo frames on the NICs (MTU 1504), specifically an MTU of 7000 as that is all the client NIC could handle. Although 9000 would've been best. This produced consistent reads from the target at 800Mbps-1Gbps (I was surprised too, used iperf for tests), and write speeds of around 500-650Mbps. Again 2c. Thanks for all the work devs! D.A. wrote: On Sep 12, 1:29 am, A. Eijkhoudt [EMAIL PROTECTED] wrote: Hello and thanks in advance for reading, We've been having serious read performance issues with Open-iSCSI. I am having a similar problem, with good write performance and dreadful read performance, but with bursts of good speed. I am not entirely sure that this will be the final answer (too many dead ends already), but for me it seems it was a mismatched block size between the target and initiator devices (and upgrading the iSCSI target). The target device had a block size of 4096, while on the initiator side the block size was 512. This issue seemed to manifest itself particularly with multipathing. In my case I am using two Ubuntu boxes (open-iscsi v2.0-865 and IET v0.4.15/0.4.16). I am using software raid (this is a test box) with LVM, and the LV is presented to the iSCSI target. Just my 2c. D.A. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~--- smime.p7s Description: S/MIME Cryptographic Signature
