Note that increasing iodepth beyond 1 will not affect synchronous ioengines except for small degrees when. Modern midrange storage arrays, like most emc and hp arrays can handle around 2048 outstanding ios. All hosts should have the queue depths set to similar values to give equal. Aug 09, 2016 setting queue depth too low can artificially restrict an applications performance, while setting it too high might cause a slight reduction in io. If it does not allow you to set values higher than 1, maybe your kernel has ncq disabled in general. Is it possible to have a different queue depth set for different luns on the same hba. Therefore, the high watermark must be lower than the whole queue capacity set with queue.
Changing the queue depth for qlogic, emulex, and brocade hbas. Need to change the max queue depth on a qlogic card using qla2xxx module. I have the underlying lun adapter queue depth configured, but id like to configure a max depth of the high level striped lv. This is insufficient for typical configurations that use only a few luns. You can use the qlogic hba management gui or commandline interface cli to modify the qlogic hba queue depth. Small value for slower devices with a high latency like modem links and isdn. For more information, see the documentation on software installation and configuration, and on the commandline interface. In scst, queue depth is per device, does target driver has queue depth per device. Does anyone have any instructions on how to set queue depth on qlogic and emulex fc hbas. The queue depth of the storage adapters varies depending on the brand, chipset used etc. For hpux, the default queue depth is eight ios per lun. A while ago i wrote an article about the queue depth of certain disk controllers and tried to harvest some of the values and posted those up. This can provide significant io improvement and reduce. The maximum value refers to the queue depths reported for various paths to the lun.
Complete the following steps to set the maximum queue depth. But if you must, heres one i used back in the early 2000s that i called chkqdepth. To adjust the maximum queue depth parameter, use the vcli commands. You might need to tune your fc queue depth on the host to achieve the. Trying to write a shell script to check the queue depth on mq server and once its reaches a particular level 5000, mail should be triggered to our mailbox saying for this queue queue depth reached to this value. The linux scsi code automatically adjusts the queue depth as necessary. For suse and red hat the max queue depth parameter for linux is set in nf. The iscsi daemon is configured to have a queue depth different from 128, i. How can i dynamically change the lun queue depth of a disk. The most critical performance will show itself at qd1 queue depth 1 with just 1 worker thread. The virtual scsi queue depth value determines how many requests the disk head driver will queue to the virtual scsi client driver at any one time. There is a bw process, which publish on a queue and there is a consumer on a queue.
To make the updates persistent across reboots, you must then create a new ram disk image and reboot the host. Howto check queue depth of storage adapter or storage device. Pay particular attention to queue depth management for hpux. You can set the length of the transmit queue of the device using sbinifconfig command as follows. Vmware recommends 256, which looks like the middle range. Ssds and linux native command queuing the ongoing struggle. Please run the script and lets fill up the spreadsheet. Why speed up linux software raid rebuilding and resyncing. The storage system has allocated two luns to the server, each connected through four paths in an. Jul 09, 2015 hba queue depth is set to maximum allowed 8192 device lun queue depth is set to maximum allowed 512 storage port have their queue set to maximum 1600 activeactive array. The difference between the high watermark and the overall queue size is a spare memory buffer. Backup the stuff in boot including sub directories, just in case we have to undo something. So if you have a per device per lun queue depth of 32 you can support 128 luns at full queue depth, without queueing in the hba. Dec 15, 2018 why speed up linux software raid rebuilding and resyncing.
Its clear that for a simple fifo queue without prioritization its essential to decrease the queue size and probably also to decrease the mtu if most of the latencysensitive packets are much smaller than the default 1500 bytes, but i dont get the point of decreased buffers with qos. Recently, i build a small nas server running linux for one my client with 5 x 2tb disks in raid 6 configuration for all in one backup server for linux, mac os x, and windows xpvista710 client computers. Perform the following steps to set the maximum queue depth. If you increase the queue depth to 64 as is the new default in. The default is 32, and the valid range is 1 to 255. If no indications of resource problems occur within this period, linux increases the queue. Esxi offers the ability to configure queue depth limits for devices on an hba or iscsi initiator. To remedy this, you can add a twoport fc target adapter to each controller, then rezone your fc switches so that 15 of your 30 hosts connect to one set of ports, and the remaining 15 hosts connect to a second set of ports. With set lun queue depth to maximum its depended to your hba, you should read hba vendor document 100 x 512 maximum lun queue depth51,200. Make the desire queue depth changes described in step 1.
For aix client logical partitions, you can change this value from the default value of 3 to a value from 1 256 by using the chdev command. In the eva 468000 best practice docs i find this quote. The maximum scsi queue depth value, as determined by the microsoft port driver developer, is 254. Setting queue depth too low can artificially restrict an applications performance, while setting it too high might cause a slight reduction in io. The storage adapters with queue depth 25 are the bottom line which shows their limit when rebuild kicks in and good storage adapters ones with queue depth 600 or 1200. How do i set multiple different lun queue depths for. A queue exist on the storage array controller port as well, this is called the target port queue depth. Jun 19, 20 altering the software iscsi adapter queue depth to 64 decreases latency between storage device and software iscsi initiator by an average of 0. Updating emulex hba queue depths on a linux host netapp. Im experimenting with the effects of different scsi queue depth values on a dell server running centos linux 5. Queue depth is something that is normally changed at the hba driver level. Either i would like to write a java program which monitors a queue depth and based on the out come, the publisher should decide whether to publish a message or waitsleep for few secmin. The server can have 32 lun maximum and the server can generate.
If this value is reported, red hat recommends that applications issue io aligned to and. Setting the queue depth for a scsi device on linux on ibm. Write a udev rule to change the setting for each new scsi device. Jun 08, 2011 trying to write a shell script to check the queue depth on mq server and once its reaches a particular level 5000, mail should be triggered to our mailbox saying for this queue queue depth reached to this value. Linux forwards scsi commands to the storage server until the number of pending commands exceeds the queue depth. The queue depth for all devices on the qlogic hba is a total of 4096.
Queues, queues and more queues virtualize applications. The device being used may support greater queue depth, but increasing the. The maximum queue depth setting can significantly influence the storage. If the queue depth limit is set too low, iops and throughput can be limited and latency can increase due to queuing. Working with queues in rsyslog red hat enterprise linux. Even async engines may impose os restrictions causing the desired depth not to be achieved. You can update the device queue depth of a qlogic driver on a linux host. Schednumreqoutstanding value, see setting the maximum outstanding disk requests for virtual machines 1268 for more information about setting queue depth for an emulex host bus adapter hba on esx 3.
To set the size of a class queue that is, to configure the maximum number of packets that a class queue can hold, complete the following steps. Setting the depth of a traffic class queue controls when the router drops packets for example, using tail drop. Because the servers hbas can generate high workload so you need to have estimated from storage point of view. Mar 04, 2009 the execution throttle\ queue depth can be set to 6,5 t2048 1 q 15 6,5 but using this setting one esx host can fill the entire target port queue depth by itself, but the environment exists of 8 esx hosts.
If step 1 does not make the new queue depth settings stick, then we have to do a little more. Will that be creating parallel jobs, but then again there is an option to run jobs in parallel also will that not be a trivial or conflicting. I have the underlying lun adapter queue depth configured, but id like to. Tuning the performance of intel optane ssds on linux. The maximum depth of the queue in sata is 31 for practical purposes, and so if the drive supports ncq then linux will usually set the depth to 31. Setting the queue depth for a scsi device on linux on ibm z. A physical server perspective assuming average 10 ms latency between the host and storage array. Number of io units to keep in flight against the file. This test tests whether the queue depth of the iscsi daemon on linux is equal to 128. Update the queue depths by adding the queue depth parameter to the etcnf file for a red hat enterprise linux 5.
If you want to make the modifications persistent, perform the following steps. The disk queue depth limits the maximum number of commands that the linux software can issue concurrently to that disk at any time. Configure your host running the linux operating system. The queue depth setting specifies the number of outstanding requests per lun. This dictates how many ios can be outstanding to a given device before ios start queuing in the esxi kernel. This guide was created as an overview of the linux operating system, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter. Vmware esxi queue depth overview, configuration and. For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. Im trying to figure out how to go about changing queue depth setting on my hbas. Mpio is also useful when connecting multiple sessions to iscsi volumes if you need a queue depth greater than the single iscsi connection queue depth of 32. Hba queue depth is set to maximum allowed 8192 device lunqueuedepth is set to maximum allowed 512 storage port have their queue set to maximum 1600 activeactive array. Suse linux enterprise server how to increase the max queue. Linux increasing the transmit queue length txqueuelen.
How do i set multiple different lun queue depths for different luns on. The queue depth in the operating systems must be set to four concurrent commands per path. To set the default io scheduler, you can use the tuned tool, or modify the. Specifically trying to limit the queue depth as measured through iostat. What is hba queue depth and how to check the current queue.
In addition, i would like to set different queue depth value per ports. Jun 10, 2008 setting the depth of a traffic class queue. H ow do i set txqueuelen the length of the transmit queue length of the network card device under linux. I would like to connect with different multiple disk storage from dl380 via fibre chanel using hpe 2port 16gb host bus adapter. When you lower this value, it throttles the hosts throughput and alleviates san contention concerns if multiple hosts are overutilizing the storage and are filling its command queue. Log in to your red hat account red hat customer portal. The desired queue depth of 3,840 exceeds the available queue depth per port.
Changing the queue depth is usually a storage server requirement. Check the documentation of the storage server used or contact your storage server support group to establish if there is a need to change this setting. Adjust queue depth for qlogic, emulex, and brocade hbas. Linux iscsi configuration should set queue depth to 128. Configure your host that is running the linux operating system. Note which ramfs image grub is using, see the initrd line in bootgrubnf.
The server has two qlogic qle2560 fc hbas connected via multipathing to a storage system. Number of io which can be generated per lun with single queue depth slot ms average latency between host and storage array if latency is 10ms, server can generate 100 iops. Then, how is it possible to control queue depth with an iodepth parameter from fio command. If the server lacks the resources to process a scsi command, linux queues the command for a later retry and decreases the queue depth counter. Increasing the disk queue depth might improve the disk performance by increasing disk throughput or io but might also increase latency response delay. Configuration tools red hat enterprise linux 7 red hat. Hi, guys, i have a dl380 runing redhat enterprise linux 7. Reboot the host and confirm that the queue depth values are set correctly. Altering the software iscsi adapter queue depth to 192 increases latency between storage device and software iscsi initiator by an average of 6. Changing the queue depth for qlogic, emulex, and brocade. Jan 17, 2020 the most critical performance will show itself at qd1 queue depth 1 with just 1 worker thread. Oct 22, 2009 you can set the length of the transmit queue of the device using sbinifconfig command as follows. Is iodepth of fio and queue depth of storage both same.
Setting queue depth correctly allows the controllers on the hitachi storage system to optimize multiple ios to the physical disk. Mpio software is required for connections to solidfire series fc volumes because it offers a way to consolidate the multiple paths available to an fc volume into a single usable device. Altering the software iscsi adapter queue depth to 64 decreases latency between storage device and software iscsi initiator by an average of 0. You can change the queue depth of emulex hbas and qlogic hbas on linux hosts. However, fortunately the shallow queue depth of sata can easily be overcome by using nlsas drives nearline serially attached scsi instead. Setting queue depths on linux hosts netapp documentation.
484 177 1304 1043 321 1042 1128 1367 1339 710 1342 1442 1183 1101 501 81 198 1055 439 1022 25 1081 243 1359 1020 911 898 1328 1195 670 383 1251 933 1254 1276 567 1119 1290 1073 372